DIELECTRIC AND INTERFACE STABILITY OF LaSmO₃ FILMS

Abstract

The continuous downscaling of metal oxide semiconductor¯eld e®ect transistors (MOSFET) on silicon, germanium, GaAs, etc. still demands the creation of new high-k dielectrics with even better material performance. In this research, a new ternary high-k dielectric¯lm, LaSmO 3 , is deposited using electron-beam evaporation. The structure and high temperature interfacial thermal stabilities are investigated by X-ray di®raction (XRD), X-ray photon electronic spectra (XPS), infrared attenuated total re°ection (ATR) and time of°ight second ion mass spectroscopy (ToF-SIMS). The band gap and band o®set are determined using the O 1s energy loss spectra and valence band di®erence between¯lm and substrate, respectively, from the XPS spectra. Capacitance-voltage (CV) and current-voltage (IV) curves are measured to give an insight of the dielectric and leakage current of this material. It is found that crystallization temperature of LaSmO 3 is >1000 C. The high dielectric constant ðkÞ ¼ 24:6, large band gap ðE g Þ > 7 eV and low leakage current (1:8 Â 10 À4 A/cm 2 , 1 MV/cm) make LaSmO 3 to be a promising high-k candidate.