Aspect Ratio Impact on RF and DC Performance of State-of-the-Art Short-Channel GaN and InGaAs HEMTs

We report a comparison between state-of-the-art GaN and InGaAs HEMTs in terms of the minimum aspect ratio required to limit short-channel effects. DC and RF simulations were carried out through our full-band cellular Monte Carlo simulator, which includes the full details of the band structure and the phonon spectra. Our results indicate that the minimum aspect ratio for GaN devices is 15 for negligible short-channel effects and 10 for reduced short-channel effects. On the other hand, InGaAs devices perform well for lower aspect ratio values such as 7.5 and 4-5 for negligible and reduced effects, respectively. The origin of this difference between GaN and InGaAs HEMTs is believed to be related to the different dielectric constants of the two materials and the corresponding difference in the electric field distributions related to short-channel effects.