  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.
