Belgian nanotechnology research centre imec, along with Ghent University, has created arrays of indium phosphide lasers integrated monolithically on 300mm silicon substrates in a CMOS pilot line. The achievement is said to provide a path toward high volume manufacturing of cost effective photonic integrated circuits with monolithically integrated laser sources. The approach could help to speed data transfer between future logic and memory chips.
Widespread adoption of silicon photonics has been hampered, says imec, by the lack of monolithically integrated laser sources. One reason is the large mismatch in crystal lattice constants between both materials. The partners say they have overcome these structural differences and ‘largely suppressed’ the crystal defects that typically form at the interface between silicon and InP.
Using a production grade metal organic vapour phase epitaxial growth reactor, the partners were able to grow InP selectively on silicon in a pre patterned oxide template. This allowed InP waveguide arrays to be formed across the whole of the 300mm substrate. Grating structures etched in the top layer of these waveguides provide the optical feedback required for laser operation.
Typical lasing threshold powers of around 20mW were observed at room temperature under optical pumping, with small variability along the array. In addition, say the partners, accurate control on the distribution of lasing wavelengths in the array was demonstrated by modifying the grating parameters.
Author
Graham Pitcher
Source: www.newelectronics.co.uk