Realizing overgrowth in the homo-PVT process for 2 inch AlN single crystals

Abstract

In this paper, the growth and promotion of 2 inch AlN single crystals are carried out via the homogeneous physical vapor transport (PVT) method on AlN seeds. It is found that the large-size AlN crystal homo-PVT process is distinguished by the growth of prismatic grains in a macroscopic 3-dimensional mode, and overgrowth plays a key role in the merging of grains under a lateral overgrown c-plane surface. To realize efficient overgrowth, we study the control law of growth conditions through a combination of experiments and computational fluid dynamics (CFD) simulations, and clarify that the effect of overgrowth depends on growth rate and its matching relation with temperature and pressure. Our results show that overgrowth can obviously improve the coherence of c-plane orientations and crystal quality, which provides a foundation for quality promotion through iterative homo-PVT growth on large-size AlN seeds.