Tuning of electron affinity of high-k zirconia gate dielectrics for next-generation electronic devices

Abstract

A simple method based on the current-voltage (I-V) measurements is developed to estimate the Zirconia’s (ZrO₂) electron affinity. The estimated electron affinity of ZrO₂ is 2.86 eV, 2.85 eV, 3.07 eV, and 2.84 eV for the annealing temperatures of 400 °C, 500 °C, 600 °C, and 700 °C, respectively. The electron affinities are comparable to those deduced from the Ultraviolet Photoelectron Spectroscopy (UPS) and Internal photoemission measurements. The estimated electron affinity is used to draw the band alignment of ZrO₂-based MOS devices, which gives an insight into various conduction mechanisms across the ZrO₂. An important observation of our study is that the electron affinity of zirconia can be tuned by varying the annealing temperature. The method developed here may be generalized for the other high-k materials.