Stress Adjustment and Bonding of H-Implanted 2 in. Freestanding GaN Wafer: The Concept of Double-Sided Splitting

Heterointegration of thin layers obtained from freestanding GaN wafers by the Smart-Cut process faces major challenges due to strong wafer bowing. The post-implantation bow was found to range between similar to 40 and 60 mu m for 2 in. wafers, prohibiting any bonding of H-implanted GaN. Here, we demonstrate that stress engineering by back-side implantation is an effective strategy to manipulate the bow to meet the criterion of long-range flatness. Based on our approach, high-quality bonding of a 2 in. freestanding GaN wafer onto sapphire was achieved. An efficient method to transfer thin layers from freestanding GaN is proposed.