We report detailed charge trapping reliability characteristics of ultrathin ZrO2 and HfO2 dielectrics grown by the ultraviolet ozone oxidation (UVO) method. We also discuss the dependence of charge trapping on the top electrode deposition process, specifically in situ versus ex situ processed gates. Electrical data show that the charge trapping characteristics depend on the deposition method for the top electrode, likely due to exposure of the high-k material to ambient prior to deposition of the electrode. It is also shown that C–V hysteresis is not a complete measure of the charge trapping characteristics of the dielectrics. © 2004 American Institute of Physics.