GaN/Ga₂O₃ avalanche photodiodes with separate absorption and multiplication structure

This article proposes a new, to the best of our knowledge, separate absorption and multiplication (SAM) APD based on GaN/β-Ga₂O₃ heterojunction with high gains. The proposed APD achieved a high gain of 1.93 × 10⁴. We further optimized the electric field distribution by simulating different doping concentrations and thicknesses of the transition region, resulting in the higher avalanche gain of the device. Furthermore, we designed a GaN/β-Ga₂O₃ heterojunction instead of the single Ga₂O₃ homogeneous layer as the multiplication region. Owing to the higher hole ionization coefficient, the device offers up to a 120% improvement in avalanche gain reach to 4.24 × 10⁴. We subsequently clearly elaborated on the working principle and gain mechanism of GaN/β-Ga₂O₃ SAM APD. The proposed structure is anticipated to provide significant guidance for ultraweak ultraviolet light detection.