Topological Insulator TlBiSe₂/GaN Vertical Heterojunction Diode for High Responsive Broadband UV to Near-Infrared Photodetector

Quasi-2D thin film of TI material TlBiSe₂, as well as TlBiSe2/GaN configuration, have been fabricated employing the thermal evaporation technique. Raman peaks of vibrational modes were analyzed in a TlBiSe₂/GaN heterojunction showing a substrate-induced signal for the surface phonon mode (SPM). The study of ultrafast kinetics of charge carriers and transient absorption spectroscopy (TAS) gave excited-state spectrum characteristics and exciton dynamics in TlBiSe₂/GaN heterojunction. The electrical characterization showed that the heterojunction device exhibited a good diode nature with an excellent rectification ratio of 160. The photodetection capabilities were examined by optical power varying from 2.37 µW to 3.78 µW in the ultraviolet to near-infrared region (300–900 nm). It demonstrated maximum photoresponse at 500 nm in forward and reverse bias. The current conduction mechanism and enhancement in current under light impact were explained using energy band modeling. The present work is important in regarding the development of photodetectors of succeeding generations with a topological insulator material.