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industry  wide bandgap technologies


Kyma’s major breakthrough in materials,growth tools and products


than 40 x 2-inch wafers in a single growth run. Both tools are highly automated, with cassettes and multi-wafer platters enabling up to 24 hours of growth on dozens of platters of wafers without operator intervention. Market response to these products is positive, and we are now evaluating the outsourcing of manufacturing, in order to support an anticipated hike in shipments of dozens of PVDNC growth systems during the next few years.


From materials to devices Last September, we passed another important milestone – the launch of our first device. It’s a photoconductive semiconductor switch (PCSS), and its most important attribute is that it is the highest power semiconductor switch of its size with a sub- nanosecond response time. When naming this switch, we intentionally went for a double entendre: ‘Kyma Optical’ and ‘Knock Out’. The latter is deserved, because we have knocked out some of our own electronics when scrutinizing it in our high- speed switch testing facility!


This happens because when high electrical power is switched at such speed, electromagnetic radiation is generated with frequencies above 1 GHz. We are still learning about the details of the waveform but expect that a broadband pulse is generated with frequencies as high as 10 GHz or higher. Such an electromagnetic pulse can induce currents in nearby electronics. If the induced currents are high enough, the equipment can fail irreversibly. At lower currents or durations, the equipment may just need a reboot, which we have done many times.


Our motivation for developing the KO-Switch can be traced back as far as 2006, when we read a paper written by scientists at Lawrence Livermore National Laboratory: Wide bandgap extrinsic photoconductive switches. In this, they compared the performance of a PCSS made from GaN with one built from SiC. The impression we had after reading the paper was that GaN can be superior to SiC in this arena, because it enables the fabrication of devices that respond more quickly and have a lower on-state resistance. We were very excited about the potential for GaN PCSS, and we explored many avenues that might allow us to


64 www.compoundsemiconductor.net March 2013


supply materials or devices into a larger programme. Unfortunately, our initial efforts bore no fruit, and at times we felt that SiC had won the day – at least, for a while. That’s not surprising, given that SiC wafers are larger, more plentiful and cheaper than our specially grown KO-GaN. Despite this setback, we persisted, and we were rewarded for our efforts. We won a couple of modest US DoD contracts to build our own PCSS devices with support from the Air Force Research Laboratory, and these switches have produced very promising results. It took us very little time to beat the values for standoff voltage, on- resistance, and switching current reported by LNLL, and now, even though this work is still in its infancy, we can switch over 10 kV and 10 kA in less than 1 ns with very low on-resistance. The testing of our switch has involved a high performance YAG laser equipped with an optical parametric oscillator and frequency doublers. This allows us to probe our device with a broad range of excitation wavelengths


and pulse energies. We find that this switch has a very broad spectral response, which bodes extremely well for ultimate implementation using commercial, off-the-shelf fibre lasers and diode lasers.


Applications for our switch include electric circuit fault protection, low jitter pulsed power, and support of several applications in the commercial, defence, and homeland security sectors. Our first KO-switches were built as part of a government-sponsored R&D programme, and we are still delivering devices under DoD support. Several devices have been sold this year, and we are now in discussions with several key corporate and government players. They are all interested in exploring this technology for US defence and homeland security applications.


What’s next?


One of the biggest benefits of diversification, whether it is achieved organically or by acquisition, is that it leads to an expansion of our core competencies. In turn, this inevitably leads to new product opportunities, which sometimes draw on a portfolio of in-house expertise. In our case, this has happened with the KO-Switch. We are committed to growing the business associated with our existing products, while continually seeking out new commercial opportunities.


This year our goals are: To increase our PVD AlN template manufacturing capacity; get our equipment products into the market; and surpass certain performance milestones with our KO-Switch, which would make a compelling case for its insertion into several demanding applications. On top of this, we are aggressively pursuing the development of several new products in partnership with Duke University and others. Watch out for exciting new product announcements during the remainder of this year.


 We thank the Air Force Research Laboratory for supporting our construction of a high speed switch testing facility.


© 2013 Angel Business Communications. Permission required.


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