Verma Sandeep Kumar, Sharma Sanjay, Maurya Gyanendra Kumar, Gautam Vidushi, Singh Roshani, Singh Ajeet, Kandpal Kavindra, Kumar Pramod, Kumar Arun, Wiemer Claudia
Spintronics and Magnetic Materials Laboratory, Indian Institute of Information Technology, Allahabad, UP, India, 211015.
Department of Physics, Veer Bahadur Singh Purvanchal University, Jaunpur, UP, India, 222003.
Phys Chem Chem Phys. 2023 Sep 20;25(36):25008-25017. doi: 10.1039/d3cp03610c.
Topological insulators have emerged as one of the most promising candidates for the fabrication of novel electronic and optoelectronic devices due to the unique properties of nontrivial Dirac cones on the surface and a narrow bandgap in the bulk. In this work, the SbTe and BiTeSe materials, and their heterostructure are fabricated by metal-organic chemical vapour deposition and evaporation techniques. Photodetection of these materials and their heterostructure shows that they detect light in a broadband range of 600 to 1100 nm with maximum photoresponse of SbTe, BiTeSe and SbTe/BiTeSe at 1100, 1000, and 1000 nm, respectively. The maximum responsivity values of SbTe, BiTeSe, and their heterostructure are 183, 341.8, and 245.9 A W at 1000 nm, respectively. A computational study has also been done using density functional theory (DFT). Using the first-principles methods based on DFT, we have systematically investigated these topological insulators and their heterostructure's electronic and optical properties. The band structures of SbTe and BiTeSe thin films (3 QL) and their heterostructure are calculated. The bandgaps of SbTe and BiTeSe are 26.4 and 23 meV, respectively, while the SbTe/BiTeSe heterostructure shows metallic behaviour. For the optical properties, the dielectric function's real and imaginary parts are calculated using DFT and random phase approximation (RPA). It is observed that these topological materials and their heterostructure are light absorbers in a broadband range, with maximum absorption at 1.90, 2.40, and 3.21 eV.
由于表面非平凡狄拉克锥的独特性质以及体相中较窄的带隙，拓扑绝缘体已成为制造新型电子和光电器件最有前景的候选材料之一。在这项工作中，通过金属有机化学气相沉积和蒸发技术制备了SbTe和BiTeSe材料及其异质结构。对这些材料及其异质结构的光探测表明，它们在600至1100nm的宽带范围内探测光，SbTe、BiTeSe和SbTe/BiTeSe的最大光响应分别在1100nm、1000nm和1000nm处。SbTe、BiTeSe及其异质结构在1000nm处的最大响应率值分别为183、341.8和245.9 A/W。还使用密度泛函理论（DFT）进行了一项计算研究。基于DFT的第一性原理方法，我们系统地研究了这些拓扑绝缘体及其异质结构的电子和光学性质。计算了SbTe和BiTeSe薄膜（3个量子层）及其异质结构的能带结构。SbTe和BiTeSe的带隙分别为26.4和23meV，而SbTe/BiTeSe异质结构表现出金属行为。对于光学性质，使用DFT和随机相位近似（RPA）计算了介电函数的实部和虚部。观察到这些拓扑材料及其异质结构在宽带范围内是光吸收体，在1.90、2.40和3.21eV处有最大吸收。
