Low interface states and high dielectric constant y₂O ₃ films on Si substrates

Y₂O₃ films were deposited on c-Si substrates at temperatures in the 400-550°C range, with no further thermal treatment given to these samples, using the spray pyrolysis technique. The spraying solution was yttrium acetilacetonate disolved N,N-dimethylformamide. In addition, a solution of H₂O-NH₄OH was sprayed in parallel during the deposition process to improve the optical, structural, and electrical properties of the deposited films. The growth of a SiO₂ layer between the yttrium oxide and the Si substrate during this deposition process resulted in interface state density values as low as 10¹⁰ eV^-1 cm ^-2. An effective refractive index value of 1.86, and deposition rates close to 1 Å/s were obtained. The Y₂O₃ films were polycrystalline with a crystalline cubic phase highly textured with the (400) direction normal to the Si surface. An effective dielectric constant up to 13, as well as a dielectric strength of the order of 0.2 MV/cm was obtained for ∼1000 Å thick as-deposited films incorporated in a metal-oxide-semiconductor structure.