  We report on the potential of high electron mobility transistors (HEMTs)
consisting of high composition AlGaN channel and barrier layers for power
switching applications. Detailed 2D simulations show that threshold voltages in
excess of 3 V can be achieved through the use of AlGaN channel layers. We also
calculate the two-dimensional electron gas (2DEG) mobility in AlGaN channel
HEMTs and evaluate their power figures of merit as a function of device
operating temperature and Al mole fraction in the channel. Our models show that
power switching transistors with AlGaN channels would have comparable
on-resistance to GaN-channel based transistors for the same operation voltage.
The modeling in this paper shows the potential of high composition AlGaN as a
channel material for future high threshold enhancement mode transistors.
