High-Performance Ultraviolet Avalanche Photodetector Based on <i>β</i>-Ga₂O₃/GaN/Si Heterostructures

Ultraviolet photodetectors (UV PDs), particularly those operating in the solar-blind region, are essential for applications in environmental monitoring, flame detection, space exploration, and communication systems. Traditional photomultiplier tubes (PMTs), though highly sensitive, are hindered by their large size, fragility, and high operating voltages. Semiconductor-based avalanche photodetectors (APDs) provide advantages, such as low operating voltage, compact size, and stable performance. However, the limited bandgap of silicon restricts its ultraviolet (UV) detection capabilities. Wide-bandgap semiconductors such as GaN and gallium oxide (Ga2O3) show great promise due to their high-UV sensitivity and low dark current. Here, we report the fabrication of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3/GaN/Si homojunction heterostructure UV APD. The device exhibited an exceptionally low dark current of <1 pA, a stable gain exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.5\times 10^{{3}}$ </tex-math></inline-formula>, and a maximum responsivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7\times 10^{{3}}$ </tex-math></inline-formula> A/W. In addition, the detectivity surpassed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 10^{{14}}$ </tex-math></inline-formula> Jones. The results establish the device’s excellent UV selectivity and compatibility with CMOS processes, offering a pathway to compact and efficient optoelectronic integration.