High‐performance UV detector based on AlGaN/GaN junction heterostructure‐field‐effect transistor with a p‐GaN gate

A UV photodetector based on an AlxGa1‐xN/GaN junction hetero‐field‐effect transistor (JHFET) with a p‐GaN gate was fabricated. The dark current density was as low as 10 nA/mm at a drain‐source bias of 5 V. When the JHFET was irradiated with 356 nm (∼400 μW/cm2) UV light, a photocurrent, of over 1 mA/mm with calculated responsivity of over 1 × 105 A/W was realized. Also, this device reacted to a flame. The responsivity is observed at a 4th‐order‐magnitude cutoff wavelength of approximately 370 nm, which correspond to the band edge of GaN. The decay and buildup response times are approximately 2.5 and 1.9 ms, respectively. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)