Suppression of current shot noise level in semiconductor multiple junctions

由于散粒噪声是电子器件的主要噪声源之一，因此对场效应晶体管、激光器和发光二极管等半导体器件的结构进行散粒噪声的抑制是人们所期望的。近年来，由于多隧道结处的库仑充电效应，提出了抑制多隧道结电流中散粒噪声电平的方法。在本研究中，我们通过实验研究了利用半导体多隧道结抑制噪声的可能性。为了阐明MTJ对噪声的抑制作用，我们评估了与MTJ直接相关的LED的光子数波动（Fano因子）。首先，我们采用分子束外延和湿化学蚀刻技术制备了nx （N - gaas / i-AlGaAs）隧道器件，其中N为势垒数。当电阻比LED差分电阻大20倍的nx （MTJ）与LED连接时，我们发现室温下Fano因子出现1/N的噪声抑制。我们还研究了用langevin方程方法分析LED中光子数波动的情况，结果表明，当多隧道结的电阻远大于LED的微分电阻时，我们的实验结果与理论结果一致。因此，在抑制弹丸噪声方面，MTJ在半导体器件中具有广阔的应用前景。

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.