Kyma Technologies Inc of Raleigh, NC, USA, which provides crystalline gallium nitride (GaN), aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) materials and related products and services, has completed its initial investigation into the device reliability of its KO-Switch (its first device product), which was launched last September.
A next step in studying the characteristics of the KO-Switch is to measure how stable its performance is under various device operating scenarios, says the firm. Since many of the applications that the KO-Switch are being considered for require impedance matching at the 50Ω resistance level, it is interesting to operate the KO-Switch under conditions that target an on-resistance (Ron) near 50Ω and to see if Ron drifts over time or as a function of another variable such as operating temperature. Additionally, the fast switching speed of the KO-Switch becomes a real benefit for many applications if the device can be switched on and off thousands or even millions of times without significant degradation, adds the firm.
Kyma's Bob Metzger, chief technology officer, and Jacob Leach, chief science officer, 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 1000V (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 = 20Ω. Instantaneous current passing through the 2mm diameter device was 50A while the switch was closed. After subjecting the switch to >1,000,000 close/open cycles, the change in Ron was less than 1%, which is within the error of the measurement system. The conclusion is that there is no noticeable degradation in Ron after 1,000,000 device operations.
"We are very encouraged at the excellent reliability we find under these operating conditions, which are relevant for several different customer applications," said Leach. "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 behavior which will inform our future device improvement plans."
"We believe these are the first publically disclosed device reliability results obtained on a wide bandgap photoconductive switch," says Metzger. "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."
Kyma has sold several units of the KO-Switch already in 2013 and is working with a number of large companies to understand its potential to support several high performance high power switching applications.
