Varghese Sinto, Wang Sicheng, Neupane Bimal, Bhandari Bhojraj, Jiang Yan, Gonzalez Rodriguez Roberto, Krylyuk Sergiy, Davydov Albert V, Yan Hao, Wang Yuanxi, Kaul Anupama B, Cui Jingbiao, Lin Yuankun
Department of Physics, University of North Texas, Denton, Texas 76203, United States.
Department of Chemistry, University of North Texas, Denton, Texas 76203, United States.
ACS Omega. 2025 Feb 14;10(7):7466-7473. doi: 10.1021/acsomega.5c00680. eCollection 2025 Feb 25.
In this work, we report on defect generation in multilayer GaSe through hydrostatic pressure quenching and UV laser irradiation. The Raman line width from the UV 266 nm irradiated sample is much wider than that in pressure-quenched GaSe, corresponding to a wider defect energy distribution range in the former sample than the latter. After quenching from 11.2 GPa, three photoluminescence (PL) peaks from defect states are observed at 657, 681, and 695 nm at a low temperature of 93 K. Defect-related peaks at 649, 694, 750, and 774 nm also appear in low-temperature PL spectra after UV laser irradiation, with a nonmonotonous intensity dependence on irradiation duration. There are common features in defects produced by these two methods: the PL peaks with the lowest energy are sharp, and their PL intensities increase linearly with the excitation laser power and saturate above a certain excitation laser power. These two features are similar to those in defects for single-photon emission (SPE) in other 2D materials at even lower temperatures. Fluorescence lifetime imaging shows distinguished short (2.3 ns) and long (75.6 nm) lifetimes of the 695 nm PL line in pressure-quenched GaSe. The density functional theory predicts defect energy levels related to Se vacancy.
在这项工作中，我们报道了通过静水压力猝灭和紫外激光辐照在多层GaSe中产生缺陷的情况。紫外266 nm辐照样品的拉曼线宽比压力猝灭的GaSe中的拉曼线宽宽得多，这对应于前一个样品中的缺陷能量分布范围比后一个样品更宽。从11.2 GPa猝灭后，在93 K的低温下观察到来自缺陷态的三个光致发光（PL）峰，分别位于657、681和695 nm处。紫外激光辐照后的低温PL光谱中也出现了位于649、694、750和774 nm处的与缺陷相关的峰，其强度对辐照持续时间呈现非单调依赖性。这两种方法产生的缺陷具有共同特征：能量最低的PL峰很尖锐，并且它们的PL强度随激发激光功率呈线性增加，并在一定的激发激光功率以上达到饱和。这两个特征与其他二维材料在更低温度下单光子发射（SPE）缺陷中的特征相似。荧光寿命成像显示，压力猝灭的GaSe中695 nm PL线具有明显不同的短（2.3 ns）和长（75.6 ns）寿命。密度泛函理论预测了与硒空位相关的缺陷能级。
