Stress relaxation in GaN by transfer bonding on Si substrates

The stress state of GaN epilayers transferred onto Si substrates through a Au-Si bonding process was studied by micro-Raman scattering and photoluminescence techniques. By increasing the Au bonding thickness from 1 to 40 μm, the high compressive stress state in GaN layer was relieved. A 10 μm Au bonding layer thickness is shown to possess the maximum compressive stress relief and also the deformation potential of the quantum well was found to be ∼85 meV. A nonlinear parabolic relation between luminescent bandgap and the biaxial stress of the transferred GaN epilayer in the compressive region was observed.