First-principles study on effective doping in IVA group spinel nitrides

Hao Wang

Authors: Hao Wang¹, Ying Chen¹, Yasunori Kaneta¹, Shuichi Iwata²

¹Dept. of Quantum Eng. and Systems Sci., The University of Tokyo

²Graduate School of Frontier Sciences, The University of Tokyo

The spinel materials have attracted interesting as a new family with wide and direct electronic band gap. IVA group elements form a fulfill spinel family, but a lot of them can not be stabilized at ambient condition. In present research we investigate the electronic and optical properties, as well the structural stability of IVA spinel materials, in order to find appropriate base substances from which further doping technology is employed aiming at improving their optical properties.

FLAPW approach with PBE-GGA exchange and correlation potential has been utilized to investigate the structural and electronic properties. The random phase approximation is applied to calculate the optical property such as dielectric function

The ground state properties of a group of spinel and double spinel compounds A_3-xB_xN₄ (x=0,1,2,3, A and B are IV group element C, Si, Ge, Sn) have been performed by FLAPW. By examining the formation energies with considering other properties such as the energy gap, dielectric function, we found SiGe₂N₄ is a best candidate substance. Doping elements are selected based on a detailed analysis on the imaginary part of the dielectric function to identify the large inter-band transitions. Our calculation shows that implanting As into particular sites of unit cell significantly raises the peak of imaginary part of dielectric function.