Circular photogalvanic effect of surface states in the topological insulator Bi2(Te0.23Se0.77)3nanowires grown by chemical vapor deposition

Abstract

Circular photogalvanic effect (CPGE) of single-crystalline ternary topological insulator Bi 2 (Te 0.23 Se 0.77) 3 nanowires, which are synthesized by the chemical vapor deposition, have been investigated. It is demonstrated that the distributions of the elements in the nanowires are fairly uniform, and they have high crystal quality. Compared with Bi 2 Se 3 nanowires, the ternary Bi 2 (Te 0.23 Se 0.77) 3 nanowires have better responsivity to circularly polarized light. The incident angle dependence of the CPGE current indicates that the symmetry of the surface states of the nanowire belongs to C 3 v symmetry. The temperature dependence of the CPGE current is also investigated. As the temperature decreases from 300 to 77 K, the CPGE current first increases and then decreases, which is due to the variation of the mobility and photo-generated carrier density with temperature. Our work suggests that ternary Bi 2 (Te 1 - x Se x) 3 nanowires are good candidates for designing polarization-sensitive photoelectric devices.