A photodetector is described. The photodetector is comprised of a substrate, a first n-type III-V compound semiconductor layer located on the substrate, an n++-type III-V compound semiconductor layer located on a first portion of the first n-type III-V compound semiconductor layer with a second portion of the first n-type III-V compound semiconductor layer exposed, a p-type III-V compound semiconductor layer located on the n++-type compound semiconductor layer, an undoped III-V compound semiconductor layer located on the p-type III-V compound semiconductor layer, a second n-type III-V compound semiconductor layer located on the undoped III-V compound semiconductor layer, a conductive transparent oxide layer located on the second n-type III-V compound semiconductor layer, a first electrode located on a portion of the conductive transparent oxide layer, and a second electrode located on a portion of the second portion of the first n-type III-V compound semiconductor layer.