Two-Dimensional MoS2 on p-Type GaN for UV–Vis Photodetectors

In this study, we employ the sol–gel method to fabricate MoS2 films with a controllable thickness. The resulting colloidal configuration can be directly spin-coated onto various substrates (e.g., Si, SiO2, GaN, and sapphire), leading to the formation of smooth MoS2 films after annealing. Based on this technique, we construct a two-dimensional MoS2/p-GaN van der Waals (vdWs) heterostructure photodetector comprising n-MoS2 and p-GaN. The high crystal quality of MoS2 and the internal electric field of the MoS2/p-GaN heterostructure p–n junction enable efficient separation of photogenerated carriers, resulting in enhanced exciton collection by the electrode at 416 nm. This configuration achieves a high photo response of 35.6 A/W and a rapid response time of 200 ms, surpassing that of a single MoS2 thin film. Furthermore, when combined with p-GaN, the photodetector's response spectrum extends to the ultraviolet region, exhibiting an impressive 8.4 A/W light response and a quick response time of 280 ms. This demonstrates a favorable synergistic effect. These exceptional properties establish n-MoS2/p-GaN heterostructure photodetectors as highly competitive next-generation optoelectronic devices.