Institut d'Electronique Fondamentale UMR CNRS 8622, University Paris Sud, 91405 Orsay, France.
Nanotechnology. 2012 Aug 17;23(32):325701. doi: 10.1088/0957-4484/23/32/325701. Epub 2012 Jul 17.
The optical polarization properties of GaN/AlGaN core/shell nanowire (NW) heterostructures have been investigated using polarization resolved micro-photoluminescence (μ-PL) and interpreted in terms of a strain-dependent 6 × 6 k·p theoretical model. The NW heterostructures were fabricated in two steps: the Si-doped n-type c-axis GaN NW cores were grown by molecular beam epitaxy (MBE) and then epitaxially overgrown using halide vapor phase epitaxy (HVPE) to form Mg-doped AlGaN shells. The emission of the uncoated strain-free GaN NW core is found to be polarized perpendicular to the c-axis, while the GaN core compressively strained by the AlGaN shell exhibits a polarization parallel to the NW c-axis. The luminescence of the AlGaN shell is weakly polarized perpendicular to the c-axis due to the tensile axial strain in the shell.
我们利用偏振分辨微光致发光（μ-PL）研究了 GaN/AlGaN 核/壳纳米线（NW）异质结构的光学偏振特性，并根据应变相关的 6×6 k·p 理论模型对其进行了解释。该 NW 异质结构分两步制备：首先通过分子束外延（MBE）生长掺 Si 的 n 型 c 轴 GaN NW 核，然后使用卤化物气相外延（HVPE）外延生长 Mg 掺杂的 AlGaN 壳。未镀膜的无应变 GaN NW 核的发射是沿 c 轴偏振的，而被 AlGaN 壳压缩应变的 GaN 核则表现出沿 NW c 轴的平行偏振。由于壳中的拉伸轴向应变，AlGaN 壳的发光沿 c 轴呈弱的垂直偏振。
