Walter Schottky Institut and Physics Department , Technical University Munich , Garching 85748 , Germany.
Nano Lett. 2019 Feb 13;19(2):990-996. doi: 10.1021/acs.nanolett.8b04226. Epub 2019 Jan 23.
Contactless time-resolved optical pump-probe and external quantum efficiency measurements were performed in epitaxially grown free-standing wurtzite indium arsenide/indium aluminum arsenide (InAs-InAlAs) core-shell nanowires on Si (111) substrate from 77 to 293 K. The first independent investigation of Shockley-Read-Hall, radiative, and Auger recombination in InAs-based NWs is presented. Although the Shockley-Read-Hall recombination coefficient was found to be at least 2 orders of magnitude larger than the average experimental values of other reported InAs materials, the Auger recombination coefficient was reported to be 10-fold smaller. The very low Auger and high radiative rates result in an estimated peak internal quantum efficiency of the core-shell nanowires as high as 22% at 77 K, making these nanowires of potential interest for high-efficiency mid-infrared emitters. A greater than 2-fold enhancement in minority carrier lifetime was observed from capping nanowires with a thin InAlAs shell due to the passivation of surface defects.
从 77 到 293 K，在 Si（111）衬底上外延生长的自由-standing 纤锌矿砷化铟/砷化铝铟（InAs-InAlAs）核壳纳米线中进行了无接触时间分辨光泵浦探测和外量子效率测量。首次对基于 InAs 的 NWs 中的 Shockley-Read-Hall、辐射和俄歇复合进行了独立研究。尽管 Shockley-Read-Hall 复合系数至少比其他报道的 InAs 材料的平均实验值大 2 个数量级，但俄歇复合系数却小了 10 倍。非常低的俄歇复合和高辐射速率导致在 77 K 时核壳纳米线的估计峰值内量子效率高达 22%，这使得这些纳米线成为高效中红外发射器的潜在关注点。通过用薄的 InAlAs 壳覆盖纳米线，可以观察到少子寿命提高了 2 倍以上，这是由于表面缺陷的钝化。
