Terahertz response in the quantum-Hall-effect regime of a quantum-well-based charge-sensitive infrared phototransistor
Terahertz response in the quantum-Hall-effect regime of a quantum-well-based charge-sensitive infrared phototransistor
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DOI：
10.7567/jjap.57.04fk04
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发表时间：
2018-03
影响因子：
1.5
通讯作者：
D. Nakagawa;K. Takizawa;K. Ikushima;Sunmi Kim;M. Patrashin;I. Hosako;S. Komiyama
中科院分区：
文献类型：
--
作者：
D. Nakagawa;K. Takizawa;K. Ikushima;Sunmi Kim;M. Patrashin;I. Hosako;S. Komiyama
研究了基于GaAs/AlGaAs多量子阱（QW）结构的电荷灵敏红外光电晶体管（CSIP）在磁场作用下的特性。在CSIP中，上量子阱用作通过光激发充电的浮栅。光生电荷的检测使用的最低量子阱导电通道的电阻。在垂直强磁场中，导电沟道表现出整数量子霍尔效应（QHE），产生太赫兹（THz）响应ΔR的磁场依赖性。我们发现ΔR有两个不同的特征。一个是ΔR在QHE平台上切换符号，这可以简单地解释为导电通道中的电子密度增加。另一个特征是当在导电沟道中形成势垒时，观察到增强的正ΔR。后一种机制可以解释为由于光致电荷的边缘/体散射的促进。这些发现提出了通过使用磁场和势垒来增强THz响应的方法。
The characteristics of a charge-sensitive infrared phototransistor (CSIP) based on a GaAs/AlGaAs multiple quantum-well (QW) structure are studied under a magnetic field. In the CSIP, the upper QWs serve as a floating gate that is charged by photoexcitation. The photoinduced charges are detected using the resistance of the lowest QW conducting channel. The conducting channel exhibits the integer quantum Hall effect (QHE) in a perpendicular high magnetic field, yielding the magnetic field dependence of the terahertz (THz) response ΔR. We found two different features of ΔR. One is that ΔR switches sign across the QHE plateau, which is explained simply by an increased electron density in the conducting channel. The other feature is observed as an enhanced positive ΔR when a potential barrier is formed in the conducting channel. The latter mechanism can be interpreted as the promotion of edge/bulk scattering due to photoinduced charges. These findings suggest ways to enhance the THz response by using magnetic fields and potential barriers.