Transmission electron microscopy studies on structure and defectsin crystalline yttria and lanthanum oxide thin films grown on singlecrystal sapphire by molecular beam synthesis

摘要

he Molecular beam synthesis and characterization are reported for Y203thin films grown on Al203 (0001) substrate. The Y203 layer was highlyoriented in the [111] direction with predominant orientation relations (111)Y70311(0001) Al203 and [110] Y203[2110] Al203, corresponding to alattice mismatch of —20% at the interface. No significant interfacial layerswere found at the Y203/Al203 interface and the large lattice misfit wasaccommodated by formation of stacking faults, dislocations and secondaryorientation in the Y203 layer. A La203 interlayer improved the quality ofthe Y203 films. Full width at half maximum (FWHM) of the Y203 (222)peak decreased from 3.12° to 1.43° and the defect density in the Y203 layerwas significantly reduced. These results may be relevant in the broadercontext of designing oxide heterolayers with controlled microstructures.