GaN/AlN量子点结构中的应变分布和压电效应

Strain Distribution and Piezoelectric Effect in GaN/AlN Quantum Dots

从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响.

An effective method is introduced to investigate the strained fields and piezoelectric effect in GaN/AIN quantum dots （QDs） with hexagonal truncated pyramid shape. The strain distribution and charge density were calculated using the finite element method （FEM）. It is shown that spontaneous and piezoelectric polarization resulted in the separation of electrons and holes, bringing about a strong built-in electric field in the QD structures. The strain field and piezoelectric potential influence the distribution of charges. The electrons are localized near the top of the QDs,and the holes are localized in the wetting layer just below the pyramid. Furthermore,the piezoelectric potential in the QDs affects the electron levels and band edge shape.