Photoresponsivity of ultraviolet detectors based on InxAlyGa1-x-yN quaternary alloys

We describe the growth, fabrication, and characterization of an ultraviolet (UV) photoconductive detector based on InxAlyGa1-x-yN quaternary alloy tha t is lattice matched to GaN. The detector consisted of 0.1 mu m InxAlyGa1-x -yN alloy grown on 0.5-1.0 mu m GaN epilayer by metalorganic chemical vapor deposition. With varying indium concentration, the cut-off wavelength of t he InxAlyGa1-x-yN detectors could be varied to the deep UV range. The most important and intriguing result is that the responsivity of the InxAlyGa1-x -yN quaternary alloy exceeded that of AlGaN alloy of a comparable cutoff wa velength by a factor of five. This makes the nitride quaternary alloy very important material for solar blind UV detectors applications particularly i n the deep UV range where Al rich AlGaN alloys have problems with low quant um efficiency and cracks due in part to lattice mismatch with GaN. The adva ntages of InxAlyGa1-x-yN quaternary over AlGaN ternary alloys for UV detect or applications are also discussed. (C) 2000 American Institute of Physics. [S0003-6951(00)02331-7].