Growth and characteristics of Ni-based Schottky-type AlxGa1-xN ultraviolet photodetectors with AlGaN/GaN superlattices

Abstract

We investigated the structural, optical, and electrical properties of Ni-based Schottky-type AlxGa1-xN ultraviolet (UV) photodetectors. Three different types of AlxGa1-xN/GaN heterostructures were epitaxially grown on (0001) sapphire substrates by metalorganic chemical vapor deposition. We found that the insertion of Al0.2Ga0.8N/GaN superlattices (SLs) improved the crystal quality of AlxGa1-xN/GaN heterostructures from photoluminescence and x-ray diffraction experiments. As a result, AlxGa1-xN UV photodetectors with Al0.2Ga0.8N/GaN SL layers showed superior device performance with lower turn-on voltage and higher responsivity compared to those without SLs. We obtained a dark current of 0.1 nA at -5 V, a responsivity of 0.097 A/W at zero bias, and a specific detectivity of D-*=8x10(13) cm Hz(1/2) W-1 at lambda=290 nm for AlxGa1-xN UV photodetectors with Al0.2Ga0.8N/GaN SLs. (c) 2005 American Institute of Physics.