Self-Powered Horizontally Structured n-n Heterojunction Photodetector Based on Si-GaN/β-Ga2O3 for UV Detection

Abstract With the rapid advancement of optoelectronic technology, high-performance photodetectors are increasingly in demand in fields such as environmental monitoring, optical communication, and defense systems, where ultraviolet detection is critical. However, conventional semiconductor materials suffer from limited UV-visible detection capabilities owing to their narrow bandgaps and high dark currents. To address these challenges, wide-bandgap semiconductors have emerged as promising alternatives. Here, we fabricated a horizontally structured n-n heterojunction photodetector by growing β -Ga 2 O 3 on Si-GaN via plasma-enhanced chemical vapor deposition. The device exhibits a self-powered photocurrent of 3.5 nA at zero bias, enabled by the photovoltaic effect of the space charge region. Under 254 nm and 365 nm illumination, it exhibits rectification behavior, achieving a responsivity of 0.475 mA/W (0 V, 220 μ W/cm 2 at 254 nm) and 257.6 mA/W (-5 V), respectively. Notably, the photodetector demonstrates a high photocurrent-to-dark current ratio of 10⁵ under -5 V bias, highlighting its potential for self-powered and high-performance UV detection applications.