▎ 摘　　要

Based on the first-principles calculation method of quantum mechanics, we systematically studied the geometric structure and electronic properties of graphene/CdSe heterojunction, and considered the influence of vertical strain on its performance. The calculated results show that the model II has the smallest binding energy of-1.09 eV when the interlayer distance is 3.4 angstrom. Graphene opens a small band gap of 3 meV, which indicates that it has a good application prospect in future micro-nano devices. Differential charge density found that the electrons and holes at the interface gathered on the surface of CdSe and graphene, respectively. When the interlayer distance increases from 2.6 angstrom to 4.0 angstrom, the band gap decreases from 19 meV to 1 meV. In addition, the most stable heterojunction has n-and p-type Schottky barrier heights of 0.224 eV and 1.324 eV, respectively, thus the system forms n-type Schottky contact. As the interlayer distance increases, the n- and p-type Schottky barrier heights continuously decrease and increase, respectively. When the interlayer distance increases from 2.6 angstrom to 2.8 angstrom, the heterojunction changes from p-type Schottky contact to n-type Schottky contact, and when the interlayer dis-tance reaches 4.2 angstrom, the heterojunction can realize the transformation from n-type Schottky contact to n-type Ohmic contact. These findings may have potential guiding significance for the design and preparation of gra-phene/CdSe heterojunction nanodevices.