Impact of ultrathin Al2O3 barrier layer on electrical properties of LaLuO3 metal-oxide-semiconductor devices

Abstract

Temperature-dependent current-voltage measurements showed Poole–Frenkel conduction behavior through high-κ LaLuO3 films made by atomic layer deposition on Si. The energy levels that trap electrons were around 0.66 eV below the conduction band and were identified as oxygen vacancy levels. Oxygen treatments were done to decrease oxygen vacancies but an interfacial layer formed and the interface state density (Dit) increased. Therefore, ultrathin Al2O3 was used to protect the interface during oxygen treatments. Electrical properties were improved and no interfacial layer developed. Dit was below 9×1011 eV−1 cm−2 and leakage was 5×10−4 A/cm2 at 1 V for 1 nm equivalent oxide thickness.