The Numerical Calculation Of Ge_1-xSn_x Band Structure Based On First-principles

Moore's Law, driven by the integrated circuit industry into the era of 16 nm process, the source and drain Si-MOSFET device, the channel in use strain Si, Ge and other materials can not meet the current performance of the device performance and power requir ements. Ge Sn alloy material having a Sn adjustable component, and exhibits of the MOSFET device when it is used as a high-mobility channel material properties make it a new hotspot. Experimental results show that the common Ge material is indirect band gap semiconductor, but its Sn doped, and the compositional ratio of around 10%, the energy band structure properties Ge Sn alloy material will occur from direct band gap to indirect band transition gap. This property and its optoelectronic integrated circuit device as a light emitting material provides a broad application prospects.This article is based on first-principles approach to structural optimization of cell Ge Sn Sn alloy composition under different energy band structure, the band gap, the total density of states, projected density of states, effective mass, mobility, elastic constants and Young's modulus of the numerical study, to achieve the desired purpose. Before the numerical calculation, the paper according to the principle of minimum energy cell structure Ge Sn alloy depth optimization, has been optimized in this follow-up study will be calculated in good agreement with the experimental values on the model.In this paper, the calculation of the band structure concluded Sn components increases, the band gap Ge1-x Snx alloy will show the overall downward trend in the group was divided into 5% Sn nowadays by density functional theory, there will be a band gap of extreme value.When the conclusion in the study of the changing nature of the bandgap Ge Sn alloy, the Sn component in proportion to around 10%, which will take place from indirect bandgap bandgap transition to direct band gap, which is the same as the results in the literature also affirmed the value of Ge Sn alloy photovoltaic integrated circuits. State density and projected density of states is also important for the material properties, the density of states and the results of the projected density of states under different Sn components from microscopic point of view to verify the nature Ge Sn bandgap material.By quadratic curve fitting to calculate the effective mass and in accordance with its relationship with mobility mobility can be calculated in different Sn alloy components Ge Sn under. The results show that when the Sn component changes, the carrier mobility with increasing Sn alloy Ge Sn component x increasing trend presentation. This paper also study the relevant basic parameters required for the calculation of strain, elastic constants obtained at different Sn components Ge1-x Snx materials, bulk modulus, shear modulus and Young's modulus calculations, these calculations It provides a good theoretical data support for in-depth study of the subsequent strain engineering.