Development of a New Solution Growth Method for AlN Single Crystals Using Type 430 Ferritic Stainless Steel Flux

The solution growth method is an economical and environmentally friendly approach to producing aluminum nitride (AlN) single crystals. However, the fluxes used in the solution growth method have low nitrogen solubility, which limits the growth rate of AlN. In this study, as part of the development of a solution growth method for AlN using Fe-Cr fluxes with high nitrogen solubility, experiments were conducted using type 430 ferritic stainless steel, which is composed mainly of Fe-Cr, as the flux. Through a series of experiments, we report the results of the optimization of various experimental growth parameters (AlN polarity, cooling rate, and growth temperature). Furthermore, a growth mechanism based on the Al:N ratio in the flux is proposed, introducing the concept of effective nitrogen content to explain how the growth temperature affects the AlN growth rate using Fe-Cr flux.