Enhancement of effective dielectric constant using high-temperature mixed and sub-nano-laminated atomic layer deposited Y2O3/Al2O3 on GaAs(001)

Abstract

In-situ atomic layer deposition (ALD) Y2O3/Al2O3 in bi-layered and sub-nano-laminated structures were stacked on pristine GaAs(001) substrates for fabricating metal-oxide-semiconductor capacitors. The bi-layered Y2O3/Al2O3 showed an enhanced effective dielectric constant from 11.1 to 15.6 in capacitance-voltage characteristics with post deposition annealing to 900°C. No new oxide phase formed as carefully examined using synchrotron radiation X-ray diffraction and cross-sectional high-resolution scanning tunneling electron microscopy. We designed and grew sub-nano-laminated Y2O3/Al2O3 multi-layers to simulate the mixing of gate oxides, and observed an enhanced dielectric constant of 14.8 for the as-deposited sample. Both high-temperature mixed and sub-nano-laminated ALD Y2O3/Al2O3 exhibit high dielectric constant, low leakage current ~10−8A/cm2 and low interfacial trap density with GaAs(001), promising for high κ applications in future GaAs metal-oxide-semiconductor devices.