BinOptics CEO hopes to sample GaN lasers in 2007
BinOptics, the Cornell University spin-out company that specializes in etched-facet lasers, has developed a continuous-wave 405 nm laser that has a much shorter cavity than current commercial designs.
If the technology can be fully developed and scaled to volume production, it could allow three times more lasers to be fabricated on a given wafer, and slash the cost of producing the individual devices.
BinOptics CEO Alex Behfar told compoundsemiconductor.net that a new etched-facet process technology designed specifically for GaN lasers was the key to the latest development. As well as enabling smaller laser chips, the method allows on-wafer device testing, which could also cut processing costs.
Using a standard chemically-assisted ion beam etching tool, specially adapted by the BinOptics team for GaN material, Behfar and colleagues were able to make continuously-emitting blue lasers with cavity lengths as short as 100 µm and threshold currents a low as 10 mA.
Emitting 5-10 mW (the power depending on the cavity size), the lasers should be powerful enough for high-definition DVD playback, and with on-wafer lifetimes of several hours already demonstrated, their initial reliability looks promising.
Conventional processing relies on cleaving the wafer to define the individual laser facets, or mirrors, and results in a typical die size of 400 µm by 600 µm.
At that die size, a 2-inch wafer yields a maximum of 5000 chips. But, using the etched-facet approach, and producing lasers with a cavity length of only 200 µm, would triple that potential yield to 15000 lasers.
If the etching process can be applied on a large scale, it could help to cut the cost of individual blue diodes dramatically. BinOptics is now working on laser singulation, packaging and assessing the lifetime of packaged devices, and is also looking at the possibility of making 200 µm x 200 µm lasers, something that would further double the potential device yield.
Like major manufacturers such as Sony, BinOptics is fabricating the lasers on expensive free-standing GaN substrates, of which Japan-based Sumitomo Electric Industries is the dominant supplier. The relatively small wafer diameters available and the number of defects in the GaN material system is hindering the drive to reduce the cost of the lasers through volume production, however.
"We need to complete the development [of the GaN lasers], and get our supply chain organized," Behfar said, adding: "I would be very disappointed if we couldn t begin to sample a small number of blue lasers later this year."
The CEO added that he remains open to a variety of strategies with which to move forward, including potential licensing deals with major chip manufacturers.
BinOptics obtains some of its epitaxial material from a partner in Japan currently, but hasn t ruled out the possibility of ramping up GaN wafer manufacturing at its own facility in the future.
"We are planning not to need another round of [venture] funding," Behfar said. "But if we decide to adopt a more aggressive approach, for example doing MOCVD in-house, we might need to raise some more capital."
