Abstract
We report a comparative investigation of the magnetic response of long channel AlGaN/AlN/GaN heterostructures (Hall-field effect transistor devices) grown on three different semi-insulating templates on silicon and sapphire. From Hall effect measurements conducted up to 573 K (300 degrees C), we find that some of these specific devices can be used as magnetic sensors in a large temperature range (similar to 600 degrees C) with a magnetic sensitivity close to 60 V/A T and a small thermal drift. On the best sample, between liquid helium temperature and 300 degrees C, the average value of the thermal drift is only -7 ppm/degrees C. (C) 2008 American Institute of Physics.