Porosity-controlled multilayer TaC coatings prepared via wet powder process for multi-functional reactor components in GaN crystal growth system

Abstract

Multilayer TaC coatings with layers of different porosities, that provide corrosion resistance and controlled wettability against molten metal are prepared via a wet powder process and a subsequent sintering process. A porous TaC top layer with a dense TaC underlayer formed on a graphite substrate is applied as a reactor component. It is found that this layer significantly increases the surface area of a molten Ga source via capillary action due to its high open porosity. It is also demonstrated that this layer enhances the Ga vapor supply rate, and thus the growth rate, during halogen-free vapor-phase epitaxial growth of GaN crystals.