Growth of Bulk Gallium Nitride Single Crystal by Sodium Flux Method: A Brief Review

Growing interest in homoepitaxial growth of nitride-based devices has driven considerable efforts towards producing bulk gallium nitride single crystal as a substrate for the devices. Therefore, the process of producing the bulk gallium nitride crystal substrate should be simple and yet cost-effective to reduce the production cost of the devices. To date, several methods of growing bulk gallium nitride crystal have been proposed. Sodium flux method is one of the most promising ways since it requires a moderate growth temperature and growth pressure, as well as being simple and costeffective. This paper will briefly review the progress made to advance the growth of bulk gallium nitride single crystal by sodium flux method, including discussing challenges and proposing possible improvements in future.