Polarization Engineering in AlSiO/p-type GaN MOSFETs Using AIN Interlayers Formed by Plasma-Enhanced Atomic Layer Deposition

Polarization engineering by AIN interlayers (AlN-ILs) deposited via plasma-enhanced atomic layer deposition was demonstrated in AlSiO/p-type GaN MOSFETs. Transmission electron microscopy observations revealed that the AlN-ILs were grown on GaN epitaxially and therefore could induce polarization charges, similar to AlGaN/GaN. The decrease in the threshold voltage (V
th
) with increasing AIN-IL thickness corresponded to the polarization charge density. In addition, insertion of the AIN-IL suppressed the positive bias instability by less than 0.05 V. By controlling the AIN-IL thickness and the channel p-type doping, we controlled the V
th
the range from −3 to 5 V and achieved enhanced channel mobility compared with that for the corresponding MOSFET without an AIN-IL.