High-Speed Ultraviolet Photodetector Based on p-GaN Gate HEMT for Flame Monitoring

The p-GaN gate high electron mobility transistor (HEMT) with a $2.0\times 10^{-{5}}$ cm2 sensitive area as a UV photodetector (PD) has been designed and fabricated in this study. AlGaN/gallium nitride (GaN) heterostructure was adopted to get a 2-D electron gas (2DEG) as a conductive channel, resulting in a high photoresponsivity of $8.07\times 10^{{4}}$ A/W, a sharp cutoff wavelength at 360 nm, high UV-to-visible rejection ratio of $1.80\times 10^{{6}}$ , rise and decay time of 0.12 and 1.0 ms, respectively. The dark current of $5.44\times 10^{-{7}}$ A, the photocurrent of $4.42\times 10^{-{3}}$ A at 5 V, the external quantum efficiency (EQE) of 2.77% $\times 10^{{5}}$ %, and the detectivity of $8.31\times 10^{{14}}$ Jones for the UV PD were determined under a low UV light intensity of 5 mW/cm2 at 360-nm UV illumination. The obtained results show that the performance of as-fabricated UV PD based on AlGaN/GaN HEMT is significantly improved compared to the literature. This device, which has lower noise equivalent power (NEP) and enhanced detectivity features compared to existing ones, is a promising candidate for military and space applications.