Udai Ankit, Ganguly Swaroop, Bhattacharya Pallab, Saha Dipankar
Applied Quantum Mechanics Laboratory, Indian Institute of Technology; Bombay, Powai, Mumbai-400076, India.
Solid-State Electronics Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, 48109-2122, United States of America.
Nanotechnology. 2022 Sep 5;33(47). doi: 10.1088/1361-6528/ac8a50.
This work employs femtosecond transient absorption spectroscopy to investigate the ultrafast carrier dynamics of bound states in InGaN/GaN quantum wells. The ground state (GS) dynamics usually dominate these characteristics, appearing as a prominent peak in the absorption spectra. It is observed that the excited state also contributes to the overall dynamics, with its signature showing up later. The contributions of both the ground and excited states in the absorption spectra and time-resolved dynamics are decoupled in this work. The carrier density in the GS first increases and then decays with time. The carriers populate the excited state only at a delayed time. The dynamics are studied considering the Quantum-Confined Stark Effect-induced wavelength shift in the absorption. The relevant microscopic optoelectronic processes are understood phenomenologically, and their time constants are extracted. An accurate study of these dynamics provides fundamentally essential insights into the time-resolved dynamics in quantum-confined heterostructures and can facilitate the development of efficient light sources using GaN heterostructures.
这项工作采用飞秒瞬态吸收光谱来研究InGaN/GaN量子阱中束缚态的超快载流子动力学。基态（GS）动力学通常主导这些特性，表现为吸收光谱中的一个突出峰值。据观察，激发态也对整体动力学有贡献，其特征稍后出现。在这项工作中，吸收光谱和时间分辨动力学中基态和激发态的贡献被解耦。GS中的载流子密度首先随时间增加然后衰减。载流子仅在延迟时间填充到激发态。考虑到吸收中量子限制斯塔克效应引起的波长移动来研究动力学。从现象学上理解相关的微观光电过程，并提取它们的时间常数。对这些动力学的精确研究为量子限制异质结构中的时间分辨动力学提供了根本性的重要见解，并有助于使用GaN异质结构开发高效光源。
