Flexible Ultraviolet Photodetector Based on 2D MoS₂/Ga₂O₃ Heterojunction

Flexible electronics have brought attention due to their widespread applications such as wearable sensors, artificial e skin, portable and low-cost disposable devices. Combining the 2D TMDCs with conventional semiconductor materials is a feasible route to fabricate high-performing heterojunction devices. In this work, a high-performance flexible UV-photodetector based on trilayer MoS₂/ Ga₂O₃ heterostructure is demonstrated. First, Ga₂O₃ was grown over a flexible substrate (Muscovite mica) using the pulse laser deposition (PLD) technique. After that, CVD-grown MoS₂ was transferred onto Ga₂O₃ using the Quasi-dry transfer process without degradation of film quality. Optical microscope, SEM, and AFM results show that transferred film is highly clean and damage-free. Through the KPFM and XPS/UPS measurements, we have investigated a type I band alignment of heterojunction. In the deep UV region (260 nm), the photocurrent was enhanced 100 times to dark current. The photoresponsivity of 0.05 A/W was obtained for 5 V applied bias at room temperature under 20 μW/cm² illuminations. The device performance was also studied at different bending radius. A negligible change was observed in photocurrent and photoresponsivity during the bending of the device. Moreover, photocurrent and dark current characteristics above room temperature demonstrate the outstanding functionalities until 500 K temperature, which is remarkable for flexible photodetectors. The obtained results show the enormous potential for futuristic smart and flexible devices.