Energy band structure of Zn3P2-type semiconductors: Analysis of the crystal structure simplifications and energy band calculations

The simplifications of the Zn3P2-type crystal structure having tetragonal s ymmetry D-4h(15) have been analysed. After description of the real unit cel l the following simplifications are proposed: tetragonal symmetry (ideal an d D-4h(17)), cubic symmetry and the correct molecular ratio (approximations O-h(9), T-h(7) and O-h(4)) and finally the zincblende and antifluorite app roximations. In the second part we present the results of energy band calcu lations for fully symmetric Zn3P2, and for all the simplifications. The sym metry of bands is also determined for the full crystal structure and for th e ideal approximation. In the calculations the nonlocal empirical pseudopot ential method has been used.