Effect of High-Temperature Nitridation and Buffer Layer on Semi-Polar (10-13) AlN Grown on Sapphire by HVPE

We have investigated the effect of high-temperature nitridation and buffer layer on the semi-polar aluminum nitride (AlN) films grown on sapphire by hydride vapor phase epitaxy (HVPE). It is found the high-temperature nitridation and buffer layer at 1300 °C are favorable for the formation of single (10-13) AlN film. Furthermore, the compressive stress of the (10-13) single-oriented AlN film is smaller than polycrystalline samples which have the low-temperature nitridation layer and buffer layer. On the one hand, the improvement of (10-13) AlN crystalline quality is possibly due to the high-temperature nitridation that promotes the coalescence of crystal grains. On the other hand, as the temperature of nitridation and buffer layer increases, the contents of N-Al-O and Al-O bonds in the AlN film are significantly reduced, resulting in an increase in the proportion of Al-N bonds.