Electronic structures and energy band properties of Be- and S-doped wurtzite ZnO

The energy band properties, density of states, and band alignment of the Be_xZn_1-xO_1-yS_y alloy (Be- and S-doped wurtzite ZnO) are investigated by the first-principles method. Be_xZn_1-xO_1-yS_y alloy is a direct band gap semiconductor, the valence band maximum (VBM) and the conduction band minimum (CBM) of Be_xZn_1-xO_1-yS_y are dominated by S 3p and Zn 4s states, respectively. The band gap and lattice constant of Be_xZn_1-xO_1-yS_y alloy can be modulated by changing the doped content values x and y. With the increase in Be content value x in the Be_xZn_1-xO_1-yS_y alloy, the band gap increases and the lattice constant reduces, but the situation is just the opposite when increasing the S content value y in the Be_xZn_1-xO_1-yS_y alloy. Because the lattice constant of Be_0.375Zn_0.625O_0.75S_0.25 alloy is well matched with that of ZnO and its energy gap is large compared with that of ZnO, so the Be_0.375Zn_0.625O_0.75S_0.25 alloy is suitable for serving as the blocking material for a high-quality ZnO-based device.