Simulation-based study of low dark current phototransistors with p-hBN/AlGaN/GaN HEMT structures

In this work, we report a high-performance ultraviolet (UV) phototransistor (PT) based on p-GaN/AlGaN/GaN high electron mobility transistor (HEMT) structure. Under dark conditions, the conducting channel of the p-hBN HEMT-based UV PT is depleted by the p-n junction, resulting in a low dark current density of 2.29 × 10⁻¹² mA/mm under 10 V drain bias, which demonstrates three orders of magnitude suppression relative to the PTs employing p-GaN HEMT architectures. This can be attributed to the stronger depletion effect caused by the higher activation hole concentration in the p-hBN layer. Moreover, the photocurrent density reaches 228.91 mA/mm under 0.5 mW/cm² UV illumination. The photo-to-dark current ratio is 1 × 10¹⁴. Additionally, the impact of structural parameters on the performance of p-hBN HEMT-based PTs is investigated. These results demonstrate that the p-hBN HEMT-based PTs have applicable potential in UV detection applications, suggesting an alternative strategy for developing improved UV photodetectors.