Electronic Structure And Optical Properties Of GaAs_1-xBi_x

In recent years, the rapid development of information technology led to the rapid development of optoelectronic materials and devices. GaAsBi semiconductor optoelectronic material has good electronic and optical properties, which make it suitable for long wavelength emission devices.In this paper, first-principles based on density functional calculations have been performed to investigate the model building, geometry optimization, electronic structure and optical properties of bismuth alloying in GaAs. We choose V group elements Bi as doping elements in the study. The paper can be divided into two parts:GaAsBi bulk and nanowires. The main work is as follows,1. During the modeling and testing, we use different functional tests to select a reasonable description of exchange-correlation as the calculation standard. Build and optimize the doping models.2. Analyze the energy band structure, and it can be found that the band gap of GaAs1-xBix shrinks clearly with the increasing Bi concentration. Take into account of the heavy elements Bi, the spin-orbit coupling (SOC) effect is considered in the calculations.3. The total density of states and partial density of states are discussed in detail in order to reveal the relationship between the electronic and optical properties. The most important is that both in GaAsBi bulk and nanowires, the Bi6p states showed a dominate contribution for the electronic structure around Fermi level.4. The paper systematically analyzes the GaAsBi optical properties. The main parameters include the imaginary part of the dielectric function ε2(ω), optical absorption spectra α(ω), the energy loss spectrum L(ω), the reflectivity R(ω), etc. The optical transition of Bi doping in GaAsBi alloy exhibits a red shift, which has a close relationship with the shrinking band gap caused by the Bi6p state.