Origin of noise in AlGaN∕GaN heterostructures in the range of 10–100MHz

Abstract

We report on the noise origin in AlGaN∕GaN heterostructures for the frequency range of 10–100MHz. High electron mobility transistor heterostructures were designed for high-power and high-frequency application and grown on SiC substrates. The structures were patterned with Ohmic transmission line model (5, 10, 15, 20, and 25micrometer working distances) contacts and were analyzed using I-V characteristics and noise figure measurements. Different possible mechanisms of noise origin were considered and investigated in detail. The results of our analysis show that the thermal noise and hot carrier noise play a minor role in the structure in the investigated frequency range. At the same time, a dominant generation-recombination (G-R) noise is revealed. Moreover, two different components of G-R noise are found demonstrating different temperature dependences and as a result different physical origins of the noise are established. A detailed analysis of potential profiles of the structure calculated self-consistently for several voltages allows us to propose a physical model for the observed noise behavior. The fluctuations of electron concentration on the first quantum level of the quantum well and the scattering of the electrons in the barrier layer play a definite role in the noise phenomena.