Above 500 °C operation of InAlN/GaN HEMTs

Due to their ceramic-like thermal/chemical stability GaN-based HEMTs are expected to be of high robustness and may also be a prime candidate for reliable high temperature operation. In gas sensing AlGaN/GaN heterostructures have been investigated up to 800¿¿C. In a simple proof-of-concept experiment InAlN/GaN HEMTs have been operated at 1000¿¿C for a short period of time in vacuum. However in respect to continuous operation most tests have been limited to a temperature range below 500¿¿C. Here a continuous test is described operating devices under 1 MHz large signal conditions for 250 hrs at a given temperature increased in steps of 100¿¿C (in vacuum), concentrating on the temperature range above 500¿¿C, until failure.