Chen Jiyang, Bhattarai Romakanta, Cui Jingbiao, Shen Xiao, Hoang Thang
Department of Physics and Materials Science, University of Memphis, Memphis, TN, 38152, USA.
Department of Physics, The University of North Texas, Denton, TX76203, USA.
Sci Rep. 2020 Nov 5;10(1):19205. doi: 10.1038/s41598-020-76265-1.
We report a combined experimental and computational study of the optical properties of individual silicon telluride (SiTe) nanoplates. The p-type semiconductor SiTe has a unique layered crystal structure with hexagonal closed-packed Te sublattices and Si-Si dimers occupying octahedral intercalation sites. The orientation of the silicon dimers leads to unique optical and electronic properties. Two-dimensional SiTe nanoplates with thicknesses of hundreds of nanometers and lateral sizes of tens of micrometers are synthesized by a chemical vapor deposition technique. At temperatures below 150 K, the SiTe nanoplates exhibit a direct band structure with a band gap energy of 2.394 eV at 7 K and an estimated free exciton binding energy of 150 meV. Polarized reflection measurements at different temperatures show anisotropy in the absorption coefficient due to an anisotropic orientation of the silicon dimers, which is in excellent agreement with theoretical calculations of the dielectric functions. Polarized Raman measurements of single SiTe nanoplates at different temperatures reveal various vibrational modes, which agree with density functional perturbation theory calculations. The unique structural and optical properties of nanostructured SiTe hold great potential applications in optoelectronics and chemical sensing.
我们报告了一项关于单个碲化硅（SiTe）纳米片光学性质的实验与计算相结合的研究。p型半导体SiTe具有独特的层状晶体结构，其中六方密堆积的Te亚晶格和占据八面体嵌入位点的Si - Si二聚体。硅二聚体的取向导致了独特的光学和电子性质。通过化学气相沉积技术合成了厚度为数百纳米、横向尺寸为数十微米的二维SiTe纳米片。在低于150 K的温度下，SiTe纳米片呈现出直接带隙结构，在7 K时带隙能量为2.394 eV，估计自由激子结合能为150 meV。不同温度下的偏振反射测量表明，由于硅二聚体的各向异性取向，吸收系数存在各向异性，这与介电函数的理论计算结果非常吻合。在不同温度下对单个SiTe纳米片进行的偏振拉曼测量揭示了各种振动模式，这与密度泛函微扰理论计算结果一致。纳米结构SiTe独特的结构和光学性质在光电子学和化学传感方面具有巨大的潜在应用价值。
