Lasers on silicon: Low temperature heterogeneous integration without glue
Nobuhiko Nishiyama and colleagues at Tokyo Institute of Technology have demonstrated the operation of 1.55µm GaInAsP lasers on silicon using low temperature plasma activated bonding (PAB).
The hybrid wafers, which consist of an InP-based wafer and a SOI wafer, were fabricated by PAB. The two wafers were irradiated with plasma in a vacuum chamber to active the surface. Then, the two wafers were bonded at 150degC, which is much lower than that of conventional bonding methods. Even at such low temperature bonding, the wafers had sufficient bonding strength, according to the researchers.
The hybrid lasers showed lasing operation at room temperature. The threshold current was 64mA, which corresponds to a threshold current density of 850A/cm2.
The team believes that such hybrid lasers could be a key technology for future large scale photonic platforms such as single-chip optical routers, interconnection for big data transmission, and even artificial intelligence technology.
"˜Low Threshold Current Density Operation of a GaInAsP/Si Hybrid Laser Prepared by Low-Temperature N2 Plasma Activated Bonding' by Yusuke Hayashi et al; Japanese Journal of Applied Physics, 52, 060202 (2013).
