Analysis of thermal stress in wafer bonding of dissimilar materials for the introduction of an InP-based light emitter into a GaAs-based three-dimensional photonic crystal

Thermal stresses generated by differences in the thermal expansion coefficients of InP and GaAs are analyzed in an attempt to introduce an InP-based light emitter into GaAs-based three-dimensional photonic crystal. Observations of the GaAs/InGaAsP bonding interface by scanning acoustic microscopy reveal that debonding occurs at approximately 300 °C due to thermal stress. Calculations of thermal stress by a two-dimensional finite element method suggested that thermal stress could be reduced by thinning the substrate, which was confirmed experimentally. Using these results, a three-dimensional photonic crystal with light emitter was successfully fabricated.