Optimization of Growth Temperature and V/III Ratio toward High-Quality Si-Doped Aluminum Nitride Thin Films on Sapphire

Ultrawide-band-gap aluminum nitride (AlN) boasts high breakdown field strength, superior thermal conductivity, and exceptional stability, making it ideal for deep ultraviolet optoelectronics, radio frequency, and power devices. To date, the epitaxial growth of high-quality doped AlN via MOCVD has primarily been on AlN or SiC single-crystal substrates to reduce dislocation densities. However, the limited size and high cost of these single-crystal substrates necessitate the exploration of alternative substrates to enhance commercial viability. This study demonstrates and analyzes the epitaxial growth modes and conductivity modulation mechanisms of AlN:Si on a cost-effective sapphire substrate. By adjusting MOCVD epitaxial parameters: growth temperature and V/III ratio, we controlled the impact of compensating defects (CN and VAl) on conductivity, achieving conductivity enhancements of 26 and 41%, respectively. Our research validates the feasibility of obtaining AlN:Si with enhanced electrical performance and crystal quality on sapphire substrates. It represents a significant step toward the development of high-power, high-efficiency AlN electronic devices.