Vertical-cavity surface-emitting laser chip bonding by surface-tension-driven self-assembly for optoelectronic heterogeneous integration

Twelve-channel vertical-cavity surface-emitting laser (12-ch VCSEL) chips are heterogeneously self-assembled on Si and glass wafers using water surface tension as a driving force. The VCSEL chips have a high length-to-width aspect ratio, that is, 3 mm long and 0.35 mm wide. The VCSEL chips are precisely self-assembled with alignment accuracies within 2 µm even when they are manually placed on liquid droplets provided on the host substrate. After the self-assembly of the VCSEL chips and the subsequent thermal compression, the chips successfully emit 850 nm light and exhibit no degradation of their current–voltage (I–V) characteristics.