Noise Analysis of AlGaN/GaN Metal-Oxide-Semiconductor Heterostructure Field Effect Transistors with Photochemical-Vapor Deposition SiO₂ Layers

Low frequency noise of AlGaN/GaN metal-oxide-semiconductor heterostructure field effect transistors (MOS-HFETs) with a photo-CVD SiO 2 gate oxide was investigated as a function of gate bias (from V gs =-8 V to V gs =4 V) in the linear region. In the linear region, the measured noise spectra were fitted well by the 1/ f law up to 10 kHz. The normalized noise power density of the MOS-HFETs was proportional to V gs -1 when -4 V< V gs <0 V and were independent of the gate voltage when the devices were biased at V gs >0 V. Moreover, the normalized noise-power densities of both devices were inversely proportional to the drain-source distance when V gs >0 V. All the experiment data can be well explained by Hooge's Law. The Hooge's coefficients α ch and α s were estimated to be 10 -3 approximately.