The upper limits of cut-off frequency in ultra-short gate length InP-based p-HEMTs

Ultrashort gate length pseudomorphic high-electron-mobility transistors (p-HEMTs) based on an InP substrate have been modeled using a full-band cellular Monte Carlo simulator. The RF response has been obtained for lithographic gate lengths ranging from 10 nm to 50 nm and for channel thicknesses of 18 and 10 nm. These results in turn have been used in a transit time analysis to determine the effective gate length in each case. By interpolation, one can make an estimate of the absolute upper limit for the cut-off frequency, f_T, which we find to be 2.9 THz in 18 nm device and 3.1 THz in the 10 nm device.