AlGaN/GaN heterostructures for UV photodetector applications

Metalorganic vapour phase expitaxy (MOVPE) process parameters of AlxGa1-xN 0<x<0.3) layers grown on c- oriented sapphire substrates were optimised from the point of view of their application in photoconductive and MSM type photodetectors. The low temperature AlN was used as a nucleation layer. The layers electrical properties were determined by C-V measurements performed in the range 5 Hz + 13 MHz with HP 4192A impedance meter using a mercury probe. The optical characterisation of AlxGa1-xN was performed by photoluminescence measurement at liquid He and room temperature. The aluminium mole fraction in the layers were determined and compared to the results derived from the X-ray diffraction measurements. The photoconductive defectors were fabricated with Ti/Al/Ni/Au ohmic contacts. The I-V characteristics were taken and the photoresponse of the detectors was measured.