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This chapter systematically explores the fundamental properties, growth challenges, and application potential of aluminum nitride (AlN) single crystals. AlN and its alloy AlGaN exhibit a wide bandgap (200–365 nm) and exceptional physical properties—such as high thermal conductivity (340 W/m·K), breakdown field strength (12 MV/cm2), and radiation tolerance—which make them ideal for UV optoelectronics, high-power devices, and smart grid systems. However, the synthesis of large-sized and high-quality AlN single crystals remains technically challenging due to its high bond energy, lattice mismatch issues in heteroepitaxy, and limitations in current growth methods (PVT, HVPE, MOCVD). Among these methods, PVT achieves high growth rates and low dislocation densities but struggles with impurity control and cost-effectiveness; HVPE excels in film uniformity but faces dislocation density and substrate detachment hurdles; MOCVD dominates device fabrication but relies on heteroepitaxy due to substrate scarcity. The chapter also highlights AlN’s unique piezoelectric and acoustic properties, supported by its hexagonal wurtzite structure and spontaneous polarization, which enable applications in GHz-level FBAR devices. Optical anisotropy in AlN-based LEDs is attributed to its band structure and crystal field splitting, while comparative analyses with Si, SiC, and GaN underscore AlN’s advantages in high-voltage and UV-related technologies. Despite progress, challenges in device scalability, doping, and light extraction persist, necessitating further research for industrialization.

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Basic Properties of AlN Single Crystal

  • 章节

  • 发表日期：

    2025年

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  • Ke Xu,
  • Jun Huang

摘要

This chapter systematically explores the fundamental properties, growth challenges, and application potential of aluminum nitride (AlN) single crystals. AlN and its alloy AlGaN exhibit a wide bandgap (200–365 nm) and exceptional physical properties—such as high thermal conductivity (340 W/m·K), breakdown field strength (12 MV/cm2), and radiation tolerance—which make them ideal for UV optoelectronics, high-power devices, and smart grid systems. However, the synthesis of large-sized and high-quality AlN single crystals remains technically challenging due to its high bond energy, lattice mismatch issues in heteroepitaxy, and limitations in current growth methods (PVT, HVPE, MOCVD). Among these methods, PVT achieves high growth rates and low dislocation densities but struggles with impurity control and cost-effectiveness; HVPE excels in film uniformity but faces dislocation density and substrate detachment hurdles; MOCVD dominates device fabrication but relies on heteroepitaxy due to substrate scarcity. The chapter also highlights AlN’s unique piezoelectric and acoustic properties, supported by its hexagonal wurtzite structure and spontaneous polarization, which enable applications in GHz-level FBAR devices. Optical anisotropy in AlN-based LEDs is attributed to its band structure and crystal field splitting, while comparative analyses with Si, SiC, and GaN underscore AlN’s advantages in high-voltage and UV-related technologies. Despite progress, challenges in device scalability, doping, and light extraction persist, necessitating further research for industrialization.