Metal-semiconductor-metal (MSM) ultraviolet photodetectors were successfully fabricated and characterized. Al 0.16 Ga 0.84 N/GaN heterostructures with HT-AlN interlayer whose thicknesses ranged from 30 to 70 nm were grown on sapphire (0001) to achieve high performance MSM UV photodetectors by MOCVD. The HT-AlN interlayer with a thickness of 30 nm showed the best results in terms of quality, so we fabricated and characterized MSM UV photodetectors with an interdigitated finger pattern using the Al 0.16 Ga 0.84 N/GaN heterostructure incorporating this layer. Their responsivity was 0.2 A/W under -10 V bias at a sharp cut-off of 330 nm. A fast response time of 15.4 ns was achieved, and the dark current of 3.1 pA/cm 2 under zero bias shows that low leakage current was achieved.