Solar-Blind p-GaN/i-AlGaN/n-AlGaN Ultraviolet Photodiodes on SiC Substrate

Ultraviolet p–i–n photodiode structures have been fabricated using AlGaN/GaN and GaN structures grown on 6H-SiC. GaN photodiodes grown on 6H-SiC had lower leakage than GaN grown on sapphire. Solar-blind p-GaN/i-AlxGa1—xN/n-AlxGa1—xN (x ≈ 0.35) diodes were investigated. Leakage currents were measured to be as low as 10 nA/cm2 at —5 V. Use of a thick insulating buffer resulted in a peak responsivity of 0.08 A/W at a wavelength of 292 nm, corresponding to an external quantum efficiency of 35%.