Synergistic crucible design and thermal-flow management for enhanced 4-inch AlN single crystal PVT growth: a combined numerical and experimental investigation

Abstract

High-quality, large-diameter aluminum nitride (AlN) single crystals are essential for advanced electronic and optoelectronic applications. However, their physical vapor transport (PVT) growth remains challenging due to complex thermal-flow dynamics and crucible design limitations. In this study, we comprehensively investigate the synergistic optimization of crucible geometry and thermal-flow management on a VR-PVT crystal growth platform. Numerical simulations reveal that positioning the seed crystal at 35–45% of the main heater's height stabilizes the growth rate, while refined crucible design and optimized vapor pathways ensure a uniform thermal-flow field for sustained growth. Experimental validation demonstrates the efficacy of our approach by producing AlN ingots exceeding 4 inches in diameter. X-ray diffraction (XRD) analysis shows that the full width at half maximum (FWHM) of the rocking curve for the (0002) plane ranges from 277 to 446 arcsec. Raman spectroscopy further indicates that the FWHM of the E₂ (high) phonon mode falls between 7.41 and 7.62 cm⁻¹. Both measurements confirm that the synthesized AlN crystal exhibits good uniformity. These results provide valuable process insights and establish a scalable framework for PVT-based synthesis of high-quality AlN single crystals.