Study of Backscattering Phenomenon from Drain Region of Silicon Decanano Diode Using Nonequilibrium Green's Function Approach

Abstract

Scattering within a channel region of a decanano device has been focused on so far. However, it was found in our previous research that the backscattering from a drain region of such a decanano device markedly affects AC device characteristics. Therefore, we have investigated the backscattering phenomenon from the drain region of a silicon decanano diode at the level of electron wave behavior using nonequilibrium Green's function (NEGF) approach for the first time. The numerical experiment without scattering in the device reveals that there is an inevitable accumulation of electron charge near the drain in the channel, which might degrade the AC performance of the device, even without scattering in the device. Moreover, the numerical experiment with scattering in the device reveals that the backscattered (BS) ratio from the drain region increases with decreasing drain voltage. The amount of electron caused by scattering within the channel increases with increasing drain voltage, whereas the amount of electron caused by backscattering from the drain region increases with decreasing drain voltage. This is why the BS ratio from the drain region, which is an indicator of AC performance, increases with decreasing drain voltage. Since very low voltage operation is required for future ultralow power devices, the obtained result is very important and the analysis of the backscattering phenomenon from the drain region becomes more beneficial.