【凝聚态物理-北京大学论坛2023年第21期(总573期)】Recent progress and prospects on bulk AlN crystal growth by PVT method
Bulk AlN offers excellent properties, wide bandgap (6.2 eV), high thermal conductivity [340 w/(m·°C)], high breakdown field strength (15.4 MV/cm), and chemical stability, consequently shows compelling advantages over SiC/GaN/Ga2O3 in power electronics as well as in deep-UV optoelectronics. In the past decades, considerable effort has been made to grow bulk AlN crystals. Nevertheless, growing large high-quality AlN single crystals is still a very challenging task. In this talk, general strategies to grow AlN crystals by physical vapor transport（PVT）method will be given and their advantages and disadvantages will be addressed in great detail. Finally crack-free and high-quality AlN single crystalline boules up to 76 mm (3 inches) in diameter by the homoepitaxial PVT method using a serials of proprietary techniques will be demonstrated. Material characterization results by HRXRD, Raman spectroscopy and preferential chemical etching after standard lapping/polishing will also be presented. At the end of this talk, primary Far-UVC LED (232 nm) and surface acoustic wave (SAW) devices based on C-plane and A-plane bulk AlN substrates will also be demonstrated, respectively.