GROWTH OF III-NITRIDES ON ZNO, LIGAO2, AND LIALO2 SUBSTRATES

The use of oxide substrates for growth of III-nitride materials has be en investigated. ZnO did not produce any improvement in InAln or AlN m aterial quality over that obtained using optimized growth conditions o n sapphire or GaAs. This is believed to be due to the poor thermal sta bility of ZnO and to the absence of the formation of a nitride layer a t the substrate surface which acts as both a protective layer and as a n aid to nucleation. The poor thermal stability of the ZnO prevented t he use of a pre-growth plasma anneal. Such an anneal was found to prod uce significant improvement in the surface morphology and structural q uality of AlN grown on sapphire. Though (100) LiGaO2 and (100) LiAlO2 exhibited greater thermal stability, preliminary experiments on growth of GaN on LiGaO2 and InN on LiAlO2 suggest that, as for sapphire, low temperature buffers may be required to improve nucleation behavior.