ABSTRACT
The sequence of the operations influences significantly the form of the GaN polycrystalline layer on gallium surface which is the first step of GaN synthesis in considered process. The surface layer consists of GaN single crystals the size of which depends upon the sequence of compression and heating. If the compression is performed after heating, the crystals at surface are relatively big since they grow at low super-saturation. The observation of the crystal morphology allows to conclude that dominating growth mechanism especially for higher rates is two dimensional layer growths with nucleation at the edges exposed to the growth solution. Such a mechanism suggests relatively high local super saturations and expresses a tendency to lose a stability of the growing face with further increase of growth rate. Further optimization of both substrate and homoepitaxial growth techniques should lead to the fabrication of efficient optoelectronic devices. Special effort has to be paid on increasing of the size of high quality GaN substrates.
