Tuning the interlayer microstructure and residual stress of buffer-free direct bonding GaN/Si heterostructures

The direct integration of GaN with Si can boost great potential for low-cost, large-scale, and high-power device applications. However, it is still challengeable to directly grow on without using thick strain relief buffer layers due their large lattice thermal-expansion-coefficient mismatches. In this work, a GaN/Si heterointerface any layer successfully fabricated at room temperature via surface activated bonding (SAB). residual stress states interfacial microstructures heterostructures were systematically investigated through micro-Raman spectroscopy transmission electron microscopy. Compared the compressive that existed in grown-on-Si by MOCVD, significantly relaxed uniform small tensile was observed bonded-to-Si SAB; mainly ascribed amorphous formed interface. addition, microstructure bonded heterointerfaces found be tuned appropriate thermal annealing. This work moves an important step forward integrating present CMOS technology high quality thin interfaces, brings promises wafer-scale low-cost fabrication electronics.