Monolithic Integration of Strained UV-Visible Dual Color Photodetectors on 4 in. Multilayer MoS₂-on-Freestanding GaN Wafer by Direct van der Waals Growth

MoS2/GaN van der Waals heterojunction is suitable for the multiband photodetection field due to the nearly lattice match and excellent response capabilities in ultraviolet and visible light regions. In this work, a multilayer MoS2/GaN van der Waals heterojunction was grown by the chemical vapor deposition method and fabricated into an integrated ultraviolet-visible photodetector. Tensile strain was introduced on MoS2/GaN by depositing Al2O3 stress liner using atomic layer deposition. Owing to the tensile strain effect, excellent detection performances were demonstrated, including a responsivity as high as 1.4 × 105 A/W, a noise equivalent power of 5.63 × 10-21 W/Hz1/2, a normalized detectivity of 6.13 × 1021 jones for stress liner GaN photodetector under 280 nm illumination, and 453.3 A/W for stress liner MoS2 photodetector under 460 nm illumination. The shortened response time of the photodetector is attributed to the improved carrier mobility and the separation of MoS2 from air by Al2O3. This work has provided significant guidance for the development of integrated circuits and optical chips.