单层 WSe₂ 中低温下局部缺陷态的长非指数 PL 衰减
Long lived localized defect states in monolayer WSe$_2$: Optical Lifetime distribution and thermal evolution
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中文总结 AI 辅助
研究单层 WSe₂ 中局部缺陷发射复合动力学，用时间分辨光致发光，在 4 至 120K 测量。缺陷发射含指数和幂律通道，通过温度相关测量等研究热脱陷阱机制，计算提供微观见解，为理解二维半导体长寿命非指数缺陷复合提供框架。
中文摘要 AI 辅助
我们利用时间分辨光致发光研究了单层 WSe₂ 中局部缺陷发射的复合动力学，温度范围为 4 至 120K。缺陷发射包括一个占主导的亚纳秒指数成分和两个从几纳秒到几百纳秒的弱长寿命幂律通道。幂律弛豫可根据与局部态非均匀集合相关的复合寿命连续分布来解释。进行了温度相关测量以研究控制这些长寿命通道的热脱陷阱机制。自旋分辨电子结构和光学跃迁计算提供了对局部态和可用复合途径的微观见解。这些结果为理解二维半导体中的长寿命非指数缺陷复合提供了框架。
英文摘要
We carefully investigate the recombination dynamics of localized defect emission in monolayer WSe$_2$ on SiO$_2$/Si substrate using time-resolved photoluminescence over the temperature range of 4 K to 120 K. We observe two long-lived optical lifetimes, one few nanosecond and one hundreds of nanoseconds. PL decay profile of these long lived states is fit well by a power-law, and based on laser fluence studies, the likely origin of the power-law is due to a distribution of life-times rather than many body interactions. Temperature-dependence of these rates shows that thermal detrapping governs these long-lived channels and we obtained a value of 60 meV for the characteristics energy in a Bose-Einstein model. We performed spin-resolved density functional calculations for selenium vacancies, the most likely source of native defects, to elucidate on spin- and momentum-forbidden pathways which are the likely origin of these long lifetimes. Such detailed understanding of long-lived defect states is crucial for quantum and optoelectronic applications.
