Growth and characterization of (La,Sr)(Al,Ta)O-3 single crystals: a promising substrate for GaN epitaxial growth

摘要

Experimental results on the growth and characterization of single crystals of mixed perovskite (La,Sr)(Al,Ta)O-3 (LSAT), a promising material to prepare substrates for GaN epitaxial layers, growth by the Czochralski method, are reported. The single crystals obtained along < 111 > orientation up to 20 min in diameter and 50 mm in length were free of inclusions and macroscopic defects. The optical transmission was measured in the region 200 nm- 3000 mn. For the of < 111 > oriented LSAT single crystals, its measured unit cell parameter (a = 7,730 Angstrom) matches well to the GaN lattice. The chemical composition was checked by electron microprobe analysis. It was found that it is close to the stoichiometric one. With Lang transmission topography growth striations and dislocations were examined. Data on Vickers microhardness, thermal expansion coefficient, etch pit density and temperature dependence of electrical conductivity and capacitance are reported. [References: 12]