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INDUSTRY GaN DEVICES Detecting levels of NO2 is very important, because


monitoring devices. Sensors on the market today do not satisfy all these requirements. They are either too costly, too bulky, or fail to provide the NO2


emissions of this gas can jeopardize human health and cause ecosystem damage. Consequently, there is a great demand for ultra-compact, portable and even wearable low-cost continuous NO2


sensitivity or reversibility required for continuous air quality monitoring, where detection at concentrations of less than 50 parts-per-billion is needed.


Figure 5. The low turn on voltage (a) and low leakage current of imec’s novel, proprietary gate-edge terminated diodes make them ideal for use in electrical systems delivering highly efficient switching.


results from them being majority-carrier Schottky diodes. Short recovery times slash switching losses, enabling these devices to increase the efficiency in electrical systems, such as solar inverters. We expect that once these devices appear on the market, they will replace silicon and SiC diodes, because they offer a better performance than the former, and are inherently cheaper than the latter.


Detecting gases


Our 200 mm GaN-on-silicon platform is not restricted to the production of power devices: it is also capable of producing NOx


sensors and LEDs,


while RF devices offer an opportunity for future collaboration. It is astonishing how the same GaN material and platform can be used for so many different applications!


It is possible to meet all these requirements with our GaN-based technology that can yield devices with a reaction time below 2 seconds and a detection limit below 1 ppb for NO2 With these devices, the level of NO2


is revealed by variations in the resistance of the two-dimensional electron gas in the channel. These devices are showing much promise, having already been used to monitor NO2


(see Figure 6). concentration


inside


underground parking garages, where they have produced very good results.


It is clear that GaN devices are accounting for an ever-larger proportion of the semiconductor market. The 200 mm GaN-on-silicon platform that we have developed with our partners will help to accelerate the increasing deployment of this wide bandgap semiconductor, which can be used to make many different devices. Some companies might find it a formidable challenge to make the transition to manufacturing GaN devices, but this should not be too daunting, as we can help them to gain easy access to this technology, accelerate their internal GaN development and provide them with access to next-generation GaN-based epitaxy and device technologies currently under development.


Figure 6. imec’s GaN- on-silicon platform can


be used to make NO2 sensors (a). Detection of this pollutant oxide is possible downto levels of 10 parts per billion (ppb) and below, with the sensor delivering a quick response to changes in concentration that lead to changes in the resistance of a two-dimensional electron gas.


52 www.compoundsemiconductor.net October 2014 Copyright Compound Semiconductor


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