ALXGA1-XN-SI SCHOTTKY-BARRIER PHOTODIODES WITH FAST-RESPONSE AND HIGHDETECTIVITY

Gold and nickel Schottky barrier photovoltaic detectors have been fabr icated on Si-doped AlxGa1-xN layers (0 less than or equal to x less th an or equal to 0.22) grown on sapphire by metalorganic vapor phase epi taxy. Responsivity is independent of the Schottky metal or diode size, and also of the incident power in the range measured (10 mW/m(2)-2 kW /m(2) A higher visible rejection has been observed in the spectral res ponse of Au photodiodes (10(3)). Time response is resistance-capacitan ce limited, with time constants as short as 14 ns in Al0.22Ga0.78N dio des. Low frequency noise studies are also presented, and detectivities of 6.1 x 10(7) and 1.2 x 10(7) mHz(1/ 2) W-1 are determined in GaN/Au and Al0.22Ga0.78N/Au detectors, at -2 V bias. (C) 1998 American Insti tute of Physics. [S0003-6951(98)02941-6].