Research Progress in Liquid Phase Growth of GaN Crystals

As a wide band gap semiconductor, gallium nitride (GaN) has high breakdown voltage, excellent structural stability and mechanical properties, giving it unique advantages in applications such as high frequency, high power, and high temperature. As a result, it has broad application prospects in optoelectronics and microelectronics. However, the lack of high-quality, large-size GaN crystal substrates severely limit the improvement of electronic device performance. To solve this problem, liquid phase growth of GaN has attracted much attention because it can produce higher quality GaN crystals compared to traditional vapor phase growth methods. This review introduces two main methods of liquid phase growth of GaN: the flux method and ammonothermal method, as well as their advantages and challenges. It reviews the research history and recent advances of these two methods, including the effects of different solvents and mineralizers on the growth quality and performance of GaN crystals, as well as various technical improvements. This review aims to outline the principles, characteristics, and development trends of liquid phase growth of GaN, to provide more inspiration for future research on liquid phase growth, and to achieve further breakthroughs in its development and commercial application. The flux and ammonothermal methods are capable of the growth of large size, high quality GaN crystals, which are the main methods of liquid phase growth. The research progress of these two growth methods in terms of chemical additives and growth process is summarised, and their application prospects in industrial production are discussed.image