The influence of the PCF scattering on the electrical properties of the AlGaN/AlN/GaN HEMTs after the Si 3 N 4 surface passivation

In this paper, the detailed device characteristics were investigated both before and after the Si 3 N 4 passivation grown by plasma-enhanced chemical vapor deposition (PECVD). Better transport properties have been observed for the passivated devices compared with the same ones before passivation. The strain variation and the influence of the scattering mechanisms were analyzed and studied. The calculated results show that the non-uniform distribution of the additional polarization charges at the AlGaN/AlN/GaN interfaces has been weakened by the deposition of the Si 3 N 4 layer. The numerical rise of the two-dimensional electron gas (2DEG) electron mobility and the decrease of the measured R on – A values were in a good consistency, and the weakening of the polarization Coulomb field (PCF) scattering after the passivation process is considered to be the main cause of these phenomena.