Preparation and characterization of rare earth scandates as alternative gate oxide materials

Ternary oxides (GdScO3, DyScO3 and LaScO3—in general REScO3 whereas RE stands for rare earth) were studied as alternative high-κ-dielectrics. Thin amorphous films were deposited on Si (1 0 0) using pulsed laser deposition (PLD) with two different geometries (on-axis and off-axis). The films were characterized using Rutherford backscattering spectrometry (RBS), XRD, AFM, SEM and capacitors by CV and leakage current measurements. GdScO3 and DyScO3 remain in the amorphous phase while heating up to 1000 °C. The films produced in the on-axis-geometry are of higher quality concerning stoichiometry, morphology and electrical properties than the off-axis films. A composition close to the stoichiometry of REScO3 is found. In summary, a film density of 95% of crystalline samples, a surface roughness of about 1 Å RMS, a permittivity of about 20 and leakage current densities of 10−8 A/cm2 for a film thickness of 5 nm were achieved.