Hybrid integration of GaAs-based quantum cascade lasers and silicon technology
The integration of Si- and III-V based devices into single chips has recently been investigated extensively. In particular this will encourage further development
of information and communication technologies due to integration of infrared optoelectronic devices with well established Si technology.
We show the integration of Si and GaAs quantum cascade lasers by Au-Au thermo-compression bonding. Titanium/gold layers were used as an
intermediate cohesion layer between the GaAs laser chip and the Si substrate. The III-V heterostructure was bonded epilayer down onto the patterned Si substrate.
Due to the fact that gold has the lowest thermal resistivity of all metals and alloys used typically for epi-down mounting, heat extraction
from the active region of the laser is increased. Furthermore, this epi-down approach makes the use of extended contacts on the III-V chip obsolete.
This decreases the number of lithographic steps necessary and makes it easier to contact very narrow ridges (< 5μm).
Illustration of the hybrid integration of QCLs and Si-technology