Cr掺杂浓度对AlN半金属性影响的第一性原理研究

Concentration's effect on the half-metallic properties of Cr doped AlN:first principles study

本文基于密度泛函理论的第一性原理方法,在广义梯度近似(GGA)下计算了掺杂过渡金属Cr原子后AlN晶体自旋极化的能带结构、分态密度等性质.结果表明,半金属能隙随着掺杂浓度的增大而减小.文中以掺杂浓度为12.5%的Cr—A1N(2×2×1)为例,分析了其自旋极化的能带结构、分态密度和磁矩等性质,发现Cr—3d电子对自旋向下子带导带底的能量位置起决定作用.随着掺杂浓度的增大,Cr原子间相互作用增强,Cr—3d能带向两边展宽,导致自旋向下子带导带底的能量位置下降,从而半金属能隙变窄.

The half-metallic properties of transition metal Cr doped wurtzite AlN crystal were studied by density-functional theory using the generalized gradient approximation （GGA） for the exchange-correlation potential. The result indicates that the half-metallic gap decreases with increasing Cr doped concentrations. Analysis of the spin-polarized band structures, partial density of states （PDOS） and the molecular moment of Cr--AIN （2 × 2 × 1） shows that the conduction band minimum of down-spin bands is determined by Cr--3d states. The interaction between Cr atoms enhances and Cr--3d bands broaden with increasing Cr doped concentrations, which results in the decrease of the conduction band minimum of down-spin bands, so the half-metallic gap reduces.