Comparative Study of Si3N4-PECVD and Al2O3-ALD Surface Passivation in T-Shaped Gate InAlAs/InGaAs InP Based HEMTs

摘要

Surface passivation has a great impact on the DC and RF performance of HEMTs. In this paper, a comparative study of the DC and RF performance of InAlAs/InGaAs InP HEMTs (with L-g = 100 nm), passivated by Si3N4-PECVD and Al2O3-ALD has been presented. Increase in C-gd and C-gs is significantly limited. After passivation, an increase in g(m.MAX) up to 1160 mS/mm and 1150 mS/mm is observed in both cases. Improvement in the RF performance in case of Si3N4-PECVD is more obvious than Al2O3-ALD. In addition, a small-signal equivalent circuit model has been developed. It provides excellent agreement between measured and simulated results.