窄带隙超晶格中载流子俄歇寿命和碰撞电离率的第一性原理研究

通过第一性原理的完整形式,基于全势能线性化增广平面波方法确定的精确能带结构和波函数,推算了技术上极为重要的窄带隙半导体超晶格中载流子俄歇复合时间.少数载流子的俄歇寿命由两种相关的方法来确定:1)由Fermi-金规则直接估算,2)联系俄歇复合和其相反过程碰撞电离,建立细致平衡公式,在一个统一的结构中进行间接估算.在n掺杂HgTe/CdTe和InAs/In_xGa_1－xSb超晶格中,由直接和间接的方法确定的寿命与一些实验结果相当一致.这说明该计算模式可以作为一种精确的手段用于窄带隙超晶格材料的性能优化. 关键词： 第一性原理 俄歇复合 碰撞电离 半导体超晶格

First-principles investigation of carrier Auger lifetime and impact ionization rate in narrow-gap superlattices

We investigate theoretically the technologically essential Auger recombination lifetime in narrow-gap semiconductor superlattices by means of a completely first-principles formalism, based on accurate energy bands and wave functions provided by the full-potential linearized augmented plane wave scheme. The minority carrier Auger lifetimes are determined by two correlated approaches: (1) direct evaluation in Fermi's golden rule, and (2) indirect evaluation, based on a detailed balance formulation relating Auger recombination and its inverse process, impact ionization, in a unified framework. Lifetimes determined by the direct and indirect methods for n -doped HgTe/CdTe and InAs/In_xGa_1-xSb superlattices exhibit excellent consistency with experimentally measured values. This justifies the computational formalism as a new sensitive tool in performance optimization of the synthetic narrow-gap semiconductor superlattice systems.