Deitz Julia I, Sarwar A T M Golam, Carnevale Santino D, Grassman Tyler J, Myers Roberto C, McComb David W
1Department of Materials Science and Engineering,The Ohio State University,Columbus,OH 43210,USA.
2Department of Electrical and Computer Engineering,The Ohio State University,Columbus,OH 43210,USA.
Microsc Microanal. 2018 Apr;24(2):93-98. doi: 10.1017/S143192761800017X.
The ability to characterize recombination and carrier trapping processes in group-III nitride-based nanowires is vital to further improvements in their overall efficiencies. While advances in scanning transmission electron microscope (STEM)-based cathodoluminescence (CL) have offered some insight into nanowire behavior, inconsistencies in nanowire emission along with CL detector limitations have resulted in the incomplete understanding in nanowire emission processes. Here, two nanowire heterostructures were explored with STEM-CL: a polarization-graded AlGaN nanowire light-emitting diode (LED) with a GaN quantum disk and a polarization-graded AlGaN nanowire with three different InGaN quantum disks. Most nanowires explored in this study did not emit. For the wires that did emit in both structures, they exhibited asymmetrical emission consistent with the polarization-induced electric fields in the barrier regions of the nano-LEDs. In the AlGaN/InGaN sample, two of the quantum disks exhibited no emission potentially due to the three-dimensional landscape of the sample or due to limitations in the CL detection.
表征基于III族氮化物的纳米线中的复合和载流子俘获过程的能力对于进一步提高其整体效率至关重要。虽然基于扫描透射电子显微镜（STEM）的阴极发光（CL）技术的进步为纳米线行为提供了一些见解，但纳米线发射的不一致以及CL探测器的局限性导致对纳米线发射过程的理解不完整。在此，利用STEM-CL研究了两种纳米线异质结构：一种具有GaN量子盘的极化渐变AlGaN纳米线发光二极管（LED）和一种具有三个不同InGaN量子盘的极化渐变AlGaN纳米线。本研究中探索的大多数纳米线不发光。对于在两种结构中都发光的纳米线，它们表现出与纳米LED势垒区域中极化诱导电场一致的不对称发射。在AlGaN/InGaN样品中，其中两个量子盘没有发射，这可能是由于样品的三维形貌或CL检测的局限性所致。
