Gated photodetector based on GaN/AlGaN heterostructurefieldeffect transistor

The authors report a 0.2 µm gate GaN/AlGaN heterostructure field effect transistor which operates as a visible blind photodetector with responsivities as high as 3000 A/W for wavelengths from 200 to 365 nm. The responsivity falls by three orders of magnitude for wavelengths greater than 365 nm. Using a CW He-Cd laser (wavelength 325 nm), we measured a response time of order 0.2 ms. A model explaining the detector operation is in good agreement with the experimental data.