Long-lived excitons in GaN/AlN nanowire heterostructures
Long-lived excitons in GaN/AlN nanowire heterostructures
复制标题
DOI：
10.1103/physrevb.91.205440
复制
发表时间：
2014-12
影响因子：
3.7
通讯作者：
M. Beeler;C. Lim;P. Hille;Joël Bleuse;J. Schormann;M. Mata;J. Arbiol;M. Eickhoff;E. Monroy
中科院分区：
文献类型：
--
作者：
M. Beeler;C. Lim;P. Hille;Joël Bleuse;J. Schormann;M. Mata;J. Arbiol;M. Eickhoff;E. Monroy
GaN/AlN纳米线异质结构可以显示持续到室温的微秒量级的光致发光（PL）衰减时间。用Ge掺杂GaN纳米盘插入物可以将这些PL衰减时间减少两个数量级。这些现象解释的三维电场分布内的GaN纳米盘，它具有在几MV/cm的范围内的自发和压电极化的轴向分量，和径向压电贡献相关联的晶格应变的剪切分量。在低掺杂剂浓度下，在轴向和径向方向上都存在大的电子-空穴分离。相对较弱的径向电场，这是约一个数量级小于轴向场，被掺杂迅速屏蔽。这种双向屏蔽导致电子下方空穴的径向和轴向集中，因此，除了发光蓝移之外，PL衰减时间大幅减少。
GaN/AlN nanowire heterostructures can display photoluminescence (PL) decay times on the order of microseconds that persist up to room temperature. Doping the GaN nanodisk insertions with Ge can reduce these PL decay times by two orders of magnitude. These phenomena are explained by the three-dimensional electric field distribution within the GaN nanodisks, which has an axial component in the range of a few MV/cm associated to the spontaneous and piezoelectric polarization, and a radial piezoelectric contribution associated to the shear components of the lattice strain. At low dopant concentrations, a large electron-hole separation in both the axial and radial directions is present. The relatively weak radial electric fields, which are about one order of magnitude smaller than the axial fields, are rapidly screened by doping. This bidirectional screening leads to a radial and axial centralization of the hole underneath the electron, and consequently, to large decreases in PL decay times, in addition to luminescence blue shifts.