Scaling issues for AlGaN/GaN HEMTs: performance optimization via devices   geometry modelling
  The potential barrier between source and gate in HEMTs and between source and channel in MOSFET controls the current output and the velocity injection of electrons in the channel [1], [2]. In non self aligned structures the electric field behavior along the channel, for fixed applied voltages, is determined by the contacts positions. Anyway, in GaAs based HEMTs, the geometry of the device appears to be not determinant for the output current due to saturation effects. On the other hand, the GaN based technology still offers the possibility to enhance devices output current handling contacts distances. In this paper we will present Monte Carlo simulations results which show how a downscaling of the Source to Gate distance could improve the device performances inducing an higher potential barrier between source and gate. 
S. Russo, A. Di Carlo