Polarization-dependent photocurrent in a quadrilateral-shaped bulk crystalline tellurium chip with near-infrared light excitation

Abstract

We report the detection of zero-bias photocurrents induced by interband excitation using oblique near-infrared light ({\lambda}=0.780 {\mu}m) along the directions parallel and perpendicular to the helical axis in a millimeter-sized Te crystal. The photocurrent parallel to the helical axis exhibits a circular-polarization-dependent component, namely circular photogalvanic effect. We create a framework for estimating the gyrotropic photoconductivity tensor \b{eta}, the ratio between the circular-polarization-dependent photocurrent density and intensity of light, through which extrinsic \b{eta} values ranging from a few to a few tens of nA/W are obtained. Searching the \b{eta} values through existing literatures reveals that these values vary significantly with sample conditions, excitation wavelengths, and forms of crystallite samples. A particular interesting point found in our study is that the \b{eta} values for the interband excitation may be greater than those for intraband excitation as far as bulk Te is concerned.