Growth and characterization of LiGaO_2 substrate crystal for GaN epitaxy

摘要

We report Czochralski growth of LiGaO_2 single crystals, which are promising substrate materials for the epitaxy of GaN since the lattice mismatch between LiGaO_2 and GaN is only 0.9%. The dislocation etching pits morphologies and distribution characteristics were well revealed by chemical etching technique. Transmission electron microscopy (TEM) observations showed that γ-Ga_2O_3 inclusions tended to emerge in LiGaO_2 crystals owing to the volatilization of Li_2O during growth process. Therefore, many edged dislocations were induced, which usually lie on (001) plane. The amount of γ-Ga_2O_3 inclusions is closely related to growth parameters. X-ray topography shows that an interface parallel to (001) tends to form in the LiGaO_2 crystals pulled along (100). The two parts aside the (001) interface were slightly rotated around the interface normal. The crystal quality can be improved by using starting materials with excess of Li_2CO_3 and adopting appropriate growth parameters.