2D Materials for Universal Thermal Imaging of Micro- and Nanodevices: An Application to Gallium Oxide Electronics

We highlight the flexibility of two-dimensional (2D) materials for advancing current technologies through the introduction of 2D Raman thermography (2DRT). 2DRT combines monolayer materials and Raman spectroscopy to perform thermal imaging of micro- and nanodevices. In contrast to peak shift and line width based methods for Raman thermal analysis, 2DRT uses the anti-Stokes/Stokes intensity ratio which is only sensitive to temperature. To demonstrate the technique, monolayer molybdenum disulfide (MoS 2 ) was transferred to the surface of devices based on β-gallium oxide (Ga 2 O 3 ), an emerging ultrawide-bandgap semiconductor for high-frequency and high-power applications. The validation of the technique was performed on an (AlGa) 2 O 3 /Ga 2 O 3 modulation-doped field effect transistor by using nanoparticle-assisted Raman thermometry. The peak operating temperature, a critical device performance metric, is underestimated by ∼30% by using standard Raman thermometry when compared to 2DRT. Finally, the 2D thermal imaging capabilities of 2DRT were demonstrated on an (AlGa) 2 O 3 /Ga 2 O 3 transmission line measurement structure.