Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049, Madrid, Spain.
Nanotechnology. 2019 Jun 14;30(24):24LT01. doi: 10.1088/1361-6528/ab0bc1. Epub 2019 Mar 1.
Few-layer GaSe is one of the latest additions to the family of two-dimensional semiconducting crystals whose properties under strain are still relatively unexplored. Here, we study rippled nanosheets that exhibit a periodic compressive and tensile strain of up to 5%. The strain profile modifies the local optoelectronic properties of the alternating compressive and tensile regions, which translates into a remarkable shift of the optical absorption band-edge of up to 1.2 eV between crests and valleys. Our experimental observations are supported by theoretical results from density functional theory calculations performed for monolayers and multilayers (up to seven layers) under tensile and compressive strain. This large band gap tunability can be explained through a combined analysis of the elastic response of Ga atoms to strain and the symmetry of the wave functions.
少层 GaSe 是二维半导体晶体家族中的最新成员之一，其在应变下的性质仍相对未知。在这里，我们研究了波纹纳米片，其表现出高达 5%的周期性压缩和拉伸应变。应变分布改变了交替压缩和拉伸区域的局部光电特性，这导致在峰谷之间光学吸收带边的显著移动高达 1.2eV。我们的实验观察结果得到了密度泛函理论计算的支持，这些计算针对拉伸和压缩应变下的单层和多层（最多七层）进行了计算。这种大的带隙可调谐性可以通过对 Ga 原子对应变的弹性响应和波函数的对称性的综合分析来解释。
