Effects of co-doping on electronic structure and optical properties of 3C-SiC from first-principles method

Abstract

Electronic structure and optical properties of Cr-, Al- and Cr-Al co-doped 3C-SiC systems are investigated by the first principles method. Al-, Cr- and Cr-Al co-doped systems present the characteristics of p-, n- and n-type semiconductor materials, respectively. Charge density difference results show that the covalency of bonding reduces after doping, which is verified by bond population values due to the fact that the values of single doped and Cr-Al co-doped systems are lower than that of un-doped 3C-SiC. The intrinsic 3C-SiC barely has microwave dielectric loss, however, it can be improved through Al or Cr doping, especially the effect of Al doping, indicating the enhanced ability of materials to absorb electromagnetic waves, which is helpful for SiC to be widely used in military and aerospace fields as absorbing materials. By analyzing the host peaks of the absorption coefficient and the loss function, it is found that there is a significant red shift after doping. SiC exhibits the “Transparent Type” characteristic based on the fact that it has a lower absorption coefficient and reflectance in the visible light region, which proves the foundation for optical property and opens a window for photoelectric devices.