Electronic structures of Mg_3Pn_2 (Pn=N, P, As, Sb and Bi) and Ca_3N_2 calculated by a first-principle pseudopotential method

摘要

Electronic structure calculations for Mg_3N_2,Mg_3P_2, Mg_3As_2 (low and high temperature modifications), Mg_3Sb_2, Mg_3Bi_2, and Ca_3N_2 have been performed. Mg_3Sb_2 is predicted to be an indirect semiconductor with the gap value of about 0.41 eV. Mg_3As_2 with a high temperature modification is also predicted to be a semiconductor with the gap value of about 1.1 eV, but the valence band maximum and the conduction band minimum of Mg_3Bi_2 contacts at Γ which would make it a semimetal. Mg_3N_2, Mg_3P_2, and Mg_3As_2 (low temperature phase) are semiconductors with the direct band gaps of 1.64 eV, 1.73 eV, and 1.57 eV, respectively. Ca_3N_2 is a semiconductor with a gap of about 1.2 eV.