Photoelectrochemical Photodetector Based on Germanium Telluride Film Synthesized by Physical Vapor Deposition

Benefiting from the attractive high carrier mobility, large absorption coefficient, and ambient stability, group IV–VI compounds show excellent potential applications for optoelectronic devices. Herein, a germanium telluride (GeTe) film with a nanosphere structure has been controllably grown by facile physical vapor deposition and utilized into a photoelectrochemical (PEC)-type photodetector. The GeTe-based PEC-type photodetector possesses an excellent photoresponse and high responsivity in the visible region. Meanwhile, density functional theory calculations were employed to investigate the electronic characteristics of GeTe, supplying evidence of the broadband absorption. The improvement of photoelectric response can be attributed to the thicker films due to the larger light harvesting and higher carrier concentration, which is also verified by the visible–near-infrared absorption spectra and electrochemical impedance spectroscopy. The photocurrent density (Iph) and photoresponsivity (Rph) values of the GeTe-based photodetector can reach 22.8 μA/cm2 and 228.9 μA/W. Generally, our work provides an effective way to extend semiconductor materials in applications of PEC-type photodetectors.