Four-inch high quality crack-free AlN layer grown on a high-temperature annealed AlN template by MOCVD

In this work, based on physical vapor deposition and high-temperature annealing(HTA), the 4-inch crack-free highquality AlN template is initialized. Benefiting from the crystal recrystallization during the HTA process, the FWHMs of X-ray rocking curves for(002) and(102) planes are encouragingly decreased to 62 and 282 arcsec, respectively. On such an AlN template,an ultra-thin AlN with a thickness of ～700 nm grown by MOCVD shows good quality, thus avoiding the epitaxial lateral overgrowth(ELOG) process in which 3–4 μm AlN is essential to obtain the flat surface and high crystalline quality. The 4-inch scaled wafer provides an avenue to match UVC-LED with the fabrication process of traditional GaN-based blue LED, therefore significantly improving yields and decreasing cost.