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

Van der Waals heterojunction devicesare of great significancefor developing high-performance optoelectronic devices. Here, a strategyhas been introduced to effectively improve the performance of devicesby designing their structure, and three types of devices based onMoS(2)/GaSe heterojunctions were designed and fabricated.The results have demonstrated that device-III effectively decreasesthe recombination of the electrons in GaSe flakes by removing thenon-heterojunction region and depleting the GaSe flake, which resultsin electron-dominated channel current and much better electrical performancethan device-I and device-II, such as a larger rectification ratioof 1.6 x 10(5) and an ideality factor of 1.06. Furthermore,a photodetector based on device-III exhibits high performance forself-driven photodetection under 532 nm light irradiation, includinga responsivity of 249 mA/W, a specific detectivity of 3.6 x 10(11) Jones, an open-circuit voltage of 0.56 V, and a short response/recoverytime of 10.5 & mu;s/7.3 & mu;s. The results introduced here providea path to significantly improve the electrical properties of optoelectronicdevices based on a 2D material heterostructure.