表面科学
Online ISSN : 1881-4743
Print ISSN : 0388-5321
ISSN-L : 0388-5321
21 巻 , 12 号
選択された号の論文の9件中1~9を表示しています
巻頭言
特集 : SiC素子実用化のための表面研究
  • 吉田 貞史
    2000 年 21 巻 12 号 p. 764-770
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    Recently, wide bandgap semiconductors, like silicon carbide (SiC), nitrides and diamond have been intensively studied for high power, high frequency devices and/or devices operating at high temperatures. SiC has 2∼3 times larger bandgap energy, about 10 times larger breakdown voltage, about 2 times larger saturated electron drift velocity and about 3 times larger thermal conductivity than those of Si. These excellent physical and electrical properties make it possible to fabricate electronic devices with superior specifications compared with Si devices. However, there still remain a lot of problems in their device processes to be solved for realizing SiC devices, most of which are closely related to surface sciences of SiC. In this paper, the characteristics of SiC semiconductor and its application fields are briefly described, and then the issues in the SiC device processes are pointed out.
  • 高橋 邦方, 北畠 真
    2000 年 21 巻 12 号 p. 771-777
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    Epitaxial growth of silicon carbide (SiC) by “Vertical hot-wall type chemical vapor deposition (CVD)” has been investigated. Higher growth rates over 10μm/h has been realized at a growth temperature of 1700oC. The surface morphology has been observed by atomic force microscopy to examine formation of macroscopic steps. In addition to conventional (0001) face, 6H- and 4H-SiC epitaxial layers with smooth surfaces have been realized on (11-20) and (1-100) faces. Crystallographical quality of epitaxial layers has been evaluated by X-ray diffraction. Furthermore, we developed a novel doping method, “Pulse doping”, during epitaxial growth for a well-controlled doped layer. A pulse valve that could open and close within a very short period less than 10 μs was used in this study to supply the dopant gases. Carrier concentrations of the doped layers have been precisely controlled, and their abrupt doping profiles have been achieved.
  • 伊藤 久義, 大島 武
    2000 年 21 巻 12 号 p. 778-783
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    Research and development of ion implantation technique for SiC semiconductor have been performed. Hot-implantation of P ions into 6H-SiC raises the electron concentration in P-implanted n-type layers, showing that the hot-implantation enhances the electrical activation of P donors. The hole concentration in Al ion implanted 6H-SiC is found to increase due to co-implantation of C ions. This fact demonstrates that the electrical properties of Al-implanted p-type layers are improved by the C co-implantation. Using the ion implantation methods, SiC-based metal-oxide-semiconductor field-effect-transistors (MOSFETs) have been successfully fabricated. These results indicate that hot- and C co-implantations are quite useful for the fabrication of SiC devices.
  • 土田 秀一, 直本 保, 鎌田 功穂, 泉 邦和
    2000 年 21 巻 12 号 p. 784-790
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    The effects of H2- and HF- on SiC{0001} surfaces interms of morphology and adsorbates have been investigated. High temperature annealing in a H2 ambient produces a flat surface without macro-step bunching for on-axis 6H-SiC(0001) and 8° off 4H-SiC(0001). Fourier-transformed infrared attenuated total reflection (FTIR-ATR) spectra show that surface Si-H bonds are formed on 6H-SiC(0001) and surface C-H bonds are formed on SiC(000¯1) by H2 treatments. The sequence of thermal oxidation and HF etching also produces on-axis 6H-SiC(0001) with a stepped morphology; however, the density of surface Si-H bonds on the SiC(0001) surface after this treatment is lower than our detection limit. The chemical characteristics of surface Si-H bonds on SiC(0001) formed by H2 treatment has also been discussed.
  • 原 史朗
    2000 年 21 巻 12 号 p. 791-799
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    We report the Schottky limit and a charge neutrality level (CNL) experimentally demonstrated at metal/6H-SiC (0001) interfaces. A passivated SiC surface with an almost flat band was formed by dipping the substrate in boiling pure water before metallization. The total density of interface states was 4.6 × 1010 states · cm-2/eV, indicating that the density of the metal induced gap states (MIGS) was less than this value. In contrast, at incompletely passivated interfaces without the boiling water dipping process, a broad continuum of interface states was observed with the CNL located at 0.797 eV from the conduction band minimum. The origin of these interface states was found to be in the disordered interface layers.
論文
  • 鍛治 裕之, 下山 雄平
    2000 年 21 巻 12 号 p. 800-805
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    Using the dilution technique of developing solution and the flow-orientation method, we successfully fabricated a well-defined Langmuir monolayer and Langmuir-Blodgett (LB) films of 4-dimethylamino-4'-nitrostilbene (DANS). The dilution technique of developing solutions allows formation of a two-dimensional film of DANS below the certain concentration. X-ray diffraction (XRD) and ultraviolet visible (UV-VIS) spectroscopy revealed the LB film structures. The XRD data indicated that DANS tilted at an angle of 10 degrees to the normal of the substrate. The UV-VIS spectra of the LB films showed molecular organization with a stable condensed phase. The spectral peaks from the LB films shifted to a shorter wavelength as compared with those from DANS solution. The blue shift of the UV-VIS spectra may reflect intermolecular stacking of nitrostilbene chromophore, and consequently formation of a π-electron band.
  • 戸津 美矢子, 高橋 元幾, 星 孝弘, 広川 吉之助
    2000 年 21 巻 12 号 p. 806-815
    発行日: 2000年
    公開日: 2007/04/06
    ジャーナル フリー
    TOF-SIMS fragment patterns of organic polymers: poly (tetrafluoro ethylene), poly vinyl fluoride, poly vinyl chloride etc., can be qualitatively inferred. Considering empirical characteristics of the elements forming these compounds: electron affinity, binding energy and so on, a simple rule to infer fragmentation of these organic polymers, especially poly vinyl halogen compounds, is suggested.
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