Fabrication and characterization of Ni-based Schottky-type Al_xGa_(1-x)N ultraviolet photodetectors with different buffer conditions

摘要

We investigated the structural, optical, and electrical properties of Ni-based Schottky type Al_xGa_(1-x)N ultraviolet (UV) photodetectors. Three different types of Al_xGa_(1-x)N/GaN heterostructures were epitaxially grown on (0001) sapphire substrates by metal-organic chemical vapor deposition. We found that the thin Al_xGa_(1-x)N layer directly grown on the optimized GaN buffer layer showed the most excellent crystal quality and opto-electrical properties of Ni-based Schottky type UV photodetectors. We obtained a dark current of 0.1 nA at -1 V, a responsivity of 0.150 A/W at zero bias, and a specific detectivity D~* of 1.28 x 10~(14) cmHz~(1/2)W~(-1) at λ = 300 run for UV photodetectors with a 0.15-μm-thick Al_xGa_(1-x)N layer directly grown on a 3-μm - thick undoped GaN layer.