BAND ALIGNMENT AND ATOM SEGREGATION OF LaYbO3 FILMS ON SILICON

Abstract

Ternary rare earth oxides are expected to be more promising high-k dielectric materials than conventional binary rare earth oxides due to higher band gap, higher permittivity and good interfacial stability. In the present study, the band alignment and atom thermal diffusion of LaYbO3 , a new ternary rare earth oxide, are studied by X-ray photoelectron spectrum (XPS) and angle-resolved XPS, respectively. The band gap value for LaYbO3 crystalline film rises to 6.7 eV compared with 6.2 eV for amorphous film. Valence (ΔEv) and conduction band (ΔEc) offset are ΔEv = 3.5 eV, ΔEc = 1.6 eV for the amorphous film and ΔEv = 3.3 eV, ΔEc = 2.3 eV for the crystalline film. From elemental depth profile through high-k layer and silicon substrate, it is shown that La atom tends to diffuse into silicon substrate and piles up at oxide/silicon interface at high annealing temperature ~1000°C.