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本文利用第一性原理对类石墨烯GaN和WS_2/WSe_2构成的复合材料的结构,电学及光学性质进行了系统的研究.氮化镓和WS_2/WSe_2之间通过范德华力进行相互作用,且这两种纳米复合结构中最稳定的构型都显示出直接带隙的特征.同时,由于导带底和价带顶分别由WS_2(或WS e2)和GaN贡献,这两种复合结构形成了第二类异质结.我们对这两种异质结构的介电函数虚部和吸收光谱进行了计算并观察到由带间跃迁所引起的光学性质的增强.此外,能带偏移以及由电荷转移所产生的内建电场能够有效地抑制电荷-空穴对的复合,这对于光催化过程十分有利.通过施加双轴应变能有效地调节这两个异质结的带隙,甚至能在一定程度上使导带边远离H~+/H_2势能,从而进一步地提升异质结构的光催化性能.研究结果表明GaN/WS_2和GaN/WSe_2是优异的光催化和光电应用的候选材料.
In this paper, the structural, electrical and optical properties of graphene-like graphene (GaN) and WS_2 / WSe_2 composites have been studied systematically using the first-principles theory. The interactions between GaN and WS_2 / WSe_2 are based on van der Waals forces, Both of the most stable configurations of the two nanocomposite structures show the direct bandgap characteristics. At the same time, due to the contributions of WS_2 (or WSe2) and GaN at the conduction band bottom and valence band top, the two composite structures form the The second type of heterojunction. We calculated the imaginary part and absorption spectra of the dielectric functions of the two heterostructures and observed the enhancement of the optical properties caused by the interband transition. In addition, the band offset, The built-in electric field generated by the transfer can effectively suppress the recombination of charge-hole pairs, which is very advantageous for the photocatalytic process. The band gap of these two heterojunctions can be effectively adjusted by applying biaxial strain, The results show that GaN / WS 2 and GaN / WSe 2 are excellent candidates for photocatalytic and optoelectronic applications.