Vacancy-induced giant photogalvanic effect in TiSe2 heterojunctions

We adopt nonequilibrium Green's functions and density functional theory to study the effect of Se atom defects on the transport properties and the photocurrent of a $1T\ensuremath{-}{\mathrm{TiSe}}_{2}$ heterojunction. We calculate the photocurrent for two types of defect configurations under the excitation of the linearly polarized light. The results show that Se1 and Se2 vacancy defects can induce large photocurrents, which are explained in terms of the transmission spectrum. The photocurrent shows anisotropic behaviors for different illuminated directions. Meanwhile, the extinction ratio reflecting the polarization sensitivity can reach a maximum value of 445.12. The photoresponsivities of the device with vacancy defects can have relatively large values in certain energy ranges. The $1T\ensuremath{-}{\mathrm{TiSe}}_{2}$-based device is a promising candidate for anisotropic light detection.