Sulfurization engineering of single-zone CVD vertical and horizontal MoS(2) on p-GaN heterostructures for self-powered UV photodetectors

Molybdenum disulfide (MoS(2)) has been attracting considerable attention due to its excellent electrical and optical properties. We successfully grew high-quality, large-area and uniform few-layer (FL)-MoS(2) on p-doped gallium nitride (p-GaN) using a simplified sulfurization technique by the single-zone CVD of a Mo seed layer via E-beam evaporation. Tuning the sulfurization parameters, namely temperature and duration, has been discovered to be an effective strategy for improving MoS(2) orientation (horizontally aligned and vertically aligned) and quality, which affects photodetector (PD) performance. The increase in the sulfurization temperature to 850 °C results in improved structural quality and crystallite size. However, a prolonged sulfurization duration of 60 minutes caused the degradation of the film quality. The close lattice match between p-GaN and MoS(2) contributes to the excellent quality growth of deposited MoS(2). Following this, an n-MoS(2)/p-GaN heterostructure PD was successfully built by a MoS(2) position-selectivity method. We report a highly sensitive and self-powered GaN/MoS(2) p–n heterojunction PD with a relatively high responsivity of 14.3 A W(−1), a high specific detectivity of 1.12 × 10(13) Jones, and a fast response speed of 8.3/13.4 μs (20 kHz) under a UV light of 355 nm at zero-bias voltage. Our PD exhibits superior performance to that of the previously reported MoS(2)/GaN p–n PD. Our findings suggest a more efficient and straightforward approach to building high-performance self-powered UV PDs.