Fast response and high-performance UV-C to NIR broadband photodetector based on MoS2/a-Ga2O3 heterostructures and impact of band-alignment and charge carrier dynamics

Recently, 2D materials have gained tremendous research interest due to their unique properties in electronics and optoelectronics. However, single 2D material-based photodetectors suffer from limitations such as narrow spectral sensitivity and slow response time due to bandgap restriction and difficulty in charge extraction. A heterojunction, which separates photo-excited electron-hole pairs and tunes absorption edge through appropriate selection of semiconductors with complementary bandgaps, is an effective strategy for broad spectral energy-conserving photodetection. This study presents a scalable 2D/3D heterostructure of MoS2/Ga2O3 with outstanding UV-C to NIR broad spectral photoresponse. The MoS2/Ga2O3 photodetector demonstrated a 315-fold increase in responsivity and EQE compared to pristine MoS2 photodetector. The device showed highest responsivity and EQE of 171 AW−1 and 2.4 × 104 % respectively under 900 nm illumination at 5 V bias. The device also exhibits high detectivity (4.6 × 1013 Jones) and fast response time of 97 µs. Moreover, the device is highly stable and shows no performance degradation over time. The device behavior was investigated through energy band diagrams and charge carrier dynamics using photoelectron spectroscopy and Kelvin probe force microscopy to gain intrinsic physical insights. The demonstration of MoS2/Ga2O3 as a high-performance broadband photodetector offers exciting opportunities for efficient optoelectronics and imaging applications.