Low temperature bonding of epitaxial lift off devices with AuSn

The increasing demand for more advanced optoelectronic integrated circuits has created the need for bonding materials with different lattice constants (for example, GaAs on Si). In this paper, we report a new way for the bonding of epitaxial lift off (ELO) devices onto substrates. The multilayer structures investigated in this work produce a resulting AuSn alloy with approximately 84 wt.% gold, but can be bonded with a peak temperature of 235/spl deg/C. The bonded samples were investigated with several standard surface analysis techniques like optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX) as well as mechanical tests. The results of our research allowed us to optimize the layer structure, the bonding parameters as well as the diffusion barriers.