A Study on Step-Barrier Structures for Radio Frequency AlGaN High Electron Mobility Transistors

Abstract

The barrier layer for an Aluminum Gallium Nitride (AlGaN) High Electron Mobility Transistor (HEMT) on silicon is studied. The objective is to optimize the high frequency performance with a practical fabrication process. Devices with standard barrier layers and step-barrier structures are simulated and analysed using Sentaurus Technology Computer Aided Design (TCAD) and correlated with experimental results. An AlGaN HEMT with an optimized step-barrier structure can attain a unity current gain frequency of ft = 52 GHz, a 21% increase when compared to the standard device. Based on trends in the unity current gain frequency, a method for determining the critical thickness of the step-barrier is proposed.