Applied Quantum Mechanics Laboratory, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India.
Nanotechnology. 2019 May 10;30(19):194003. doi: 10.1088/1361-6528/ab0035. Epub 2019 Feb 25.
Understanding the ultrafast processes corresponding to carrier capture, thermalization and relaxation is essential to design high speed optoelectronic devices. Here, we have investigated a size dependent carrier capture process in InGaN/GaN 20, 50 nm nanowires and quantum well systems. Femto-second transient absorption spectroscopy reveals that the carrier capture is a two-step process. The carriers are captured in the barrier by polar optical phonon (POP) scattering. They further scatter into the active region by electron-electron and POP scatterings. The capture is found to slow down for quantum confined structures. A significant number of carriers are found to disappear from the barrier during the diffusion process. All the experimental observations are explained in a simulation framework depicting various scattering mechanisms.
了解与载流子俘获、热化和弛豫相对应的超快过程对于设计高速光电设备至关重要。在这里，我们研究了 InGaN/GaN 20nm、50nm 纳米线和量子阱系统中尺寸相关的载流子俘获过程。飞秒瞬态吸收光谱表明，载流子俘获是一个两步过程。载流子通过极性光学声子（POP）散射被捕获在势垒中。它们通过电子-电子和 POP 散射进一步散射到有源区。发现对于量子限制结构，俘获过程会减慢。在扩散过程中，大量载流子被发现从势垒中消失。所有的实验观察结果都在一个模拟框架中得到了解释，该框架描述了各种散射机制。
