Megahertz bandwidth AlxGa1-xN/GaN-based pin detectors

This paper discusses recent results of time response and spectral responsivity measurements made on AlxGa1-xN/GaN-based p-i-n ultraviolet (UV) detectors with .03<x<0.12, where x is the aluminum concentration. AlxGa1-xN/GaN-based p-i-n detectors with response times (1/e) as fast as 6 ns corresponding to greater than 26 MHz bandwidths are reported. Peak spectral responsivities of homojunction Al.03Ga.97N p-i-n UV detectors were found to be as high as 0.08-A/W at 343 nm while those of the Al.1Ga.9N/GaN p-i-ns were as high as 0.15 A/W at 360 nm. Homojunction GaN and Al.03Ga.97N as well as p-Al.1Ga.9N/i-GaN/n-GaN (heretofore referred to as Al.1Ga.9N/GaN) structures were grown on sapphire substrates by reactive molecular beam epitaxy (MBE) and processed into UV detectors. These p-i-n detectors were then characterized in terms of their time response and spectral responsivity. Attempts to measure the noise of the Al.03Ga.97N homojunction p-i-ns are also discussed.