The influence of the Cu doping position on GaAs: First-principles calculations

The structural, electronic, and optical properties of GaAs doped with two Cu atoms at different depths was studied using first-principles calculations based on the HSE hybrid density functional theory. The optical properties, including the complex dielectric function, optical refractive index, extinction coefficient, and absorption coefficient were computed for radiation with an energy of up to 6.7 eV. The results show that the characteristics of the GaAs system change when the Cu atoms are doped at different depths. When the two Cu atoms are placed 5.653 angstrom or 2.827 angstrom from the surface of the GaAs crystal, it exhibits typical semi-metallic properties. However, the Cu doping depth has little effect on the band structure and properties of the materials. When Cu atoms are doped onto the GaAs surface, the material shows the band structure characteristics of a metal conductor. The linear optical behavior of the GaAs system, which corresponds to its electronic structure, also varies depending on the doping position. The contribution of Cu-3d orbital electrons to the material properties varies with the doping position. In addition, copper atoms doped at a greater depth have a greater influence on the absorption wavelength and intensity of the material.