16. Properties of Ammonothermal Crystals

The chapter delves into the properties of ammonothermal crystals, highlighting the importance of GaN for various optical, optoelectronic, and electronic devices. It discusses the ammonothermal growth method, which is superior for producing high-quality GaN substrates. The structural properties of GaN, including its lattice parameters and defects, are examined in detail. The chapter also explores the challenges in reducing oxygen concentration and the implications for device performance. Additionally, it covers the thermal properties of GaN and the successful deposition of high-quality epitaxial films on ammonothermal substrates. The chapter concludes with a discussion on the potential applications of ammonothermal GaN in high-power and high-frequency devices, emphasizing the need for further improvement in substrate quality.