Wei Chengrong, Chen Xi, Li Dian, Su Huimin, He Hongtao, Dai Jun-Feng
Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China.
Physics Department, The University of Hong Kong, Pokfulam road, Hong Kong, China.
Sci Rep. 2016 Sep 22;6:33890. doi: 10.1038/srep33890.
The photoluminescence (PL) and absorption experiments have been performed in GaSe slab with incident light polarized perpendicular to c-axis of sample at 10 K. An obvious energy difference of about 34 meV between exciton absorption peak and PL peak (the highest energy peak) is observed. By studying the temperature dependence of PL and absorption spectra, we attribute it to energy difference between free exciton and bound exciton states, where main exciton absorption peak comes from free exciton absorption, and PL peak is attributed to recombination of bound exciton at 10 K. This strong bound exciton effect is stable up to 50 K. Moreover, the temperature dependence of integrated PL intensity and PL lifetime reveals that a non-radiative process, with activation energy extracted as 0.5 meV, dominates PL emission.
在10K温度下，对GaSe薄片进行了光致发光（PL）和吸收实验，入射光偏振方向垂直于样品的c轴。观察到激子吸收峰与PL峰（最高能量峰）之间存在约34meV的明显能量差。通过研究PL光谱和吸收光谱的温度依赖性，我们将其归因于自由激子和束缚激子态之间的能量差，其中主要激子吸收峰来自自由激子吸收，而PL峰归因于10K时束缚激子的复合。这种强束缚激子效应在高达50K时都是稳定的。此外，积分PL强度和PL寿命的温度依赖性表明，一个激活能为0.5meV的非辐射过程主导了PL发射。
