Effective work function of Pt, Pd, and Re on atomic layer deposited HfO2

Platinum and Pd show a significant difference in work function on SiO2 and high-K materials (HfO2). The effective metal work functions for Pd, Pt, and Re on atomic layer deposited HfO2, which are different from the vacuum work function and important for device threshold voltage control, are measured by the C-V method. The difference is attributed to the dipoles at the metal/HfO2 interface, which is a result of charge transfer across the interface. Moreover, the extracted charge neutrality level and screening parameter are correlated with the phase development, film stoichiometry, and density of interface states at the metal/high-K interface.