Parametric investigation of laser diode bonding using eutectic AuSn solder

Based on an optimized bonding technique for semiconductor lasers, parametric investigations of different bonding configurations were performed using AuSn solder. No abrupt electrical degradation was observed for both face-up and face-down bonding configurations. The typical optical output achieved for face-up and face-down bonding approach was about 100 mW/facet and 150 mW/facet, respectively. Face-up bonded LDs exhibited a steady differential quantum efficiency ηD of ∼ 0.425 mW/mA before gradual degradation at 200 mA, while face-down bonded LDs improved its performance beyond 350 mA. The characteristic temperature T0 also improved to as much as 643 K for face-down bonded LDs. Spectrally-resolved emission measurement showed that the temperature rise in unbonded, face-up bonded and face-down bonded LDs were approximately 11, 7–8 and 2–3 °C, respectively. These investigations showed that the improved performances for face-down bonding approach compared to face-up approach were due to better thermal management.