Czochralski growth and defect study of (La,Sr)(Al,Ta)O3 single crystals

The (La,Sr)(Al,Ta)O3 crystals, the potential substrate for GaN epitaxial layers were successfully grown by the Czochralski pulling method. The colors of the crystals will change with the growth atmosphere. One crystal shows a spiral growth due to the change of the melt composition. The structure was identified as a cubic by X-ray diffraction analysis. The optical transmission was measured with the wavelength range 250–3000 nm, and no obvious absorption peak was observed. The defect analyses were performed by using chemical etching and electron microscope. Besides, the results of high-angle X-ray spectrums indicated that the (La,Sr)(Al,Ta)O3 crystals have the second phase. Transmission electron microscope proved the second phase has an amorphous structure.