Recently, China-based Ziener Tech has unveiled progress in sapphire substrate thinning, announcing that it has successfully reduced the substrate thickness of its 8-inch GaN-on-sapphire wafers to 50μm. In practical applications, heat dissipation has long been a key bottleneck limiting GaN device performance. Substrate material plays a critical role in thermal management. Sapphire offers strong insulation, high thermal stability, and relatively good lattice and thermal matching with GaN, enabling simpler epitaxial structures. However, its inherently low thermal conducti...