Thickness dependence of linearly polarized light-induced momentum anisotropy and inverse spin Hall effect in topological insulator Bi₂Te₃

The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect (PISHE) in topological insulator (TI) Bi₂Te₃ films has been investigated. A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer (QL) Bi₂Te₃ film compared with that of the 3- and 5-QL samples, whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample. The photoinduced momentum anisotropy and the PISHE in Bi₂Te₃ films are more than three and two orders of magnitude larger than those in Bi₂Se₃ films grown on SrTiO₃ substrates, respectively. The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position, while the 5-QL and 12-QL samples show a W-shaped dependence, which arises from the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi₂Te₃ films. Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current, thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.