Solar-blind Al <i> _x </i> Ga _{1- <i>x</i>} N-basedmetal-semiconductor-metalultraviolet photodetectors

Abstract

Solar-blind Schottky metal-semiconductor-metal photodetectors fabricated on epitaxial Al0.4Ga0.6N layers grown by metalorganic chemical vapour deposition are reported. The devices exhibit low dark current and an external quantum efficiency as high as 49% (at λ = 272 nm) at 90 V bias, with a corresponding responsivity R = 107 mA/W. A visible-to-UV rejection factor of more than three orders of magnitude is demonstrated. The 3 dB bandwidth is 100 MHz and the detectivity is estimated to be 3.3 × 1010 cm·Hz1/2/W.