High-Performance β-Ga₂O₃ MISIM Solar-Blind Photodetectors With an Interfacial AlN Layer

We report on $\beta $ -Ga2O3-based metal-semiconductor-metal (MSM) and metal-insulator-semiconductor-insulator-metal (MISIM) solar-blind photodetectors with high responsivity and high speed. The $\beta $ -Ga2O3 MSM photodetector exhibits a low dark current of 8.91 pA, a high responsivity of 247 A/W, a high response speed of 0.32 s, and a high external quantum efficiency (EQE) of $1.21\times 10^{5}$ %, which is ascribed to high-quality film grown by molecular beam epitaxy. Interestingly, the performance of $\beta $ -Ga2O3 MSM photodetector can be tuned in trade-off balance by inserting an ultrathin interfacial AlN layer by atomic layer deposition. The $\beta $ -Ga2O3 MISIM photodetector with a 3 nm AlN interfacial layer shows an improved responsivity of 482 A/W, a higher EQE of $2.36\times 10^{5}$ %, and a faster response time of 0.10 s, and a deteriorating dark current of 0.17 nA. Additionally, a type I band alignment at the AlN/ $\beta $ -Ga2O3 interface is identified by X-ray photoelectron spectroscopy and the corresponding migration of carriers at the interface are used to explain the observed results. Our study suggested a great potential for high-performance $\beta $ -Ga2O3 photodetectors through an AlN-engaged interfacial engineering.