Low-intensity ultraviolet photodetectors based on AlGaN

We report on the fabrication and the characterization of low-intensity ultr aviolet (UV) photodetectors based on AlxGa1-xN frown by organometallic vapo r phase epitaxy, with threading dislocation density in the range of 5-8 x 1 0(9) to 2 x 10(11) cm(-2) and 6-7 x 10(7) to 1 x 10(9) cm(-2). The detector s present dark current values below 100 fA at 10 V bias allowing a photocur rent to dark current ratio greater than one even at 40 nW/cm(2). The photod etectors fabricated on low-density dislocation layers present a greatly red uced persistent photoconductivity. Also, they achieved a rejection ratio of 3 orders of magnitude between UV and visible light with cutoffs at 365 and 270 nm for x = 0 and x = 0.43, respectively.