Photogalvanic Effect In Chromium-Doped Monolayer Mos2 From First Principles

Non-equilibrium green's function fromalism combined with density functional theory is used to investigate the photogalvanic effect of chromium (Cr)-doped monolayer molybdenum disulfide (MoS2) from first principles. Since the Cr-doped monolayer MoS2 belongs to the C(2)v point group which is non-inversion symmetric, the photocurrent can be generated at zero bias when irradiated by linearly or circularly polarized light. Then, the photoresponse for the circular photogalvanic effect (CPGE) and linear photogalvanic effect (LPGE) at different photon energies are investigated. It is found that the photoresponse of the CPGE is one order of magnitude larger than the LPGE and there are peaks around 1.5 eV, 1.9 eV and 2.0 eV for the CPGE. Especially, the photocurrent reaches the maximum value at the photon energy of 1.5 eV (red light) for the CPGE. These results can be explained by the electron transition between valence bands and conduction bands, which is proportional to density of states according to the Fermi's golden rule. Furthermore, we investigate the dependence of the photocurrent on polarization angle theta and phi for the LPGE and CPGE. Since the Cr-doped monolayer MoS2 can generate a large photocurrent in the visible light range, it can be used as an excellent photogalvanic material. This work indicates that Cr-doped monolayer MoS2 can provide some theoretical references for the research and design of novel electronic or optoelectronic devices.