Edge States in Two-Dimensional Electron Gas Systems at High Magnetic Fields Studies in Terms Spectroscopic Approach.

1. 边缘态色散关系：与非平衡边缘态分布相关的输运特性表明，在0.1K以下的低温度下，边缘态由可压缩区和不可压缩区组成，但在B=3T.2时，色散随着T的增加而趋于平滑，直至0.5K。边缘态和体态：考虑到多余的边缘电荷，一个一致的计算导出了由化学势引起的边缘电流和由静电势引起的霍尔电流之间的比率。此外，由于所有电子对施加的扰动作出响应而产生的“响应电流”与由于电子在费米表面上的概率幅值产生的电流而产生的“费米表面电流”相区别。这两种输运电流的定义分别产生了量子化霍尔效应（QHE）的体图和边缘图。量子霍尔效应（QHE）中能量耗散的机制和位置(1)为了使有针对性的研究成为可能，研制了远红外（FIR）超高灵敏度探测器。通过使用QHE器件，实现了比传统锗光导探测器高3个数量级以上的灵敏度。(2)利用上述探测器探测到了QHE状态下无耗散的二维电子气体（2DEG）的回旋辐射。对3000多个小霍尔棒阵列的研究表明，发射存在一个阈值霍尔电压；eV_H = homega_c / 2。结果表明，该发射与触点的电子注入有关，有助于更好地理解触点和2DEG体系之间的电子交换机制。QHE击穿的非局域性：对霍尔棒中纵向电场空间演化的研究表明，自举式电子加热导致QHE击穿。

1. Dispersion relation of edge states : Transport characteristics associated with non-equilibrium edge state distribution indicated that the edge states consist of compressible and incompressible regions at low T below 0.1K but the dispersion smoothes with increasing T up to 0.5K at B=3T.2. Edge states and bulk states : A consistent calculation taking the excess edge charges into account derived the ratio between the edge current due to chemical potential and the Hall current due to electrostatic potential. Also, the "response current" due to all the electrons responding to the imposed perturbation was distinguished from the "Fermi-surface current" due to the current of the probability amplitude of the electrons on the Fermi surface. These two are alternative definitions of transport current, which lead to the bulk picture and the edge picture of the quantized Hall effedts (QHE), respectively.Mechanism and location of energy dissipation in the Quantum Hall effects (QHE)(1) Ultra-high sensitive detectors in the far-infrared (FIR) range were developed to make the aimed studies possible. By using QHE devices, a sensitivity by more than three orders of magnitude higher than that of the conventional Ge photoconductive detectors was achieved.(2) The cyclotron emission from dissipation-less two-demensional electron gas (2DEG) in the QHE regime was detected by the detectors above. Studies on an array of more than 3000 small Hall bars revealed that there is a threshold Hall voltage for the emission ; eV_H=homega_c/2. The results show that the emission is associated with the injection of electrons from contacts, and contributed to better understanding of the mechanism of exchange of electrons between contacts and the 2DEG system.4. Nonlocal nature of the breakdown of the QHE : Studies of spatial evolution of longitudinal electric field in Hall bars indicated that the bootstrap-type electron heating causes the QHE to breakdown.