We report AlGaN-based back-illuminated solar-blind Schottky-type ultraviolet photodetectors with the cutoff-wavelength from 280nm to 292nm without bias. The devices show low dark current of 2.1 x 10(-6) A/cm(2) at the reverse bias of 5 V. The specific detectivity D* is estimated to be 3.3 x 10(12) cmHz(1/2)W(-1). To guarantee the performance of the photodetectors, the optimization of AlGaN growth and annealing condition for Schottky contacts were performed. The results show that high-temperature annealing method for Ni/Pt Schottky contacts is effective for the reduction of leakage current
