Breakdown of the quantized Hall effect in the vicinity of current contacts
Breakdown of the quantized Hall effect in the vicinity of current contacts
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电流触点附近量子霍尔效应的击穿
DOI：
10.1103/physrevb.61.2931
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发表时间：
2000
影响因子：
3.7
通讯作者：
S. Komiyama
中科院分区：
文献类型：
--
作者：
Y. Kawano;S. Komiyama
研究了非平衡电子在1.5 mm宽的霍尔棒上量子霍尔效应(QHE)下的回旋辐射的空间分布。在两端电阻被量子化的小电流水平下，在金属电流接触和二维电子气(2DEG)层之间形成的电子入射和出射拐角处观察到回旋发射(CE)。随着电流的增加，额外的CE出现在与电子进入角相反的源极触点的拐角附近。附加的CE伴随着有限的电压降。发生有限压降的区域局限于观察到CE的源极接触附近的有限区域，并表明QHE在源极接触附近局部击穿，然后在整个2DEG沟道中发生击穿。器件宽度依赖关系的研究表明，源接触附近的量子赫兹局部击穿只发生在足够宽的霍尔棒中(宽度远大于200μm)。通过假设电子-空穴对是在级联过程中产生的，从而合理地解释了所有实验观察到的特征，这是由于金属源接点与二维电子气之间的界面上形成了强烈的极化场。
Spatial distribution of the cyclotron radiation emitted from nonequilibrium electrons is studied on 1.5 mm-wide Hall bars in the quantized Hall effect (QHE) regime. At low-current levels where the two terminal resistance is quantized, the cyclotron emission (CE) is observed at the electron entry and exit corners formed between the metallic current contacts and the two-dimensional electron gas (2DEG) layer. As the current increases, additional CE occurs in the vicinity of the corner of the source contact that is opposite to the electron entry corner. The additional CE is accompanied by a finite voltage drop. The region over which the finite voltage drop takes place is localized to the limited region adjacent to the source contact where the CE is observed, and shows that the QHE breaks down locally in the vicinity of the source contact before the breakdown develops in the entire 2DEG channel. Studies of device-width dependence reveal that this local breakdown of the QHE in the vicinity of the source contact takes place only in sufficiently wide Hall bars (with a width well larger than 200 μ m). All the experimentally observed features are reasonably interpreted by assuming that electron-hole pairs are generated in cascading process due to strong polarization fields formed along the interface between the metallic source contact and the 2DEG.