We examined the control of the detection wavelength in AlGaN/GaN-based hetero-field-effect-transistor (HFET) photosensors. The detection wavelength of these devices can be controlled by using the p-GaInN optical gate or inserting a GaInN channel layer between AlGaN and GaN. In addition, the photosensitivity of AlGaN/GaN HFET photosensors with a p-GaInN optical gate was more than two orders of magnitude higher than that of the AlGaN/GaN HFET photosensor with a GaInN channel layer. Moreover, the photosensitivity of the AlGaN/GaN HFET photosensor with a p-GaInN optical gate greatly surpassed those of commercially available Si pin and Si avalanche photodiodes, and was comparable to those of photomultiplier tubes.

AlGaN/GaN hetero‐field‐effect‐transistor‐type (HFET‐type) photosensors are fabricated with a p‐GaInN optical gate for the detection of visible light. These photosensors employ a two‐dimensional electron gas at the heterointerface between AlGaN and GaN as a highly conductive channel with a high electron mobility. By changing the InN molar fraction in the p‐GaInN optical gate, the wavelength range of the photosensitivity of the HFET‐type photosensors can be controlled. The photosensitivity of the AlGaN/GaN HFET‐type photosensors with a p‐GaInN optical gate greatly surpassed those of commercially available Si pin and Si avalanche photodiodes, and was comparable to those of photomultiplier tubes. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)