Self-consistent solution of Schrodinger-Poisson equations in a reverse biased nano-scale p-n junction based on Si/Si0.4Ge0.6/Si quantum well

摘要

In this paper, the quantum mechanical behavior of a reverse biased nano-scale p-n junction based on Si/Si0.4Ge0.6/Si quantum well has been studied by obtaining the self-consistent solution of coupled Schrodinger and Poisson equations. The carrier confinement within the said quantum well structure has been investigated by analyzing the special variations of electron and hole densities throughout the device structure obtained from the self-consistent solution of coupled Schrodinger and Poisson equations for different widths of the quantum well. The tunnel current across the junction has also been calculated for the heterostructure for different applied reverse bias voltages. Results show that, due to the greater depth of the quantum well in conduction band as compared to that in valance band of Si/Si0.4Ge0.6/Si heterostructure, the quantum confinement effect is more pronounced for electrons in conduction band as compared to that for holes in valance band. Finally the current-voltage characteristics of the heterostructure under consideration have been investigated for different widths of the quantum well. It is observed that the modulation of tunnel current may be achieved by varying the width of the quantum well. The present study is the groundwork for investigating the optoelectronic properties of nano-scale photodetectors based on Si/Si1-xGex/Si material system capable of detecting longer wavelengths around 1.30 and 1.55 mu m.