| 1. |
飯盛拓嗣, 今村均, 宮町俊生, 中辻寛, 北村未歩, 堀場弘司, 間瀬一彦, Anton Visikovskiy, 田中悟, 小森文夫, 1度以下のツイスト2層グラフェンの電子状態, 日本物理学会 2023年春季大会, 2023.03. |
| 2. |
今村 均、田中 夏帆、飯盛 拓嗣、中辻 寛、宮町 俊生、小森 文夫、ビシコフスキー アントン、田中 悟, 4H-SiC m面上のグラフェン周期リップル構造, 第83回 応用物理学会 秋季学術講演会, 2022.09. |
| 3. |
田中 悟, Twisted bilayer graphene with clean interface by direct transfer of CVD graphene, 第59回 フラーレン・ナノチューブ・グラフェン 総合シンポジウム, 2020.09. |
| 4. |
田中悟, 大面積ツイスト2層グラフェンの作製と電子状態評価, 日本物理学会 2020年秋季大会, 2020.09. |
| 5. |
S. Tanaka, H. Imamura, R. Uotani, T. Kajiwara, A. Visikovskiy, T. Iimori, T. Miyamachi, K. Nakatsuji, K. Mase, F. Komori, Fabrication and characterization of twisted bilayer graphene, Materials Research Meeting 2019 December 10-14, 2019, Yokohama, Japan, 2019.12, Twisted bilayer graphene (TBG) exhibits unique electronic characteristics depending on its in-plane rotation-angle due to moiré potential. The Fermi velocity decreases dramatically with the angle less than 5° and moreover, superconductivity is emerged at approximately 1° magic angle. TBG has been fabricated by tape-exfoliation of CVD graphene on metal substrates and transferring processes. However, these processes have potential problems in obtaining large area, precise control of the rotation angle, and contamination. A large area sample is especially desired to evaluate electronic structure by angle-resolved photoemission spectroscopy (ARPES), which normally measures macroscopic area. Therefore, we aimed at solving these problems by direct transfer of newly developed CVD grown graphene on SiC.. |
| 6. |
S. Tanaka, H. Imamura, R. Uotani, T. Kajiwara, A. Visikovskiy, T. Iimori, T. Miyamachi, K. Nakatsuji, K. Mase, F. Komori, Rotation-angle controlled twisted bilayer graphene, 12th International Symposium on Atomic Level Characterizations for New Materials and Devices '19, 2019.10, Twisted bilayer graphene (TBG) shows variety of electronic characteristics depending on its in-plane rotation-angle due to moiré potential. The Fermi velocity decreases dramatically with the angle less than 5° and moreover, superconductivity is emerged at approximately 1° magic angle. TBG has been fabricated by tape-exfoliation and transferring processes. However, these processes have potential difficulties in obtaining large area, precise control of the rotation angle, and contaminant-free interlayer structures. A large area sample is especially essential to evaluate electronic structure by macro-probe characterizations such as angle-resolved photoemission spectroscopy (ARPES). Thus, we aimed at solving these problems by direct transfer of newly developed CVD grown graphene on SiC in vacuum.. |
| 7. |
Ryosuke Uotani, Hitoshi Imamura, Takashi Kajiwara, Anton Visikovskiy, Takushi Iimori, Fumio Komori, Satoru Tanaka, Periodically rippled graphene formed on 4H–SiC m-plane surface, International Symposium on Epitaxial Graphene 2019 (ISEG2019), 2019.08. |
| 8. |
Kohei Fukuma, Anton Visikovskiy, Takashi Kajiwara, Takushi Iimori, Fumio Komori, Satoru Tanaka, Graphene nanoribbons on macro-facets of vicinal 6H-SiC(0001) , International Symposium on Epitaxial Graphene 2019 (ISEG2019), 2019.08. |
| 9. |
Hitoshi Imamura, Ryosuke Uotani,Takashi Kajiwara, Anton Visikovskiy, Takushi Iimori, Kan Nakatsuji, Kazuhiko Mase, Fumio Komori, Satoru Tanaka, Moiré induced electronic structure of twisted bilayer graphene, International Symposium on Epitaxial Graphene 2019 (ISEG2019), 2019.08. |
| 10. |
田中 悟, IV族三角格子原子層の成長と電子物性, 第２回陽電子回折研究会, 2018.02. |
| 11. |
Kohei Fukuma, Anton Visikovskiy, Shingo Hayashi, Takashi Kajiwara,Takushi Iimori,Fumio Komori, Satoru Tanaka, Graphene nanoribbons grown on facets resulted from macro-step bunching on vicinal SiC surfaces, International Symposium on Epitaxial Graphene 2017 (ISEG2017), 2017.11, Graphene is expected to be used for the next generation ultra-fast switching devices. For this purpose the bandgap opening is the central issue and thus graphene nanoribbons1 (GNRs) have been investigated by many researchers. We reported GNR growth on periodic nanofacet SiC surfaces by molecular beam epitaxy (MBE) and showed the bandgap opening at K-point by angle-resolved photoemission spectroscopy (ARPES)2. We also found the periodically rippled graphene on the facets on vicinal SiC substrates via surface decomposition. As is illustrated in Fig. 1 GNR-like layer is possibly present at the interface3. To investigate the “real” feature of the interface layer by STM/STS, Raman spectroscopy, and LEED we tried to remove the top rippled graphene.. |
| 12. |
Anton Visikovskiy,Shingo Hayashi,Fumio Komori, Satoru Tanaka, Sn and Pb triangular lattice atomic layers on SiC(0001) and at graphene/SiC(0001) interface
, International Symposium on Epitaxial Graphene 2017 (ISEG2017), 2017.11, The research of 2D Dirac materials has been one of the main topics in recent material science, because of wide possible device application and fascinating physics. Most studies, however, are concentrated on graphene-like honeycomb lattice materials (graphene, silicene, germanene, stanene, etc.)1,2, though other lattice types may possess similar electronic structure features. Dense triangular lattice atomic layers (TLAL) of heavy group IV elements (Sn, Pb) on SiC(0001) surface and at graphene/SiC(0001) interface could be such materials (Fig. 1a,b). Additionally, heavy group IV elements exhibit strong spin-orbit coupling (SOC) which may significantly contribute to electronic structure of 2D layers and result in spin-polarized states. Previous studies did consider sparse triangular systems of group IV adatoms on SiC surface in terms of frustrating magnetic order, spin liquids, and Mott-type insulator state3. However, dense atomic layers where Sn (or Pb) atoms directly interconnected by in-plane bonds are unexplored.. |
| 13. |
Shingo Hayashi, Takashi Kajiwara, Anton Visikovskiy, Takushi Iimori, Tetsuro Shirasawa, Kan Nakastuji, Toshio Miyamachi, Syuhei Nakashima,
Kazuhiko Mase, Fumio Komori, Satoru Tanaka, Sn atomic layer by intercalation at graphene / SiC interface, International Symposium on Epitaxial Graphene 2017 (ISEG2017), 2017.11, Researches on atomic layer materials of group IV elements attracts great attention. Among them,
stanene, an atomic layer of Sn, is expected to exhibit such unique characteristics as a two dimensional topological insulator [1] and quantum anomalous Hall effect [2]. The growth of stanene on Bi2Te3 has been achieved [3] but no experimental evidence on such characteristics is yet reported. On the other hand, since Sn shows a large spin orbit coupling (SOC), the spin and electronic states in terms of Rashba splitting, antiferromagnetic order and Mott insulator transition etc. are investigated. Adatom Sn (√3×√3) R30° (R3) structure on semiconductor substrates (Ge, SiC) has been reported [4, 5]. Thus, we have been aiming at forming stanene on SiC(0001) surfaces. Here, we tried Sn intercalation at graphene/SiC interfaces, which are advantageous to any ex-situ measurements of a Sn interlayer.. |
| 14. |
Takashi Kajiwara, Anton Visikovskiy,Takushi Iimori,Toshio Miyamachi,Fumio Komori,Satoru Tanaka, Graphene transfer on periodic SiC nanosurfaces, International Symposium on Epitaxial Graphene 2017 (ISEG2017), 2017.11, Graphene growth by thermal decomposition of SiC(0001) surface is more advantageous than other methods because of epitaxial nature on wafer scale. However, the electrical properties are somehow limited by the presence of surface steps and excess bilayer, which causes the carrier scattering and thus degrade the mobility. To solve the problems exfoliation and transferring of epitaxial graphene grown SiC has recently been paid attention. However, the transfer of monolayer graphene directly from a SiC surface is difficult because its relatively strong interaction with a buffer layer ((6√3 ́6√3)R30° structure (6R3)). J. Kim et al. reported a layer resolved graphene transfer technique from SiC surface using Ni stressor layer1. They demonstrated that the electronic properties of graphene are remarkably improved by deleting the bilayer region and transferring it to a flat surface2. In addition, transferring monolayer graphene with defined crystal orientation to various substrates enables to realize controllable moiré superstructures, which shows fractal quantum Hall effects3.. |
| 15. |
林 真吾，田中 悟, SiC(0001)上のIV族原子層膜の形成, 陽電子回折研究会, 2017.01, Graphene を始めとした原子層物質の研究において,同じ IV 族元素である Sn の原子層 (stanene)の形成が試みられている[1].Stanene は 2 次元トポロジカル絶縁性[2]やスピン量 子ホール効果(SQHE)などの物性が期待されている.そこで我々は SiC 上への stanene 形成を 目的として,SiC 上の Sn の吸着—成長に関する研究を行っている.SiC は 6√3 バッファー層 を介してグラフェンのエピタキシャル成長が生じる.また,化学的安定性やワイドギャップ 半導体であることから,2次元物質の成長及び物性測定に適した基板材料である.また,SiC 上の Sn はモット絶縁体の状態を調べる研究対象にもなっており,吸着 Sn 同士の大きな相互 作用に関しても注目されている[3].
本研究では SiC(0001)-adatom Si に現れる様々な表面構造に着目し,Sn 吸着状態や成長モ ードへの影響を調べた.過去の研究において Si(111)7×7 表面の Sn は,再表層の Si ダング リングボンドを終端し,Si との混成がないことが報告されている[4].今回,Si-(√3×√3), (2√3×2√13)構造上及びグラフェン/SiC 界面への Sn 成長を行い,形成された構造を XPS・ ARPES・LEED 等を用いた解析を行った.. |
| 16. |
田中 悟，小森 文夫，神田 晶申, SiCナノ表面構造制御によるグラフェンナノ構造化, 東北大通研「炭化珪素系ヘテロ構造を用いた物質創成と応用展開」 第２回研究会, 2017.01. |
| 17. |
T. Takasaki, J. Shioji, T. Kajiwara, A. Visikovskiy, S. Tanaka, Anisotropic growth of graphene on cleaved SiC(1-100) surfaces, 18th International Conference of Crystal Growth and Epitaxy (ICCGE18), 2016.08, Graphene nanoribbons (GNRs) are of importance for switching device applications because of possible bandgap opening at K-points. Many approaches have been proposed to tailor narrow ribbons, however, so far no effective or practical method is achieved.
SiC is known to be a good template for graphene epitaxial growth via surface decomposition. There have been many researches on polar SiC(0001) surfaces, on which an uniform thick graphene layer is grown. This structure is beneficial to investigate Dirac physics in terms of crystal quality. In order to modify electronic structure at K-points of graphene on such SiC substrates, e.g. bandgap creation, it is necessary to consider alternating growth ideas. We here demonstrate graphene growth on nonpolar SiC(1-100) surfaces [1, 2] showing lower crystal symmetry, that may induce anisotropic graphene growth, and thus GNR formation.. |
| 18. |
A. Visikovskiy, S.-I. Kimoto, T. Kajiwara, M. Yoshimura, F. Komori, S. Tanaka, Graphene/SiC(0001) interface variety induced by Si intercalation, 18th International Conference of Crystal Growth and Epitaxy (ICCGE18), 2016.08, Graphene is an important 2D material with extremely useful properties for device applications. Growth of graphene on substrates faces the problem of interface influence on graphene's properties. In particular, graphene forms buffer layer when growing on SiC(0001) which does not possess characteristic graphene band dispersion and affect, often negatively, subsequent graphene layers. The interface between graphene and SiC can be modified by different atoms intercalation. In the present work, we consider one of the simplest case of Si intercalation. Various amounts of Si atoms were intercalated into graphene/SiC(0001) interface and studied by means of electron diffraction (LEED, RHEED), scanning tunneling microscopy (STM), angle-resolved photoemission (ARPES) and computational methods. We have shown that interface structures are similar to those formed by Si adsorption on clean SiC(0001) surface. The formation of these interface structures decouples graphene layer from substrate and restore it's linear electronic band dispersion.. |
| 19. |
Tanaka Satoru, Takashi Kajiwara, ANTON VISIKOVSKIY, Graphene lateral superlattices formed on SiC facets - semiconducting and ballistic transport -
, 2015 MRS Fall Meeting , 2015.11. |
| 20. |
Tanaka Satoru, Takashi Kajiwara, ANTON VISIKOVSKIY, Sub 2‐dimensional graphene nanostructures formed on SiC(1‐108) facets ‐ semiconducting and ballistic transport, 16th International Conference on Silicon Carbide and Related Materials(ICSCRM2015), 2015.10. |
| 21. |
Tanaka Satoru, Quasi-one-dimensional graphene nanostructure on corrugated SiC surfaces, 21st International Conference on Electronic Properties of Two-Dimensional Systems 17th International Conference on Modulated Semiconductor Structures, 2015.07. |
| 22. |
田中 悟, Formation of graphene lateral superlattices on self-ordered SiC facets, 第34回電子材料シンポジウム(30th Electronic Materials Symposium), 2015.07. |
| 23. |
Tanaka Satoru, Semiconducting characteristics in self-ordered quasi-one dimensional graphene lateral superlattice, NT-15, 2015.06. |
| 24. |
田中 悟, SiC ウエハ上のグラフェンナノ構造とデバイス応用, 第7回 ワイドバンドギャップ半導体デバイスに関わる超精密加工プロセス研究分科会 講演会 第28回 精密加工プロセス研究会 講演会, 2015.06. |
| 25. |
S. Tanaka, ナノ表面構造制御によるヘテロエピタキシー, 第55回真空に関する連合講演会, 2014.11. |
| 26. |
Tanaka Satoru, One-dimensional Si adatom induced nanoribbon formation on SiC surface during molecular beam epitaxy, IUMRS-IECM 2012, 2014.08. |
| 27. |
S. Tanaka, MBE法による傾斜SiC表面上へのグラフェンナノリボンの成長, 第33回電子材料シンポジウム(30th Electronic Materials Symposium), 2014.07. |
| 28. |
田中 悟, SiC表面ナノ構造上のグラフェンナノリボンの形成と電子物性, 日本物理学会第６6回年次大会領域9，領域7合同シンポジウム 主題：表面界面状態の理解と触媒反応・電子デバイスへの新展開, 2014.03. |
| 29. |
Shingo Hayashi, Takashi Kajiwara, ANTON VISIKOVSKIY, Tanaka Satoru, Intermediate C-Rich (Sqrt [3] x Sqrt [3]) R30 Structure Preceding Graphene Buffer Layer Formation on SiC (0001), ICSCRM2013, 2013.10. |
| 30. |
Tanaka Satoru, Takashi Kajiwara, ANTON VISIKOVSKIY, Bandgap Opening on Graphene Nanoribbons Grown on Vicinal 6H- and 4H-SiC Surfaces by Molecular Beam Epitaxy, ICSCRM2013, 2013.09. |
| 31. |
Shin-ichi Kimoto, Takashi Kajiwara, ANTON VISIKOVSKIY, Tanaka Satoru, Silicon Intercalation at the SiC-Graphene Interface, ICSCRM2013, 2013.09. |
| 32. |
Tanaka Satoru, Growth of graphene nanoribbon arrays on vicinal SiC surfaces by molecular beam epitaxy, Physical Sciences Symposia-2013, 2013.09. |
| 33. |
Tanaka Satoru, グラフェンナノ構造形成と物性相関, 日本学術振興会第167委員会, 2013.04. |
| 34. |
Takashi Kajiwara, Tanaka Satoru, Epitaxial Graphene Nanoribbons Grown by Molecular Beam Epitaxy, 2012 MRS Fall Meeting, 2012.11. |
| 35. |
中森 弓弦, Tanaka Satoru, Raman Spectroscopy of Epitaxial Graphene Nanoribbons, 2012 MRS Fall Meeting, 2012.11. |
| 36. |
Yoshihito Hagihara, Tanaka Satoru, Graphene Growth on SiC Nanofacet Surfaces by Chemical Vapor Deposition, 2012 MRS Fall Meeting, 2012.11. |
| 37. |
Tanaka Satoru, Graphene nanoribbons grown by molecular beam epitaxy, IUMRS-IECM 2012, 2012.09. |
| 38. |
Takashi Kajiwara, Yusuke Kurisu, and Satoru Tanaka
, Graphene nanostructures on vicinal SiC surfaces
, Materials Research Society Fall Meeting 2011, 2011.11. |
| 39. |
田中 悟, グラフェンナノ構造の形成と構造ー電子物性相関, 早稲田大学各務記念材料技術研究所オープンセミナー, 2011.10. |
| 40. |
S. Tanaka, Graphene nanoribbons on vicinal SiC surfaces, 2011.10. |
| 41. |
S. Tanaka, Formation of graphene nanostructures on vicinal SiC surfaces, 2011 International Conference on Solid State Devices and Materials, 2011.09. |
| 42. |
S. Tanaka, Formation of epitaxial grapehene nanostructures and correlation with electronic structures, 第30回電子材料シンポジウム(30th Electronic Materials Symposium), 2011.07. |
| 43. |
田中 悟, SiCナノ表面構造とヘテロエピタキシー, 真空・表面科学合同講演会, 2010.11. |
| 44. |
S. Tanaka, K. Morita, N. Uehara, K. Nakatsuji, T. Yoshimura, F. Komori, Self-organized graphene nanoribbons on vicinal SiC surfaces, International Symposium on Graphene Dvices (ISGD) 2010, 2010.10. |
| 45. |
Satoru Tanaka, Kouhei Morita, Naoya Uehara, Hiroki Hibino, Growth mechanisms of graphene on vicinal SiC surfaces, European Materials Society (E-MRS) Spring Meeting, 2010.06. |
| 46. |
田中 悟, SiCナノ表面上へのエピタキシャルグラフェンの形成と評価, 日本物理学会第６５回年次大会領域7，領域4，領域6，領域9合同シンポジウム 主題：グラフェンの生成・評価と物性 －最前線と展望－, 2010.03. |
| 47. |
Srey Chenda, Satoru Tanaka , Formation of graphene nanowires on vicinal SiC surfaces, MRS 2009 Fall Meeting, 2009.12. |
| 48. |
Akihiro Hashimoto, Hiromitsu Tearsaki, Kouhei Morita, Satoru Tanaka and Hiroki Hibino, A breakthrough toward wafer-size bilayer graphene transfer, 2009 MRS Fall Meeting, 2009.12. |
| 49. |
Kohei Morita, Hiroki Hibino, Kan Nakatsuji, Fumio Komori, Seigi Mizuno, Satoru Tanaka, Spatially uniform-thick bi-layer graphene on vicinal SiC surfaces, ICSCRM2009, 2009.10. |
| 50. |
Yoshihito Hagihara, Kan Nakatsuji, Fumio Komori, Satoru Tanaka, Rippled Graphene Nanostructures on vicinal SiC surfaces, ICSCRM2009, 2009.10. |
| 51. |
Akihiro Hashimoto, Hiromitsu Tearsaki, Kouhei Morita, Satoru Tanaka and Hiroki Hibino, A breakthrough toward wafer-size bilayer graphene transfer, ICSCRM2009, 2009.10. |
| 52. |
田中 悟, 微傾斜SiC表面上のナノグラフェン構造の形成と物性, 東北大学電気通信研究所・共同プロジェクト研究会「 次世代デバイス応用を企図したグラフェン形成機構の解明及び制御」, 2009.10. |
| 53. |
田中 悟, SiC表面上へのエピタキシャルグラフェンの形成と結晶構造, 日本物理学会第１９回格子欠陥シンポジウム, 2009.09. |
| 54. |
田中 悟，森田康平，萩原好人，スレイ チェンダ, ＳｉＣナノ周期表面上のグラフェンナノ構造, 電気学会光量子デバイス研究会, 2009.09. |
| 55. |
S. Tanaka, K. Motita, S. Chenda, Y. Hagihara, K. Hayashi, S. Mizuno, K. Nakatsuji, F. Komori, Graphene formation on vicinal SiC surfaces, 岡崎Conference, 2009.02. |
| 56. |
Satoru Tanaka, Srey Chenda, Formation of graphene nanowires on vicinal SiC surfaces, MRS 2008 Fall Meeting, 2008.12. |
| 57. |
S. Tanaka, K. Hayashi, K. Motita, S. Chenda, Y. Hagihara, S. Mizuno, H. Hibino, T. Shirasawa, K. Nakatsuji, F. Komori, Uniform thickness distribution of graphene layers on vicinal SiC surfaces, ISGD2008 (2008 International Symposium on Graphene Devices), 2008.11. |
| 58. |
K. Hayashi, ,K. Morita. M. Suzuki, S. Mizuno, S. Tanaka, and H. Tochihara, LEED Analysis of Stacking Sequence of Graphene Layers Formed on Vicinal SiC(0001) Surface, International Symposium on Surface Science and Nanotechnology (ISSS-5), 2008.11. |
| 59. |
田中 悟, SiCナノ表面と表面自己改質によるヘテロ構造の形成, NCCG38, 2008.11. |
| 60. |
Akihiro Hashimoto, Kohsuke Iwao, Satoru Tanaka and Akio Yamamoto, Transfer of Large Area Graphene Sheets from Carbonized 6H-SiC by a Direct Bonding Technique, MRS 2007 Fall Meeting, 2007.11. |
| 61. |
Satoru Tanaka, Masahiro Fujii, Self-ordering of surface nanofacets on vicinal 4H-SiC(0001), Materials Research Society Fall Meeting, 2007.11. |
| 62. |
Akihiro Hashimoto, Kohsuke Iwao, Satoru Tanaka and Akio Yamamoto, A New Formation Method of Large Area Graphene on SiO2/Si Substrate, The 18th European Diamond and Related Materials, 2007.09. |
| 63. |
Akihiro Hashimoto, Kohsuke Iwao, Satoru Tanaka and Akio Yamamoto, Van der Waals Epitaxy of Solid Fullerene on Graphene Sheet, The 18th European Diamond and Related Materials, 2007.09. |
| 64. |
Satoru Tanaka, Masahiro Fujii, Self-ordering of surface nano-facets on vicinal 4H-SiC, ECSCD9, 2007.09. |
| 65. |
Tetsuroh Shirasawa, Kenjiro Hayashi, Seigi Mizuno, Hiroshi Tochihara, Satoru Tanaka, Epitaxial SiO/SiN superstructure on 6H-SiC surface, 第２６回電子材料シンポジウム, 2007.07. |
| 66. |
Masato Ebihara, Satoru Tanaka and Ikuo Suemune, Initial step-flow growth of GaN on Ga-adsorbed SiC nanofacet surfaces, ２００６ Materials Research Society Fall Meeting, 2006.11. |
| 67. |
田中 悟，藤井 政弘，白澤 徹郎，林 賢二郎，水野 清義，栃原 浩, SiC表面上のエピタキシャルSiO/SiN超構造の作製, 2006年SiC研究会, 2006.11. |
| 68. |
H Nakagawa, S Tanaka, Suemune, I, Self-ordering of nanofacets on vicinal SiC surfaces, PHYSICAL REVIEW LETTERS, 2003.11, Vicinal 4H and 6H-SiC(0001) surfaces have been investigated using atomic force microscopy and cross-sectional high-resolution transmission electron microscopy. We observed the characteristic self-ordering of nanofacets on any surface, regardless of polytypes and vicinal angles, after gas etching at high temperature. Two facet planes are typically revealed: (0001) and high index (11 (2) over barn) that are induced by equilibrium surface phase separation. A (11 (2) over barn) plane may have a free energy minimum due to attractive step-step interactions. The differing ordering distances in 4H and 6H polytypes imply the existence of SiC polytypic dependence on nanofaceting. Thus, it should be possible to control SiC surface nanostructures by selecting a polytype, a vicinal angle, and an etching temperature.. |
| 69. |
武内道一, 平山秀樹, 青柳克信, 田中悟, アンチサーファクタントによるGaN層の低転位化, まてりあ, 2001.12. |
| 70. |
T Tawara, Suemune, I, S Tanaka, MOVPE growth of ZnSe/ZnMgS distributed Bragg reflectors with high refractive-index contrast, JOURNAL OF CRYSTAL GROWTH, 2000.06, ZnSe/ZnMgS distributed Bragg reflectors (DBRs) with a high refractive-index contrast were grown on GaAs (1 0 0) substrates by metalorganic vapor-phase epitaxy. The difference of the refractive indices between ZnSe and Zn0.27Mg0.73S was estimated to be about 0.52 at 510 nm, which is very large compared with previous II-VI DBRs. The maximum reflectivity of the grown ZnSe/Zn0.27Mg0.73S DBRs (with only 5-periods) was measured to be 93 % at 510 nm at room temperature. DBRs with a high refractive-index contrast can reduce the penetration depth of light into the DBR and have the potential to increase the strength of the exciton-photon coupling in a microcavity. (C) 2000 Elsevier Science B.V. All rights reserved.. |
| 71. |
P Ramvall, P Riblet, S Nomura, Y Aoyagi, S Tanaka, Optical properties of GaN quantum dots, JOURNAL OF APPLIED PHYSICS, 2000.04, We report on an investigation of the optical properties of GaN quantum dots (QDs) grown by means of metalorganic vapor phase epitaxy. The growth regime for GaN on AlxGa1-xN was observed to change from two- to three-dimensional, forming GaN QDs, when Si was deposited on the AlxGa1-xN surface prior to the GaN growth. These QDs showed a redshift of the photo luminescence (PL) energy from the increased Coulomb energy induced by a compression of the exciton Bohr radius. Furthermore, a diminishing temperature-dependent shift of the PL energy with decreasing QD size caused by a reduction of the longitudinal-optical phonon coupling was found. We also show that the size of the QDs is a critical parameter for the optical nonlinearities. For large dots, the dominant nonlinearity in the PL is the bandgap renormalization but when the size of the dots was reduced below the critical size of 10 nm thick and 30 nm diameter, the state-filling effect became dominant. (C) 2000 American Institute of Physics. [S0021-8979(00)04708-3].. |
| 72. |
H Hirayama, S Tanaka, Y Aoyagi, Fabrication of self-assembling InGaN and AlGaN quantum dots on AlGaN surfaces using anti-surfactant (vol 47, pg 251, 1999), MICROELECTRONIC ENGINEERING, 1999.12, We demonstrate InGaN and AlGaN quantum dots (QDs) formation on AlGaN surfaces vir metal organic chemical vapor deposition (MOCVD). Si anti-surfactant was used in order to modify surface energy balance for changing growth mode from 2-dimensional step-flow growth to 3-dimensional nano-scale island formation. The average lateral size and thickness of the InGaN and AlGaN QDs are 10-20 nm and 5 nm, respectively. Intense photoluminescence (PL) was observed from InGaN QDs even in room temperature. In and Al incorporation in InGaN and AlGaN QDs were estimated to be 22-52% and 1-5%, respectively, from the PL spectrum.. |
| 73. |
T Tawara, S Tanaka, H Kumano, Suemune, I, Growth and luminescence properties of self-organized ZnSe quantum dots, APPLIED PHYSICS LETTERS, 1999.07, Self-organized ZnSe quantum dots (QDs) were grown on (100) ZnS/GaAs surfaces to study the relation of the size dispersion and luminescence. The exact dot sizes were obtained by measurements of atomic force microscope with its tip calibration and transmission electron microscope. The average dot size was 2.0 nm high and 11 nm in its diameter and the density was 1 x 10(10) cm(-2). Transition energies of ZnSe QDs were calculated using these measured dot sizes. These calculated peaks were in reasonable agreement with measured photoluminescence (PL) peaks. It was also revealed that the broadening of the PL spectra from ZnSe QDs were consistently explained by the dot size distribution. (C) 1999 American Institute of Physics. [S0003-6951(99)03928-5].. |
| 74. |
A Petersson, A Gustafsson, L Samuelson, S Tanaka, Y Aoyagi, Cathodoluminescence spectroscopy and imaging of individual GaN dots, APPLIED PHYSICS LETTERS, 1999.06, Uncapped GaN dots on AlGaN barrier material, grown by metal organic chemical vapor deposition on 6H-SiC substrates, were studied. Cathodoluminescence (CL) microscopy and scanning electron microscopy (SEM) were used to investigate both luminescence and structure of individual GaN dots. The correlation between the luminescence and the actual position of self-assembled dots was demonstrated. The position of a dot was established with high resolution SEM and a CL image was used to display the corresponding luminescence. The spectrum from a single dot was obtained by positioning the electron beam on one particular dot. The luminescence from dots with a lateral size of 100 nm and a height of 40 nm was determined to be 3.47 eV. (C) 1999 American Institute of Physics. [S0003-6951(99)05123-2].. |
| 75. |
Suemune, I, A Ueta, A Avramescu, S Tanaka, H Kumano, K Uesugi, Semiconductor photonic dots: Visible wavelength-sized optical resonators, APPLIED PHYSICS LETTERS, 1999.04, Here we describe a strategy toward constructing semiconductor photonic dots in the ultraviolet to blue region. An array of ZnS dots was grown on a GaAs substrate with a selective growth method. The ZnS dots have a pyramidal structure with the base plane of 800 nm square and the height of 300 nm. The {034} crystallographic planes form the sidewalls of the pyramids. Therefore, the size of the pyramidal dots is uniquely determined by the mask patterning. The optical reflection spectra showed clear resonance peaks which are reasonably assigned by the calculation of the resonance modes. Each resonance showed the Q values on the order of 160-300, a reasonable value to observe the modification of the total spontaneous emission rate in this kind of photonic dots. (C) 1999 American Institute of Physics. [S0003-6951(99)03614-1].. |
| 76. |
P Hacke, P Ramvall, S Tanaka, Y Aoyagi, A Kuramata, K Horino, H Munekata, Optical characterization of the "E2" deep level in GaN, APPLIED PHYSICS LETTERS, 1999.01, The correspondence between the E2 level (similar to E-c-0.55 eV) in n-type GaN undergoing thermoionization and photoionization was established. The optical cross section in the vicinity of the threshold for photoionization of this level was measured by means of capacitance transient spectroscopy. Analysis using the formulation of Chantre yielded the optical activation energy, E-0=0.85 eV, and the Franck-Condon parameter, d(FC)=0.30 eV at 90 K. (C) 1999 American Institute of Physics. [S0003-6951(99)03004-1].. |
| 77. |
P Ramvall, S Tanaka, S Nomura, P Riblet, Y Aoyagi, Observation of confinement-dependent exciton binding energy of GaN quantum dots, APPLIED PHYSICS LETTERS, 1998.08, The photoluminescence emission peak energy of GaN quantum dots was observed to shift to higher energy with decreasing quantum dot size. This effect was found to be a combination of a blueshift from the confinement-induced shift of the electronic levels and a redshift from the increased Coulomb energy induced by a compression of the exciton Bohr radius. From this observation, absolute values of the exciton binding energy as a function of quantum dot size are determined. (C) 1998 American Institute of Physics. [S0003-6951(98)03134-9]. |
| 78. |
XQ Shen, S Tanaka, S Iwai, Y Aoyagi, Influence of surface V/III ratio on the film quality during the GaN growth in gas-source molecular beam epitaxy, JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 1998.06, GaN growth was performed on 6H-SiC (0001) substrates by gas-source molecular beam epitaxy (GSMBE), using ammonia (NH3) and solid Ga as V and Ill sources. Two kinds of reflection high-energy electron diffraction (RHEED) patterns, namely (1x1) and (2x2), were observed during the GaN growth depending on the growth conditions, which correspond to nitrogen-rich and Ga-rich surfaces, respectively. Phase diagram of the two surface states via growth conditions was also obtained, indicating the surface V/III. ratio change during the growth. It was found that the GaN film quality was greatly improved under nitrogen-rich growth conditions by X-ray diffraction (XRD) and photoluminescence (PL) characterizations.. |
| 79. |
XQ Shen, S Tanaka, S Iwai, Y Aoyagi, Real-time observations of the GaN dot formation by controlling growth mode on the AlGaN surface in gas-source molecular beam epitaxy, JOURNAL OF CRYSTAL GROWTH, 1998.06, In situ reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM) observations were performed to monitor and characterize the growth processes and surface morphology of GaN on Al(x)Ga(1-x)N surface in gas-source molecular beam epitaxy. It was found that the growth mode can be changed by introducing Si before GaN growth, where the Si is believed to play an important role in the change of the Al(x)Ga(1-x)N surface free energy. Without introducing Si: the GaN growth mode was two-dimensional and (1 x 3) reconstruction was observed. The growth mode of GaN was changed from two-dimensional to three-dimensional by introducing Si on the Al(x)Ga(1-x)N surface. Nanoscale GaN dots were successfully formed on Al(x)Ga(1-x)N/6H-SIC(0 0 0 1) surfaces. Furthermore, the density of the GaN dots was found to be dependent on the amount of Si dose and the growth temperature. (C) 1998 Elsevier Science B.V. All rights reserved.. |
| 80. |
H Hirayama, S Tanaka, P Ramvall, Y Aoyagi, Intense photoluminescence from self-assembling InGaN quantum dots artificially fabricated on AlGaN surfaces, APPLIED PHYSICS LETTERS, 1998.04, We demonstrate photoluminescence (PL) from self-assembling InGaN quantum dots (QDs), which are artificially fabricated on AlGaN surfaces via metalorganic chemical vapor deposition. InGaN QDs are successfully fabricated by the growth mode transition to three-dimensional nanoscale island formation by using "antisurfactant" silicon on AlGaN surface. The diameter and height of the fabricated InGaN QDs an estimated to be similar to 10 nm and similar to 5 nm, respectively, by an atomic-force microscope (AFM). Indium mole fraction of InxGa1-xN QDs is controlled from x = similar to 0.22 to similar to 0.52 by varying the growth temperature of QDs. Intense photoluminescence is observed even at room temperature from InGaN QDs embedded with the GaN capping layers. In addition, from the temperature dependence of the PL-peak energy, we convincingly show that the PL emission actually comes from the InGaN QDs. (C) 1998 American Institute of Physics. [S0003-6951(98)01814-2].. |
| 81. |
XQ Shen, S Tanaka, S Iwai, Y Aoyagi, The formation of GaN dots on AlxGa1-xN surfaces using Si in gas-source molecular beam epitaxy, APPLIED PHYSICS LETTERS, 1998.01, Nanoscale GaN dots were successfully formed on AlxGa1-xN/6H-SiC(0001) surfaces by gas-source molecular beam epitaxy. It was found that the growth mode can be changed by introducing Si before GaN growth, where the Si is believed to play an important role in the change of the AlxGa1-xN surface free energy, Without introducing Si, the GaN growth mode was two dimensional and (1 x 3) reconstruction was observed, The growth mode of GaN was changed from two-dimensional to three-dimensional by introducing Si on the AlxGa1-xN surface. In situ reflection high-energy electron diffraction and atomic force microscopy observations were used to monitor and characterize the growth processes and surface morphology. (C) 1998 American Institute of Physics.. |
| 82. |
S Tanaka, H Hirayama, Y Aoyagi, Y Narukawa, Y Kawakami, S Fujita, S Fujita, Stimulated emission from optically pumped GaN quantum dots, APPLIED PHYSICS LETTERS, 1997.09, Stimulated emission was observed from optically pumped GaN quantum dots in an AlxGa1-xN separate confinement heterostructure fabricated on 6H-SiC(0001) substrate by metal organic chemical vapor deposition. Nanostructural GaN quantum dots, with an average size of similar to 10 nm width, similar to 1-2 nm height, and density of similar to 10(11) cm(-2), were self-assembled on the AlxGa1-xN cladding layer surface. The stimulated emission peak was observed at similar to 3.48 eV, which is similar to 50 meV lower than that of spontaneous emission. The excitation power dependence on the emission intensity clearly indicates threshold pump power density of 0.75 MW/cm(2) for the onset of stimulated emission. (C) 1997 American Institute of Physics.. |
| 83. |
RF Davis, MJ Paisley, Z Sitar, DJ Kester, KS Ailey, K Linthicum, LB Rowland, S Tanaka, RS Kern, Gas-source molecular beam epitaxy of III-V nitrides, JOURNAL OF CRYSTAL GROWTH, 1997.06, Amorphous, hexagonal and cubic phases of BN were grown via ion beam assisted deposition on Si(100) substrates. Gas-source molecular beam epitaxy of the III-V nitrides is reviewed. Sapphire(0001) is the most commonly employed substrate with 6H-SiC(0001), ZnO(111) and Si(111) also being used primarily for the growth of wurtzite GaN(0001) in tandem with previously deposited GaN(0001) or AlN(0001) buffer layers. Silicon(001), GaAs(001), GaP(001) and 3C-SiC(001) have been employed for growth of cubic (zincblende) beta-GaN(001). The precursor materials are evaporated metals and reactive N species produced either via ECR or RF plasma decomposition of N-2 or from ammonia. However, point defect damage from the plasma-derived species has resulted in a steady increase in the number of investigators now using ammonia. The growth temperatures for wurtzite GaN have increased from 650 +/- 50 degrees C to 800 +/- 50 degrees C to enhance the surface mobility of the reactants and, in turn, the efficiency of decomposition of ammonia and the microstructure and the growth rate of the films. Doping has been achieved primarily with Si (donor) and Mg (acceptor); the latter has been activated without post-growth annealing. Simple heterostructures, a p-n junction LED and a modulation-doped field-effect transistor have been achieved using GSMBE-grown material.. |
| 84. |
S Tanaka, S Iwai, Y Aoyagi, Self-assembling GaN quantum dots on AlxGa1-xN surfaces using a surfactant, APPLIED PHYSICS LETTERS, 1996.12, Nanoscale GaN quantum dots were fabricated on AlxGa1-xN layer surfaces via metalorganic chemical vapor deposition. In order to achieve a self-assembling dot structure, a two-dimensional growth mode (step flow) of GaN films on AlxGa1-xN (x=0-0.2) surfaces that is energetically commenced under the conventional growth conditions was intentionally modified into a three-dimensional mode by using a ''surfactant.'' The surfactant is believed to inhibit the GaN film from wetting the AlGaN surface due to the change in surface free energy. The resulting morphological structures of GaN dots were found to be sensitive to the doping rate of tetraethyl silane used as a surfactant, the Al content (x) of the AlxGa1-xN layer, and the growth temperature. A very intense photoluminescence emission was observed from the GaN dots embedded in the AlGaN layers. (C) 1996 American Institute of Physics.. |
| 85. |
MO Aboelfotoh, RS Kern, S Tanaka, RF Davis, CI Harris, Electrical characteristics of metal/AlN/n-type 6H-SiC(0001) heterostructures, APPLIED PHYSICS LETTERS, 1996.11, Metal/A1N/n-type 6H-SiC(0001) heterostructures have been prepared by growing wurtzite AIN layers on vicinal 6H-SiC(0001) using gas-source molecular beam epitaxy, High-resolution transmission electron microscopy results show that the interface between the AlN layer and the Si-terminated 6H-SiC substrate is microstructurally abrupt, but contains defects originating at step sites on the 6H-SiC surface. The interface is found to have a low density of trapped charges of -2 at room temperature without any postgrowth treatment. This value is comparable to 1x10(11) cm(-2) those reported for thermally grown and deposited oxides on n-type 6H-SiC(0001), and indicates the formation of a high quality interface. (C) 1996 American Institute of Physics.. |
| 86. |
RF Davis, S Tanaka, LB Rowland, RS Kern, Z Sitar, SK Ailey, C Wang, Growth of SiC and III-V nitride thin films via gas-source molecular beam epitaxy and their characterization, JOURNAL OF CRYSTAL GROWTH, 1996.07, Silicon carbide (SiC) and aluminum nitride (ALN) thin films have been grown on 6H-SiC(0001) substrates by gas-source molecular beam epitaxy (GSMBE) at 1050 degrees C, Step flow, step bunching and the deposition of 6H-SiC occurred at the outset of the exposure of the (1x1) vicinal substrate surface to C2H4/Si2H6 gas flow ratios of 1, 2 and 10. Subsequent deposition resulted in step flow and continued growth of 6H films or formation and coalescence of 3C-SiC islands using the gas flow ratio of one or the ethylene-rich ratios, respectively. The (3 x 3) surface reconstruction observed using the former ratio is believed to enhance the diffusion lengths of the adatoms, which in turn promotes step flow growth, Essentially atomically flat monocrystalline AIN surfaces were obtained using on-axis substrates. Island-like features were observed on the vicinal surface. The coalescence of the latter features at steps gave rise to inversion domain boundaries (IDBs) as a result of the misalignment of the Si/C bilayer steps with the AIN bilayers in the growing film. The quality of thicker AIN films is strongly influenced by the concentration of IDBs. Undoped, highly resistive (10(2) Omega . cm) and Mg-doped, p-type (0.3 Omega . cm) monocrystalline GaN films having a thickness of 0.4-0.5 mu m have also been grown via the same technique on ALN buffer layers without post-processing annealing.. |
| 87. |
RF Davis, S Tanaka, RS Kern, Microstructural evolution and defect formation during the initial stages of the growth of silicon carbide and aluminum nitride on alpha(6H)-SiC(0001) substrates, JOURNAL OF CRYSTAL GROWTH, 1996.05, The effect of gas flow ratios (C2H4/Si2H6 = 1,2,10) on the growth mode of SiC thin films on vicinal alpha(6H)-SiC(0001) substrates by gas source molecular beam epitaxy (GSMBE) at 950-1150 degrees C has been investigated. Step flow, step bunching and the deposition of 6H-SiC occurred at the outset of the exposure of the (1 x 1) surface to the reactants using any flow ratio. Subsequent deposition resulted in either step flow and continued growth of 6H films using C2H4/Si2H6 = 1 or nucleation and coalescence of 3C-SiC islands on the 6H terraces using C2H4/Si2H6 = 2 and 10. The initial stage of AlN film growth on these substrates and the occurrence of defects has also been investigated. Essentially atomically flat AlN surfaces, indicative of two-dimensional growth, were obtained using on-axis substrates. Island-like features were observed on the vicinal surfaces. The coalescence of the latter features gave rise to double positioning boundaries as a result of the misalignment of the Si/C bilayer steps with the Al/N bilayers in the growing films. The quality of the thicker AlN films was strongly influenced by the concentration of these boundaries. The following sections describe the procedures used to deposit and analyze these two materials as well as detail the results and conclusions of this research.. |
| 88. |
S Tanaka, RS Kern, RF Davis, JF Wendelken, J Xu, Vicinal and on-axis surfaces of 6H-SiC(0001) thin films observed by scanning tunneling microscopy, SURFACE SCIENCE, 1996.04, Surfaces of 6H-SiC(0001) homoepitaxial layers deposited on vicinal (similar to 3.5 degrees off (0001) towards []) and on-axis 6H-SiC wafers by chemical vapour deposition have been investigated using ultra-high vacuum scanning tunneling microscopy. Undulating step configurations were observed on both the on-axis and the vicinal surfaces. The former surface possessed wider terraces than the latter. Step heights on both surfaces were similar to 0.25 nm corresponding to single bilayers containing one Si and one C layer. After annealing at T > 1100 degrees C for 3-5 min in UHV, selected terraces contained honeycomb-like regions caused by the transformation to a graphitic surface as a result of Si sublimation. A model of the observed step configuration has been proposed based on the observation of the ] or [] orientations of the steps and energetic considerations. Additional deposition of very thin (similar to 2 nm SiC films on the above samples by gas source molecular beam epitaxy was performed to observe the evolution of the surface structure. Step bunching and growth of 6H-SiC layers and formation of 3C-SiC islands were observed on the vicinal and the on-axis surfaces, respectively, and controlled by the diffusion lengths of the adatoms.. |
| 89. |
S TANAKA, RS KERN, RF DAVIS, EFFECTS OF GAS-FLOW RATIO ON SILICON-CARBIDE THIN-FILM GROWTH MODE AND POLYTYPE FORMATION DURING GAS-SOURCE MOLECULAR-BEAM EPITAXY, APPLIED PHYSICS LETTERS, 1994.11. |
| 90. |
LB ROWLAND, RS KERN, S TANAKA, RF DAVIS, GAS-SOURCE MOLECULAR-BEAM EPITAXY OF MONOCRYSTALLINE BETA-SIC ON VICINAL ALPHA(6H)-SIC, JOURNAL OF MATERIALS RESEARCH, 1993.11, Single-crystal epitaxial films of cubic beta(3C)-SiC(111) have been deposited on hexagonal alpha(6H)-SiC(0001) substrates oriented 3-4-degrees toward [1120]BAR at 1050-1250-degrees-C via gas-source molecular beam epitaxy using disilane (Si2H6) and ethylene (C2H4). High-resolution transmission electron microscopy revealed that the nucleation and growth of the beta(3C)-SiC regions occurred primarily on terraces between closely spaced steps because of reduced rates of surface migration at the low growth temperatures. Double positioning boundaries were observed at the intersections of these regions.. |
| 91. |
LB ROWLAND, RS KERN, S TANAKA, RF DAVIS, EPITAXIAL-GROWTH OF ALN BY PLASMA-ASSISTED, GAS-SOURCE MOLECULAR-BEAM EPITAXY, JOURNAL OF MATERIALS RESEARCH, 1993.09, Monocrystalline AlN(0001) films with few defects were deposited on vicinal alpha(6H)-SiC(0001) wafers via plasma-assisted, gas-source molecular beam epitaxy within the temperature range of 1050-1200-degrees-C. The Al was thermally evaporated from an effusion cell. An electron cyclotron resonance plasma source was used to produce activated nitrogen species. Growth on vicinal Si(100) at 900-1050-degrees-C resulted in smooth, highly oriented AlN(0001) films.. |
| 92. |
RS KERN, LB ROWLAND, S TANAKA, RF DAVIS, SOLID-SOLUTIONS OF ALN AND SIC GROWN BY PLASMA-ASSISTED, GAS-SOURCE MOLECULAR-BEAM EPITAXY, JOURNAL OF MATERIALS RESEARCH, 1993.07, Solid solutions of aluminum nitride (AlN) and silicon carbide (SiC), the only intermediate phases in their respective binary systems, have been grown at 1050-degrees-C on alpha(6H)-SiC(0001) substrates cut 3-4-degrees off-axis toward [1120BAR] using plasma-assisted, gas-source molecular beam epitaxy. A film having the approximate composition of (AlN)0.3(SiC)0.7, as determined by Auger spectrometry, was selected for additional study and is the focus of this note. High resolution transmission electron microscopy (HRTEM) revealed that the film was monocrystalline with the wurtzite (2H) crystal structure.. |
| 93. |
LB ROWLAND, RS KERN, S TANAKA, RF DAVIS, ALUMINUM NITRIDE SILICON-CARBIDE MULTILAYER HETEROSTRUCTURE PRODUCED BY PLASMA-ASSISTED, GAS-SOURCE MOLECULAR-BEAM EPITAXY, APPLIED PHYSICS LETTERS, 1993.06, Pseudomorphic structures containing beta(3C)-SiC and 2H-AlN have been grown on vicinal alpha(6H)-SiC(0001) at 1050-degrees-C by plasma-assisted, gas-source molecular beam epitaxy. Reflection-high energy electron diffraction and cross-sectional high-resolution transmission electron microscopy showed all layers to be monocrystalline. The AlN layers were uniform in thickness. Defects in these layers initiated at steps on the 6H-SiC film. The 3C-SiC layers contained a high density of stacking faults and microtwins caused primarily by the interfacial stresses generated by the mismatch in lattice parameters between AlN and beta-SiC coupled with the very low stacking fault energy of SiC. This is the first report of the deposition of single crystal SiC/AlN/SiC thin film heterostructures on any substrate as well as the first report of the epitaxial growth of single crystal layers of binary materials with three different crystal structures.. |
| 94. |
JJ SUMAKERIS, LB ROWLAND, RS KERN, S TANAKA, RF DAVIS, LAYER-BY-LAYER GROWTH OF SIC AT LOW-TEMPERATURES, THIN SOLID FILMS, 1993.03, A novel reactor for layer-by-layer deposition of compound semiconductors has been designed and commissioned for the deposition of SiC. The substrates rested on a heated, rotating platform. They encountered individual fluxes of Si2H6 and C2H4 and subsequently paused beneath a hot filament. The filament was used to encourage the surface reaction between silicon adatoms and carbon precursors. Heteroepitaxial films were grown between 850 and 980-degrees-C on Si(100) substrates oriented 3-degrees off-axis toward [011]. They were analyzed for composition, crystallinity, growth per cycle, and morphology using depth profiling Auger spectroscopy, reflection high-energy electron diffraction, ellipsometry and transmission electron microscopy. Growth, as measured by ellipsometry and transmission electron microscopy, corresponded to approximately one monolayer per cycle. Monocrystalline films were achieved. Initial growth and characterization results of representative films are presented and discussed.. |
| 95. |
RC GLASS, LM SPELLMAN, S TANAKA, RF DAVIS, CHEMICAL AND STRUCTURAL-ANALYSES OF THE TITANIUM NITRIDE/ALPHA (6H)-SILICON CARBIDE INTERFACE, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS, 1992.07, Ion-assisted reactive evaporation (IARE) using low-energy (100 eV) nitrogen ions was employed to deposit TiN films onto the vicinal Si-terminated (0001) face of alpha(6H)-SiC single crystals at 350-degrees-C in an ultrahigh vacuum chamber operated at a working pressure of 2 X 10(-4) Torr. The initial exposure of the SiC surface to nitrogen ions for a 2-min period resulted in Si-N bonding. This exposure was also an important step in attaining ohmic contact properties at low temperature, and the formation of a thin (almost-equal-to 5-15 angstrom) amorphous layer at the interface. The disorder was maintained after the deposition of 5 angstrom of TiN. The TiN contacts were ohmic after deposition; they showed little change in microstructural or electrical properties after annealing at 450, 550, and 600-degrees-C for 15-30 min. The results of this research indicate that a metal-insulator-semiconductor structure was responsible for obtaining the contact properties.. |
| 96. |
S TANAKA, H KOMIYAMA, GROWTH-MECHANISM OF SILICON-CARBIDE FILMS BY CHEMICAL VAPOR-DEPOSITION BELOW 1273-K, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 1990.10. |
