Improved oxide passivation of AlGaN/GaN high electron mobility transistors

saturation current in HENTs had increases of 4.5% and 1%, respectively, for Mg0.5Ca0.5O and Mg0.25Ca0.75O passivated devices. However, there was a 10% decrease for the device passivated with pure MgO. This was due to strain applied on the nitride HEMT by the oxide, which is consistent with the piezoelectric effect in the nitride HEMT by the oxide, which is consistent with the piezoelectric effect in the nitride form the lattice mismatch between AlGaN and GaN. From pulsed measurements, HEMTs passivated with Mg0.5Ca0.5O and Mg0.25Ca0.75O showed higher passivation effectiveness 90% of dc current then the MgO passivated HEMTs 83% dc current. This is due to the closer lattice matching of these calcium containing oxides and the reduction in interface traps associated with lattice mismatch. © 2005 American Institute of Physics. DOI: 10.1063/1.2105987