A novel liquid-phase epitaxy technique was developed that used a Ga-Al flux to grow AlN layers on nitrided sapphire substrates. Here, cross-sectional and plan-view images were taken using a transmission electron microscope. An edge dislocation was dominant in the liquid-phase epitaxial AlN layers; its density was approximately 5 x 109/cm2. Convergent-beam electron diffraction analysis revealed that the liquid-phase epitaxial layer had Al polarity, even though the nitrided sapphire layer had N polarity. The oxygen potential in the injecting N2 gas played an important role in the polarity inversion in the liquid-phase epitaxial growth.

Analysis of the Dislocation and Polarity in an AlN Layer Grown Using Ga-Al Flux. M.Adachi, M.Takasugi, D.Morikawa, K.Tsuda, A.Tanaka, H.Fukuyama: Applied Physics Express, 2012, 5[10], 101001