Influence of the Device Structure on the Electrical and Photodetector Properties of n‑MoS₂/p-GaSe Heterojunction Optoelectronic Devices

Van der Waals heterojunction devices are of great significance for developing high-performance optoelectronic devices. Here, a strategy has been introduced to effectively improve the performance of devices by designing their structure, and three types of devices based on MoS₂/GaSe heterojunctions were designed and fabricated. The results have demonstrated that device-III effectively decreases the recombination of the electrons in GaSe flakes by removing the non-heterojunction region and depleting the GaSe flake, which results in electron-dominated channel current and much better electrical performance than device-I and device-II, such as a larger rectification ratio of 1.6 × 10⁵ and an ideality factor of 1.06. Furthermore, a photodetector based on device-III exhibits high performance for self-driven photodetection under 532 nm light irradiation, including a responsivity of 249 mA/W, a specific detectivity of 3.6 × 10¹¹ Jones, an open-circuit voltage of 0.56 V, and a short response/recovery time of 10.5 μs/7.3 μs. The results introduced here provide a path to significantly improve the electrical properties of optoelectronic devices based on a 2D material heterostructure.