Requirements for low intermodulation distortion in GaN-Al/sub x/Ga/sub 1-x/N high electron mobility transistors: a model assessment

A model analysis of the large-signal characteristics of GaN-Al/sub x/Ga/sub 1-x/N high-electron mobility transistors (HEMTs) with particular emphasis on intermodulation distortion (IMD) and the third-order intercept point. Since the nonlinearity depends critically on the carrier transport behavior, a Monte Carlo (MC) based numerical simulation scheme has been employed. The focus is to identify parameters and their interdependencies with a view of setting optimal limits for enhanced microwave performance. A case is made for increased mole fraction for the barrier layer, reducing the transit length, and introducing a thin AlN interfacial layer for suppressing real space transfer for enhancing the device performance. Finally, high-temperature predictions of the nonlinear behavior and IMD have been made, by carrying out the MC simulations at 600 K. In a process a favorable case is made for the GaN system as a potential candidate for microwave and RF applications at elevated temperatures.