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

Ternary oxides (GdScO 3 , DyScO 3 and LaScO 3 —in general RE ScO 3 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. GdScO 3 and DyScO 3 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 RE ScO 3 is found. In summary, a film density of 95% of crystalline samples, a surface roughness of about 1 A RMS, a permittivity of about 20 and leakage current densities of 10 −8 A/cm 2 for a film thickness of 5 nm were achieved.