Structural and electrical properties of HfLaOx films for an amorphous high-k gate insulator

Abstract

Thin HfLaOx films on Si(100) have been investigated as an alternative gate insulator. The introduction of La2O3 into HfO2 causes an increase of crystallization temperature. Furthermore, unlike other Hf-based amorphous materials such as HfSiOx or HfAlOx, the permittivity of HfLaOx keeps a high value (>20). The capacitance-voltage curve of metal oxide semiconductor capacitor using the HfLaOx dielectric film has shown a negligible hysteresis and no frequency dispersion, indicating very small degradations of both interface and bulk properties. In addition, a very low fixed charge density in HfLaOx films is demonstrated from a very small film thickness dependence of the flatband voltage.