Transformation in Low-Frequency Noise Spectra in GaN High-Electron-Mobility Transistors in Nonequilibrium Conditions

It is known that flicker noise is the most intriguing noise component because it can be found in any type of material, object, device, or system. Despite the struggle of scientists to find a mutual model for the 1/f flicker noise law, there is still a challenge to describe the law in many cases. Herein, the studies of two-level random telegraph signal (RTS) fluctuations analyzed for the state-of-the-art high-electron-mobility transistors (HEMTs), fabricated based on AlGaN/GaN heterostructures, are presented. It is revealed that the shape of the fluctuations can be used to describe the formation of a 1/ f gamma spectrum with gamma = 1, 2, 3. The data demonstrate that the 1/f spectrum can be obtained as a result of the interactions of the carriers in parallel channels along the length of a system. Experimentally registered RTS fluctuations have a spectrum described by 1/ f gamma behavior. The data are in good agreement with the theoretically predicted pulsed shape, allowing the generation of a 1/f spectrum. Based on the data analysis and the theoretical description of the fluctuations, the origin of 1/f fluctuations in nonequilibrium conditions is explained by interactions resulting in correlations of carriers in two parallel channels as the common feature in the HEMT devices.