High temperature characterization of high-κ dielectrics on SiC

We have fabricated thin catalytic metal–insulator–silicon carbide based structure with palladium (Pd) gates using TiO₂ as the dielectric. The temperature stability of the capacitor is of critical importance for use in the fabrication of electronics for deployment in extreme environments. We have evaluated the response to temperatures in excess of 450 °C in air and observed that the characteristics are stable. Results of high temperature characterization are presented here with extraction of interface state density up to 650 °C. The results show that at temperatures below 400 °C the capacitors are stable, with a density of interface traps of approximately 6×10¹¹ cm² eV⁻¹. Above this temperature the C–V and G–V characteristics show the influence of a second set of traps, with a density around 1×10¹³ cm² eV⁻¹, which is close to that observed for slow states near the conduction band edge. The study of breakdown field as a function of temperature shows two distinct regions, below 300 °C where the breakdown voltage has a strong temperature dependence and above 300, where it is weaker. We hypothesize that the oxide layer dominates the breakdown voltage at low temperature and the TiO₂ layer above 300 °C. These results at high temperatures confirms the suitability of the Pd/TiO₂/SiO₂/SiC capacitor structure for stable operation in high temperature environments.