Quantum mechanical simulation of current noise of nanoscale double-gate MOSFETs

在本研究项目中，我们利用基于非平衡态格林函数模型(NEGF)的量子输运模型和量子修正的蒙特卡罗(MC)器件模拟，研究了纳米MOS器件的电流噪声特性。用非平衡态格林函数模型研究了半导体纳米器件中电子的量子力学关联对散粒噪声的抑制，从而讨论了低温下的电流噪声。将NEGF模型应用于弹道纳米级Si-MOSFET中的散粒噪声研究是很有意义的，其中当不同形状的电极的三维电子被注入到沟道的反型层中并被限制在量子化的子带中作为所谓的二维电子气时，电子的关联有望存在。模拟结果表明，漏极电流噪声总是被抑制在全Pois…以下更高的Sonian值，部分是由于费米关联，部分是由于从电极注入的电子的分配噪声。此外，随着栅偏压的增加和工作温度的降低，电流噪声与平均电流之比(Fano因子)被强烈地抑制。量子修正蒙特卡罗模型发展起来的量子修正MC模型可以模拟实际半导体器件在常温下的电流起伏，并应用于研究纳米级双栅Si-MOSFET的电流起伏。在这个粒子模型中，量子力学效应以势的量子修正的形式被结合进来。结果表明，硅导带椭球多谷的引入和能量量子化效应是分析超小硅MOSFET电流噪声的重要因素。结果发现，即使沟道长度减小到几十纳米以下，电流噪声的分数偏差也不会增加S，而是略有减小。较少

In this research project, we have studied the current noise characteristics of nano-scale MOS devices by employing the quantum transport models based upon the nonequilibrium Green's function model (NEGF) and the quantum corrected Monte Carlo (MC) device simulation.1. Nonequilibrium Green's function modelThe NEGF is used to study the shot noise suppression caused by the quantum mechanical correlations of electrons in semiconductor nano-scale devices, so that the current noise is discussed at low temperature. It was considered interesting to apply the NEGF models to the study of shot noise in ballistic nano-scale Si-MOSFETs, where correlations of electrons are expected to exist when the three dimensional electrons in the various shape of electrodes are injected into the inversion layer of the channel and confined to quantized subbands as the so-called two-dimensional electron gases. It is found from the NEGF simulation that the drain current noise is always suppressed below the full Pois … More sonian value partly due to the Fermi correlation and partly due to the partition noise of electrons injected from the electrodes. Further, the current noise to average current ratio (Fano-factor) is found to be suppressed strongly with the increase of gate bias and the decrease of operating temperature.2. Quantum corrected Monte Carlo modelThe quantum corrected MC model has been developed to simulate practical semiconductor devices at normal temperatures, and applied to the study of the current fluctuations of a nano-scale double-gate Si-MOSFET. The quantum mechanical effects are incorporated in terms of a quantum correction of potential in this particle model. It is shown that the incorporation of the ellipsoidal multi-valleys of silicon conduction band and energy quantization effects are important to analyze the current noise in ultra small Si-MOSFETs. As a result, it is found that the fractional deviation of current noise never increase s but decreases a little even if the channel length is reduced to less than a few ten nanometers. Less