A Highly Linear Temperature Sensor Using GaN-on-SiC Heterojunction Diode for High Power Applications

Silicon carbide (SiC) power devices have been commercialized up to 1.7 kV with operating temperatures up to 573 K. The temperature limitations of SiC devices are generally derived from limitations in packaging and a lack of information on safe operating temperature regimes. Therefore, it is highly desirable to develop reliable temperature sensing techniques that can better take advantage of the SiC devices in high power applications. In this letter, ten gallium nitride (GaN)-on-SiC heterojunction diodes, aiming at high-power and high-temperature sensing applications, were fabricated using concentric ring geometry. These sensors can be monolithically integrated into GaN-on-SiC RF/Microwave power devices with fast-switching frequency and high-power density. The temperature dependent characteristics of the forward voltage drop at fixed current (
$V_{D}-{T}$
) of these heterojunction devices and their sensitivities (mV/K) are comprehensively characterized in a temperature range from 300 to 650 K. These devices exhibit a high degree of linearity in their
$V_{D}-{T}$
characteristics, which indicates the potential to be used as temperature sensors up to 650 K.