HIGH FREQUENCY CONDUCTIVITY OF GROUND LANDAU LEVELS IN SILICON MOS TWO DIMENSIONAL ELECTRON SYSTEMS

硅MOS二维电子系统中地朗道能级的高频电导率

• 批准号: 05640387
• 负责人: WAKABAYASHI Junichi
• 金额: $ 1.41万
• 依托单位: CHUO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05640387/
• 关键词: Two Dimensional Electron systems; Landau levels; AC conductivity; Silicon MOS; Electron Localization

The electronic transport properties of two-dimensional systems of a silicon MOS (Metal-Oxide-Semiconductor) structure under strong magnetic fields wewe investigated using AC conductivity measurements. Frequnecy dependence and temperature dependence of sigma _<xx> in the ground Landau levels and the first excited Landau levels has been measured at frequncy between 100 kHz and 10 MHz and at a temperature between 0.4K and 1.5K in a magnetic field of 8T.Both results of frequncy and temperature dependence in the ground Landau levels, where the conductivity exhibits low values, have shown that the electronic transport was dominated by the variable range hopping. Results in the gap regions between the adjacent Landau levels in the first excited Landau levels have also shown that the electronic tarnsport was dominated by variable range hopping. It was first demonstrated that the frequency dependence in the two dimensional electron systems obey the scaling law observed in three dimensional hopping systems.Results in the peak of the first excited Landau levels have shown that there have been a considerable contribution of the hopping transport underling the transport in the extended states near the center of the Landau level.

利用交流电导测量方法研究了强磁场下硅MOS（Metal-Oxide-Semiconductor）结构二维系统的电子输运性质。在<xx>8 T的磁场中，在100 kHz ~ 10 MHz的频率和0.4 K ~ 1.5 K的温度范围内，测量了基态朗道能级和第一激发态朗道能级的σ_2随频率和温度的变化关系.在电导率较低的基态朗道能级，σ_2随频率和温度的变化关系表明，电子输运以变程跳跃为主.第一激发态朗道能级中相邻朗道能级间的差距也表明电子输运以变程跳跃为主。首次证明了二维电子系统的频率依赖性服从三维跳跃系统的标度律，第一激发朗道能级峰的结果表明，在朗道能级中心附近的扩展态输运中，跳跃输运对输运有相当大的贡献。