Imec integrates lasers into silicon wafers for photonics

Together with researchers from Ghent University, imec has developed a method for integrating lasers on silicon wafers. This would make the production of silicon photonics, a combination of optical communication and transistor technology, simpler and cheaper.

It is very difficult to integrate semiconductors suitable for lasers on the same silicon substrate that is used for semiconductors for processors, among other things. The crystal structure of laser semiconductors does not match that of the silicon, requiring additional steps to first apply a compatibility layer. Researchers from imec, an international research center that is active in Leuven, among other places, have developed a method together with researchers from Ghent University to simplify this process.

They used silicon wafers with a silicon oxide pattern on which the laser semiconductor material could ‘grow’. That semiconductor material, indium phosphide, was applied as a vapor with the pre-etched pattern serving as a hold. Grids were etched into the waveguides of the indium phosphide for the lasing. By varying the grids, the wavelength of the lasers could be adjusted and during tests the lasers appeared to function uniformly. In this way, InP lasers were built on an entire 300mm silicon wafer using standard cmos manufacturing methods.

The research would pave the way for large-scale and low-cost production of lasers on silicon wafers. Such lasers can then be combined with cmos structures such as processors or signal processors, so that the lasers are operated directly with electrical pulses. With this, optical chips could be realized, so that optical data communication can proceed faster and can even be communicated within computers with optical instead of electrical signals.