Low-Frequency Noise Measurements of AlGaN/GaN Metal–Oxide–Semiconductor Heterostructure Field-Effect Transistors With HfAlO Gate Dielectric

We report on the low-frequency phase-noise measurements of AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors employing HfAlO as the gate dielectric. Some devices tested exhibited noise spectra deviating from the well-known 1/f^γ spectrum. These devices showed broad peaks in the noise spectral density versus frequency plots, which shifted toward higher frequencies at elevated temperatures. The temperature dependence of the frequency position of this peak allowed us to determine the energy level of these excess traps as 0.22 ± 0.06 eV below the conduction band for the bias conditions employed.