This study examined the performance and reliability of HfO2 gate dielectrics in p-type metal-oxide-semiconductor field effect transistors (pMOSFETs) capped with Al or Al2O3. The presence of Al capping deteriorated the pMOSFET scalability and channel mobility compared to Al2O3 capping. Al capping caused a higher rate of Al diffusion in the HfO2 dielectric layer, reducing the device performance and oxide thickness scaling. This degradation of the negative bias temperature instability of the Al-incorporated sample was attributed to decay of the interface quality rather than to a decrease in charge trapping in the bulk high-k dielectric. (C) 2012 Elsevier B.V. All rights reserved.