Experimental Demonstration of Avalanche Noise in GaN PN Junctions Grown on Native GaN Substrates

Abstract

GaN pn junction diodes grown on native GaN substrates have been fabricated and characterized. The temperature-dependent current-voltage characteristics exhibit a positive temperature coefficient of breakdown as expected from impact ionization avalanche. However, for IMPATT and avalanche photodiode applications, device noise is very important. The low frequency noise characteristics of these devices have been measured under forward and reverse bias conditions. The forward noise spectra is dominated by 1/f noise, and the current spectral density is proportional to I1.6. Under reverse bias, the noise spectra show 1/f noise at reverse biases below the avalanche threshold. However, at reverse biases in the avalanche regime, the multiplication noise overwhelms the 1/f noise, resulting in a white noise spectrum. The measured results are consistent with expectations from avalanche noise theory.