Structural, electronic and optical properties of B, N and Ni-doped zinc-blende GeC by first-principles calculation

The structural, electronic and optical properties of intrinsic and doped (B, N, and Ni) zinc-blende germanium carbide (ZB-GeC) are investigated by the first-principles calculation. The results show that substitution of B, Ni in Ge sub-lattice site and N in C sub-lattice site are energetically more favorable. The band structures of B- and N-doped ZB-GeC show p- and n-type semiconductor characteristic, respectively. While for Ni-doped ZB-GeC, new dopant-induced energy levels emerge in the center of the band gap. Indirect to direct transition and gap shrink occur when the dopants are incorporated. Furthermore, Ni-doped ZB-GeC is found to be a paramagnetic material. The imaginary parts of dielectric functions reveal that the doping can improve the photo-absorption efficiency of ZB-GeC with new absorbing peaks emerge in the near-infrared region, visible region, and middle-ultraviolet region in the absorption spectrum. The conductivity spectra of doped ZB-GeC shows that the conductivity of ZB-GeC also gets improved. These features indicate that the doped ZB-GeC can be a promising optoelectronic material.