AlGaN and GaN ultraviolet photodetectors

Reported here are visible blind, UV GaN p-i-n photodetectors which have been fabricated on 3-inch diameter (0001) sapphire substrates and UV AlGaN MSM photodetectors which have been fabricated on 2-inch diameter substrates. The GaN p-i-n photodetectors exhibited a peak spectral responsivity of 0.194 A/W at 359 nm with 4-6 orders of magnitude visible rejection. The MSM photodetectors, which were fabricated from AlGaN with a near bandgap luminescent peak of 320 nm, exhibited substantial photoconductive gain which yielded 7 AMI responsivity at 250 nm, 1.7 A/W responsivity at 320 nm and more the 5 orders of magnitude visible tight rejection. Spectral responsivity uniformity of the GaN p-i-n photodetectors across a 3-inch wafer was measured to be 12% (1 sigma). Both 100 Hz and 1 kHz 1/f noise power density for the GaN p-i-n photodiodes were found to be on the order of 10(-30) A(2)/Hz at room temperature.