INFLUENCE OF PYROLYTIC BORON-NITRIDE CRUCIBLES ON GAAS CRYSTAL-GROWTHPROCESS AND CRYSTAL PROPERTIES

The influence of pyrolytic boron nitride (pBN) crucibles on the GaAs l iquid encapsulated Crochralski (LEC) growth process and on the crystal properties was investigated. An increased boron concentration in the crystals is found to be caused by oxidation processes between B2O3 . x H(2)O, GaAs and impurity elements in GaAs as a function of water conte nt and not by dissolution of boron from the crucible. Variations of pB N deposition parameters influence the texture and properties of pBN cr ucibles with regard to their suitability for the GaAs LEC crystal grow th application. Correlations between pBN morphologies and thermal cond itions of GaAs growth process and the crystal perfection were found. T he best results are obtained by using so-called substrate nucleated pB N crucibles.