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Kyma markets photoconductive switch family

The firm is marketing its gallium nitride switches which respond to all wavelengths in the visible region of the electromagnetic spectrum
Kyma Technologies, supplier of crystalline AlN and GaN materials and related products and services, has launched its first device product, the KO-Switch.

Kyma KO-Switch

This high speed, high power, bulk GaN based photoconductive semiconductor switch (PCSS) combines high breakdown voltage, low on-resistance with fast switching speed.

The KO-Switch uses a specially tailored form of Kyma’s crystalline semi-insulating bulk GaN, and is designed to block up to 2,000V and to drive 40A into a 50 Ω load at 80,000W in power when turned on with an appropriate optical beam.

Kyma’s KO-Switch development team is led by Chief Engineer Bob Metzger with close support from Chief Scientist Jacob Leach. Recently, Processing Technician Devin De Keczer joined the team to assist the commercialisation efforts.

The KO-Switch is claimed to respond to all wavelengths in the visible region of the electromagnetic spectrum.

Since the bandgap of KO-GaN lies in the ultraviolet, excitation of the KO-Switch by visible light is called extrinsic excitation. Blue and green light works especially well which makes commercial off the shelf blue and green lasers good excitation source candidates.

Kyma recently established PCSS device testing facility near its corporate headquarters is equipped with a 5 nanosecond (ns) pulsed Nd:YAG solid state laser with an optical parametric oscillator. It enables continuous wavelength tuning from the near infrared all the way into the near ultraviolet.

Kyma’s tests show rapid response of the KO-Switch to their laser, providing an upper limit of ~1 ns response time. Indeed, the switch may be significantly faster. To further investigate response time, Kyma provided several KO-GaN samples to three independent optical physics experts in the government, academic, and private sectors.

The results of their independent investigations were in close agreement and showed an average photoexcited carrier lifetime of 90 picoseconds, with the fastest and longest measured values being 18 and 200 picoseconds, respectively.

“The KO-Switch could be a game changer for a number of applications in the medical, homeland security, and defence sectors,” states Metzger. “We are currently working with several partners to identify the most promising early adopter applications.”

Kyma President and CEO Keith Evans adds, “Bob and Jacob have advanced this exciting new technology at an incredible pace. And none of it would be possible without the vision and support of John Blevins and his colleagues in the Aerospace Components & Subsystems Technology Division of the Sensors Directorate of US Air Force Research Laboratory.”

Kyma is also investigating use of multiple devices in parallel and series and also believes that a 100kV KO-Switch device is possible in the near future. The company’s technical staff is investigating a number of different PCSS topologies, some of which could be integrated into ultra-high performance GaN based opto-electronic integrated circuits (OEICs).

A large design space exists when one considers that sub-bandgap light could be brought into the desired excitation volume in any number of ways, including using waveguides and fibre optics.

Research into extrinsic photoconductive semiconductor switches has been especially active at Lawrence Livermore National Laboratory, Texas Tech University, and University of Missouri-Columbia.

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