Abstract: Ohmic contacts of Ti/Al/Ni/Au multi-layer metal on Al0.27Ga0.73N/GaN heterostructures were fabricated.Specific contact resistivities were measured by the linear transmission line method (LTLM) and the circular transmission line method (CTLM),respectively.A minimum specific contact resistivity of 1.46E-5Ω·cm2 was obtained by evaporating a Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm) multi-layer and annealing for 30s at 650℃ in ultra-high purity N2 ambient.Al0.27Ga0.73N/GaN photoconductor ultraviolet (UV) photodetectors were prepared.The dark current-voltage (I-V) characteristics of the detectors were measured and the result shows that the I-V curve was linear.Experimental results indicate that good ohmic contact on the Al0.27Ga0.73N/GaN heterostructure is obtained and it can be applied in high-performance AlGaN/GaN UV photodetector fabrications.

Key words: AlGaN/GaN, ohmic contact, specific contact resistivity, transmission line method, Ti/Al/Ni/Au, ultraviolet detectors