Investigation of flicker noise and deep-levels in GaN/AlGaN transistors

We report flicker noise measurements combined with deep-level transient spe ctroscopy of the doped and undoped channel GaN/AlGaN heterostructure field- effect transistors. The low-temperature noise spectra for the doped devices show clear generation-recombination peaks. The value of the activation ene rgy extracted from these noise peaks is consistent with the activation ener gies measured using deep-level spectroscopy. Our results indicate that the input-referred noise spectral density of the undoped channel devices is muc h smaller (up to two orders of magnitude) than that of the doped channel de vices with comparable electric characteristics. The additional defects due to doping add up to the generation-recombination and flicker noise.