Charge detrapping in HfO_(2) high-k gate dielectric stacks

摘要

We investigated the kinetics of charge detrapping in high-k gate stacks fabricated with ultrathin HfO_(2) dielectric films grown by atomic layer deposition and a polycrystalline silicon gate electrode. It was observed that charge trapped after electron injection in the high-k stack was unstable and slowly decayed over time. The decay does not follow a simple first-order exponential law suggesting complex detrapping mechanism(s), possibly involving more than one type of trap present in the stack. The detrapping rate was found to depend strongly on gate voltage, temperature, and light illumination.