Suppression of current shot noise level in semiconductor multiple junctions

由于散粒噪声是电子装置中的主要噪声源之一，因此对于诸如场效应晶体管、激光器和发光二极管（LED）的半导体装置的架构，期望抑制散粒噪声。近年来，由于多隧道结的库仑充电效应，人们提出了抑制多隧道结电流中散粒噪声的方法，本研究从实验上研究了利用半导体多隧道结抑制散粒噪声的可能性。为了阐明MTJ的噪声抑制，我们评估了来自与MTJ直接连接的LED的光子数波动（Fano因子）。首先，我们采用分子束外延和湿法化学腐蚀技术制备了N ×（n-GaAs/i-AlGaAs）隧道器件，其中N为势垒数。当N ×（MTJ）的电阻比LED的微分电阻大20倍时，我们发现在室温下Fano因子中出现1/N噪声抑制现象，并用Langevin方程方法研究了LED中光子数涨落的分析，实验结果与理论分析一致。当多重隧道结的电阻远大于发光二极管的微分电阻时，因此，对于抑制散粒噪声，MTJ在半导体器件中是有希望的。

As the shot noise is one of the main noise sources in electronic devices, the suppression of a shot noise is expected for the architecture of semiconductor devices, such as a field effect transistor, a laser, and a light emitted diode (LED). Recently, the suppression of the shot noise level in current flow from the multiple tunnel junction (MTJ) was proposed, due to the coulomb charging effect at each tunnel junction.In this research, we experimentally investigated the possibility of noise suppression by using the semiconductor multiple tunnel junctions. In order to clarify the noise suppression by MTJ, we evaluated the photon number fluctuation (Fano Factor) from a LED, which is directiy connected with the MTJ. First, we prepared N×(n-GaAs / i-AlGaAs) tunnel devices by Molecular Beam Epitaxy and the wet chemical etching technique, where N is the number of barriers. When the N×(MTJ) whose resistance is by 20th much larger than the differential resistance of LED is connected with LED, we found the occurrence of the 1/N noise suppression in Fano Factor at room temperature.We also have been investigated the analysis of photon number fluctuation in LED in terms of the Langevin-equation method As a results, our experirnental results is in accordance with theoretical one, when the resistance of the multiple tunnel junction is much larger than the differential resistance of LED. Therefore, for the suppression of the shot noise, the MTJ is promising in semicbnductor devices.