Single-Material Graphene Thermocouples.

On-chip temperature sensing on a micro- to nanometer scale is becoming more desirable as the complexity of nanodevices and size requirements increase and with it the challenges in thermal probing and management. This highlights the need for scalable and reliable temperature sensors which have the potential to be incorporated into current and future device structures. Here, we show that U-shaped graphene stripes consisting of one wide and one narrow leg form a single material thermocouple that can function as a self-powering temperature sensor. We find that the graphene thermocouples increase in sensitivity with a decrease in leg width, due to a change in the Seebeck coefficient, which is in agreement with our previous findings and report a maximum sensitivity of $\Delta S \approx$ 39 $\mathrm{\mu}$V/K.