Window of Opportunity Crystal Clear for Blue Lasers

Channel surfers beware! Your video viewing partner may soon be able to place a disc into the home entertainment center and not click another button for the rest of the afternoon. This is all thanks in part to Cermet, Inc. (Atlanta, GA), which has developed a low-cost alternative to vapor growth for making zinc oxide crystals--a finding that may soon land Cermet on the supply chain for blue lasers. Blue lasers, with their shorter wavelength, are expected to allow digital video disc (DVD) systems to store over 2.5-times more information (about six hours of video and sound) than those using red lasers; however, these systems will not be available on a widespread basis until they are economically feasible.

Cermet plans to supply zinc-oxide substrates to blue laser manufacturers as an alternative to sapphire substrates currently available. While the zinc-oxide substrates themselves will be priced competitively with sapphire, they will actually result in big cost savings to blue laser producers because they eliminate the need for additional processing. Gallium nitride (GaN) is the material of choice for blue lasers. Sapphire substrates have a lattice mismatch with the GaN layers of about 16 percent, which forces technicians to grow extra layers of GaN--at a cost ranging from $700 to 1,000 per layer--on the substrate. Zinc-oxide substrates, on the other hand, only have a 2-percent lattice mismatch with GaN so they do not require the extra layers.

The basis for Cermet's innovation is a pressurized melting process, which uses a high-pressure chamber at more than 100 atmospheres, induction heating, and proprietary materials for its crucible. Much of its work was funded through a Phase II BMDO STTR contract in conjunction with Georgia Tech Research Institute and through a Phase I BMDO SBIR contract to develop better materials for high-power electronics, such as wide-bandgap semiconductors, used in ballistic missile defense. In addition to zinc-oxide, Cermet is also crystallizing aluminum nitride and GaN with this process. Cermet has since patented the process and related equipment and is providing substrate samples for blue lasers to a major electronics corporation for testing. Centimeter-sized substrates will be available in the next few months for blue laser applications.