Air‐Sensitive HfSe₂‐Based Temperature Indicator for 2D Electronic Devices

Joule heating‐induced temperature distribution is a critical thermal issue in 2D electronics, with implications for their performance optimization and potential device failure. Herein, the feasibility of using van der Waals integrated HfSe2 to indicate surface temperature distribution in 2D electronics is demonstrated. The air oxidation of HfSe₂is found to be sensitive to its thickness and ambient temperatures, with the resulting oxidation products varying accordingly. Joule heating from the operation of 2D devices rises the local temperature, which accelerates the air oxidation of HfSe₂and changes the composition of the oxidized HfSe₂accordingly. By observing the surface conditions of HfSe₂with a Raman spectroscope or an optical microscope, the temperature distribution is semiquantitatively revealed for a graphene ribbon device, the accuracy of which is verified by the finite element simulations. Using the HfSe₂, temperature indicator provides a simple and rapid method for investigating thermal issues and related device failure mechanisms in 2D electronics.