High-Pressure, High-Temperature Solution Growth and Ammonothermal Synthesis of Gallium Nitride Crystals

Abstract In this chapter, two high-pressure growth methods for gallium nitride are described: growth from gallium solution under high nitrogen pressure and the ammonothermal technique. The chapter starts with a description of high nitrogen pressure solution (HNPS) growth. Some basics of this method, along with thermodynamic and kinetic aspects, are presented. Spontaneously grown gallium nitride (GaN) platelets and needles are characterized. Results obtained from the liquid phase epitaxy (LPE) technique as well as from a new approach to seeded growth, multifeed seed (MFS) configuration, are shown. The second part of this chapter deals with the ammonothermal technique to crystallize bulk GaN. After a brief review on the historical development of the method, chemistry of the solution, solubility, growth rates, and issues in doping in-situ are discussed. Properties of ammonothermal GaN are shown and an outlook on the prospects of the ammonothermal crystal growth technology is presented.