MONTE-CARLO SIMULATION OF INP AND GAAS-MESFETS

We have performed Monte Carlo simulations of InP MESFETs of lengths 0. 6, 0.9 and 1.2 mu m and compared these results with those on GaAs MESF ETs of the same dimensions. The direct current IV characteristics of t he two materials were found to be similar though the GaAs characterist ics were on the whole superior, reaching their operating point at lowe r drain voltages and possessing higher gains. However, oscillations in the drain current caused by changes in drain voltage in the GaAs devi ces were not present to the same degree in the InP devices. This diffe rence is caused partially by the onset of the negative differential re gime in InP at a higher electric field than in GaAs but the primary ca use is the longer ballistic transport times in InP. This suggests that InP MESFETS may prove to have superior frequency response characteris tics than GaAs MESFETs.