未钝化和H钝化GaN纳米线的电子结构

Electronic Structures of Unsaturated and H Saturated GaN Nanowires

用密度泛函理论研究直径为9.5,15.9和22.5,未钝化和H钝化GaN纳米线的能带和态密度.结果表明:未钝化和H钝化GaN纳米线的能隙都是直接带隙,未钝化GaN纳米线的禁带宽度随着直径的增加减小,但是变化不明显,H钝化GaN纳米线的禁带宽度随着直径增大也是减小的,但是减小的幅度比未钝化的大.未钝化GaN纳米线表面N原子的2p电子主要聚集在价带顶,表面Ga原子的4p电子主要聚集在导带底,这两种电子都具有很强的局域性,而且决定着能隙值;加H钝化可以消除表面原子产生的表面效应.

Electronic structures of unsaturated and H saturated GaN nanowires with diameters of 9.5 A, 15.9 A and 22.5 A are studied with generalized gradient approximation （GGA） of density functional theory （DFT）. Results show that unsaturated and H saturated GaN nanowires have direct band gaps. Band gaps of unsaturated GaN nanowires decrease with the increase of nanowire diameter, but not significantly. Band gaps of H saturated GaN nanowires decrease with the increase of nanowire diameter as well. They are more apparent than unsaturated ones. 2p electrons of N atoms in surface of unsaturated GaN nanowires locate at top of valence band, and 4p electrons of Ga atoms in surface locate at bottom of conduction band. These two kinds of electrons are local which decide the band gap. Surface effect of surface atoms can be eliminated by saturating with hydrogen atoms.