Thickness Dependence of Linearly Polarized Light-induced Mo-mentum Anisotropy and Inverse Spin Hall Effect in Topological Insulator Bi₂Te₃

The thickness dependence of the linearly polarized light induced momentum anisotropy and inverse spin Hall effect (PISHE) in the topological insulator (TI) Bi 2 Te 3 films has been investigated. A significant enhancement of the PISHE signal is observed in the 12-quintuple layer (QL) Bi 2 Te 3 film sample compared with that of the 3- and 5-QL samples, while a minimal value of photoinduced momentum anisotropy is observed in the 12-QL sample. The photoinduced momentum anisotropy and the PISHE in the Bi 2 Te 3 film are found to be more than three orders and two orders of mag-nitude larger than that in Bi 2 Se 3 film grown on SrTiO 3 substrate, respectively. The 3-QL sample exhibits a sinusoidal dependence of PISHE current on the light spot position, while the 5-QL and 12-QL samples show a W-shaped dependence, due to the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi 2 Te 3 films. Our findings demonstrate the critical role of film thickness in modulating both photoinduced momentum anisotropy and PISHE current, thereby proposing a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.