GaN‐based Schottky diodes for hydrogen sensing in transformer oil

We report the demonstration of robust, GaN‐based hydrogen sensors for use directly in transformer oil. These 1 mm2 Schottky diodes were immersed in a closed loop with Voltesso insulating oil for 21 months of continuous testing. They showed good reproducibility in response to hydrogen gases, while exposed to varying temperatures. We will briefly discuss the transformer monitoring application, the device design and fabrication process, and the sensor performance from 21‐months of testing. Transfer functions from oil temperature and dissolved gas concentration have been quantified, and those will be briefly discussed. These new sensors offer a novel alternative to electrochemical cell‐based sensors for various applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)