Fast, Self‐Driven, Air‐Stable, and Broadband Photodetector Based on Vertically Aligned PtSe 2 /GaAs Heterojunction

Abstract Group‐10 layered transitional metal dichalcogenides including PtS 2 , PtSe 2 , and PtTe 2 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 (PtSe 2 ) with semiconducting characteristics is far scarcely investigated. Here, the development of a high‐performance photodetector based on vertically aligned PtSe 2 ‐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 × 10 4 and 262 mA W −1 measured at 808 nm under zero bias voltage. The response speed of τ r /τ f is 5.5/6.5 µs, 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 PtSe 2 which has interstitial Se atoms within the PtSe 2 layers. It is also revealed that the PtSe 2 /GaAs photodetector does not exhibit performance degradation after six weeks in air. The generality of the above good results suggests that the vertically aligned PtSe 2 is an ideal material for high‐performance optoelectronic systems in the future.