Tunable electronic and optical properties of AlSb/InSe heterojunction and As and Te doped AlSb/InSe heterojunction based on first principles

The geometric properties of undoped AlSb/InSe van der Waals Heterojunction (vdWH) and As and Te doped AlSb/InSe vdWH are computed via Density Functional Theory (DFT). The three most stabilized heterojunctions are obtained: H1(undoped AlSb/InSe heterojunction with layer spacing of 2.81 Å), A1 (As-doped AlSb/InSe heterojunction with layer spacing of 2.92 Å) and B1 (Te doped AlSb/InSe heterojunction with layer spacing of 2.82 Å). By computing the electronic properties of the vdWH, it is concluded that H1, A1 and B1 AlSb/InSe vdWH are Type-Ⅱ band alignment (staggered gap) heterojunctions, and form Z-scheme electron transfer mechanism. The band gaps of H1, A1 and B1 heterojunction are 0.57 eV, 0.40 eV and 0.54 eV respectively. The band gap of A1 and B1 heterojunctions is smaller than that of H1, which resulted in higher photocatalytic activity. Via applying electrical field and stress to the three heterojunctions, it is found that not only the band size of heterojunction changes, but also the band arrangement type changes to Type-Ⅰ. Finally, by studying the optical properties of the heterojunction, it is found that the structure of the heterojunction can enhance the optical absorption coefficient.The applied stress and electric field can adjust the optical properties.