Temperature dependence of gate currents in thin Ta2O5 and TiO2 films

This letter reports our study of the temperature dependence of gate currents in thin Ta2O5 and TiO2 films. The study was conducted (1) to study the conduction mechanisms and band alignments, and (2) to determine whether the gate leakage current is tolerable at high temperatures for either of these high-dielectric-constant (high-k) oxides. The I–V characteristics of these oxides were measured and analyzed over a wide temperature range from 25 to 400 °C. Currents in Ta2O5 samples exhibited stronger temperature dependence than those in TiO2 samples, especially at high fields, mainly due to a much smaller electron barrier height of Ta2O5 over Si (0.28 eV) than that of TiO2 over Si (0.9 eV).