Robust photogalvanic effect, full spin polarization and pure spin current in the BiC photodetector by vacancy- and substitution-doping.

The photogalvanic effects (PGEs) in low-dimensional devices have attracted great interests recently. Herein, based on non-equilibrium Green's function combined with density functional theory, we investigated spin-dependent PGE phenomena in the BiC photodetector for the case of linearly polarized light and zero bias. Due to the presence of strong spin-orbital interaction (SOI) and C3v symmetry for the BiC monolayer, the armchair and zigzag BiC photodetectors produce robust spin-dependent PGEs which possess the cos(2θ) and sin(2θ) relations on the photon energies. Especially, the armchair and Bi-vacancy armchair BiC photodetector can produce fully spin polarization, and pure spin current was found in the armchair and zigzag BiC photodetector. Furthermore, after introducing the Bi-vacancy, C-vacancy, Bi-doping and C-doping respectively, corresponding armchair and zigzag BiC photodetector can produce higher spin-dependent PGEs for their Cs symmetry. Moreover, the behaviors of spin-dependent photoresponse are highly anisotropic and can be tuned by the photon energy. This work suggested great potential applications of the BiC monolayer on PGE-driven photodetectors in low energy-consumption optoelectronics and spintronic devices. .