Investigation of As Grown and Induced Structural Defects in SrLaXO$\text{}_{4}$ (x = Al, Ga) Crystals

SrLaGaO$\text{}_{4}$ and SrLaAlO$\text{}_{4}$ substrates grown by the Czochralski method have no twins or subgrains however they show strong tendency to form point defects. The nature of these defects is not well understood yet. They may be associated with deviations from stoichiometry andor oxygen atoms located in the interstitial positions. Virtually all title crystals grown by the Czochralski method display various colours from light green to deeply red owing to light absorption by point defects. Absorption centres appear to be very stable in time and resistant to usual thermal treatment. UV excitation increases the density of defects and gives rise to strong photoluminescence, otherwise too weak to be observed