Simulating InP-based composite channel p-HEMTs with ultrashort gates for THz applications

Ultrashort gate length pseudomorphic highelectron-mobility transistors (p-HEMTs) based on an InP substrate and featuring a InAs/In
_0.053
Ga
_0.47
As composite channel have been modeled using a full-band Cellular Monte Carlo simulator. The affects of pair generation by impact ionization are included and we have incorporated a model to allow carriers to tunnel into and out of the channel. Using a gate length scaling analysis, we can obtain a theoretical upper limit for the cut-off frequency, f
_T
, which we find to be 1.7 THz for this specific type of structure. We also examine factors that may be preventing actual devices from achieving such high frequency operation.