Hot electron effects in ultra-short gate length InAs/lnAlAs HEMTs

High field transport in short channel (sub-100 nm gate length), InAs/InAlAs pseudomorphic high-electron mobility transistors (pHEMTs) has been studied using a full-band Cellular Monte Carlo (CMC) simulator. Reasonable agreement is obtained between simulated devices and recent experimental results in terms of the current, voltage and cutoff frequency. Both 70 nm and 35 nm gate length devices have been simulated in this work. Sustained high carrier energies near the drain electrode are observed and attributed to the long scattering times from both X and L valleys back to the Γ valley in InAs. Strong overshoot effects are also apparent in the velocity, although the corresponding increase in cutoff frequency is not as pronounced as expected from simple scaling of the gate length. The relation of this velocity behaviour to the experimental and simulated frequency response is discussed, as well as the limits of performance in this technology as gate lengths are scaled further.