Fast, Self-Driven, Air-Stable, and Broadband Photodetector Based on Vertically Aligned PtSe2/GaAs Heterojunction

Group-10 layered transitional metal dichalcogenides including PtS2, PtSe2, and PtTe2 are excellent potential candidates for optoelectronic devices due to their unique properties such as high carrier mobility, tunable bandgap, stability, and flexibility. Large-area platinum diselenide (PtSe2) with semiconducting characteristics is far scarcely investigated. Here, the development of a high-performance photodetector based on vertically aligned PtSe2-GaAs heterojunction which exhibits a broadband sensitivity from deep ultraviolet to near-infrared light, with peak sensitivity from 650 to 810 nm, is reported. The I-light/I-dark ratio and responsivity of photodetector are 3 x 10(4) and 262 mA W-1 measured at 808 nm under zero bias voltage. The response speed of tau(r)/tau(f) is 5.5/6.5 mu s, which represents the best result achieved for Group-10 TMDs based optoelectronic device thus far. According to first-principle density functional theory, the broad photoresponse ranging from visible to near-infrared region is associated with the semiconducting characteristics of PtSe2 which has interstitial Se atoms within the PtSe2 layers. It is also revealed that the PtSe2/GaAs photodetector does not exhibit performance degradation after six weeks in air. The generality of the above good results suggests that the vertically aligned PtSe2 is an ideal material for high-performance optoelectronic systems in the future.