Ultrahigh Responsivity and High-Detectivity Lateral GaN Ultraviolet Nanogap Field-Emission Photodiodes

Vacuum nanoelectronic-based photodetectors operating via photoassisted field emission have the potential for significantly improved performance and robust operation under high-temperature and high-radiation environments. Here we demonstrate on-chip, GaN-based UV lateral nanogap field-emission photodiodes (NFEPs) with bandgap-dependent ultrahigh responsivity up to 2.21 × 107 A/W and corresponding detectivity of 5.0 × 1014 cm Hz1/2 W-1. The high performance is proposed to occur by a surface photovoltage effect that dramatically lowers the barrier for field emission across the nanogap upon above-bandgap illumination. These results show promise toward a new class of integrated and high-performance, bandgap-tunable, deep-UV photodetectors operable in harsh environments.