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You can rely on Kyma's first III-nitride power device

The supplier of crystalline aluminium and gallium nitride materials found that there is no noticeable degradation in the on resistance of its KO-Switch after 1 million device operations
Kyma Technologies has completed its initial investigation of the device reliability of its recently launched KO-Switch.

The company first announced the launch of the KO-Switch as its first device product in September last year.


The module was realised from an Air Force Research Laboratory (AFRL) R&D investment managed by John Blevins of AFRL and led by Bob Metzger, Kyma’s Chief Technology Officer. 

Characteristics of the device operation were presented last month at Photonics West 2013 by Jacob Leach, Kyma’s Chief Science Officer.

Kyma also conducted tests to see how stable the KO-Switch was by measuring its performance under various device operating conditions.

Many of the applications that the KO-Switch is being considered for require impedance matching at the 50Ω resistance level. Hence Kyma operated the KO-Switch under conditions that target an on-resistance (RON) of 50Ω and see if the RON drifted over time or as a function of another variable such as operating temperature.

The fast switching speed of the KO-Switch will really benefit many applications if the device can be switched on and off thousands or even millions of times without significant degradation.

Taking that in mind, Leach and Metzger designed a test to repeatedly turn the KO-Switch on and off over 1,000,000 times while monitoring RON and measuring the current through the device, which was biased at 1,000 volts (in the off condition).

The 532nm excitation laser was adjusted to excite the device with 5ns wide pulses in a 10Hz pulse train and was coupled to the device to set the initial RON to 50 Ω. Instantaneous current passing through the 2mm diameter device was 50A while the switch was closed.

After subjecting the switch to over 1,000,000 close/open cycles, the change in RON was less than 1 percent, which is within the error of the measurement system. So, Kyma asserts there was no noticeable degradation in RON after 1,000,000 device operations.

Leach comments, “We are very encouraged at the excellent reliability we find under these operating conditions, which are relevant for several different customer applications. Next we want to begin pushing the device harder, at higher currents and laser pulse energies, for example, and under higher bias voltage. I am confident we will find the edges of its reliability behaviour which will inform our future device improvement plans.”

Metzger adds, “We believe these are the first publically disclosed device reliability results obtained on a wide bandgap photoconductive switch. This is an exciting new product space for us to get involved in and we look forward to seeing how far we can take the switch in terms of high performance applications.”

Leach and Metzger are in the process of preparing a scientific publication that will describe the details of the device reliability study.

Kyma has already sold several units of the KO-Switch this year and is working with a number of large companies to understand its potential to support several high performance high power switching applications.

According to Kyma, the market for nitride semiconductor devices was roughly $10 billion in 2012 and is expected to surpass $60 billion over the long term, including $30 billion in visible lighting applications and $30 billion in power electronics applications.

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