Nonequilibrium and ballistic transport, and backscattering in decanano HEMTs: a Monte Carlo simulation study

High electron mobility transistors (HEMTs) based on III–V semiconductor materials have been investigated as these devices are scaled down to gate lengths of 120, 90, 70, 50 and 30nm. A standard Monte Carlo (MC) method coupled with the solution of Poisson’s equation is employed to simulate a particle transport. The average particle velocity and the field–momentum relaxation time are studied in detail along the pseudomorphic HEMT (PHEMT) channel for two possible approaches to scaling. Nonequilibrium and ballistic transport dominate at gate lengths of 120 and 70nm. However, velocity saturation is observed in the 50nm gate length PHEMT which is due to strong scattering including backscattering. In addition, single and double delta doping designs are also compared. Our work indicates that the 70nm double doped PHEMT is the most suitable design to further increase the device transconductance.