DIELECTRIC AND INTERFACE STABILITY OF LaSmO3 FILMS

Abstract

The continuous downscaling of metal oxide semiconductor field effect 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 film, LaSmO3 , is deposited using electron-beam evaporation. The structure and high temperature interfacial thermal stabilities are investigated by X-ray diffraction (XRD), X-ray photon electronic spectra (XPS), infrared attenuated total reflection (ATR) and time of flight second ion mass spectroscopy (ToF-SIMS). The band gap and band offset are determined using the O 1s energy loss spectra and valence band difference between film 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 LaSmO3 is >1000°C. The high dielectric constant (k) = 24.6, large band gap (Eg) > 7 eV and low leakage current (1.8 × 10-4 A/cm2, 1 MV/cm) make LaSmO3 to be a promising high-k candidate.