Longhui Zeng, Shenghuang Lin, Zhong-jun Li, Zhixiang Zhang, Tengfei Zhang, Chao Xie, Yang Chai, Shu Ping Lau, Lin-Bao Luo,* Yuen Hong Tsang*

Abstract: Group-10 layered transitional metal dichalcogenides (TMDs) including PtS₂, PtSe2 and PtTe2 are regarded as potential candidates for optoelectronic devices application due to their unique properties such as high carrier mobility, tunable bandgap, stability and flexibility. As an interesting and attractive layered material, large area platinum diselenide (PtSe2) is thus far scarcely investigated. Here, we report on the development of a high performance photodetector based on vertically standing PtSe2-GaAs heterojunction which exhibited a broadband sensitivity to illumination ranging from deep ultraviolet (DUV) to near infrared (NIR) light, with peak sensitivity at round 650 nm. Optoelectronic analysis revealed that the Ilight/Idark ratio and responsivity (R) of photodetector were about 2×103 and 122.64 mA W−1 measured at 650 nm at zero bias voltage. According to theoretical simulation based on first-principle density functional theory, the peaks sensitivity at 650 nm is associated with the interstitial Se atoms. The response speed was estimated to around 18 μs, which represented the best result achieved for Group-10 TMDs based optoelectronic device thus far. It was also revealed that the PtSe2/GaAs photodetector did not exhibit obvious performance degradation after exposure it in air for 6 weeks.