High-Speed Broadband PtSe2/Si 2D-3D Pin Photodetector with a Lightly n-Doped Si Interlayer Based on Single-Oriented PtSe2

Platinum diselenide (PtSe2), which is a member of transition metal dichalcogenides (TMDs), has aroused significant attention as a promising candidate for high-performance photodetection, owing to its distinctive properties and tunable interlayer band gap. However, the growth of the single-crystal PtSe2 film remains a challenge, while the two-dimensional (2D)/three-dimensional (3D) heterojunction photodetector (PD) based on PtSe2 is generally fabricated by directly combining the film with the substrate. Here, we report an effective method for synthesizing 2 in. single-oriented PtSe2 films in a large diameter cavity by thermally assisted conversion (TAC). Meanwhile, a kind of PD based on the PtSe2/n–-Si/n+-Si pin structure is proposed for the first time. For comparison, other PDs based on the PtSe2/Si pn structure are also fabricated. The pin device exhibits a 3 dB frequency of ∼125 kHz, a response speed of 2.2/11.8 μs under the illumination at 532 nm, and a good response under the illumination at 1310, 1550, 1850, and 2200 nm for infrared image sensing. It has been demonstrated that the shorter carrier transit time and better control ability of the electric field can be responsible for the outstanding performance of the pin device. This work provides a potential to develop Si-based integrated optoelectronics with an ultrafast response and a guideline for designing the next-generation pin PD based on 2D materials.