Low-Frequency Acoustic Phonon Temperature Distribution in Electrically Biased Graphene

On the basis of scanning thermal microscopy (SThM) measurements in contact and lift modes, the low-frequency acoustic phonon temperature in electrically biased, 6.7-9.7 mu m long graphene channels is found to be in equilibrium with the anharmonic scattering temperature determined from the Raman 2D peak position. With similar to 100 nm scale spatial resolution, the SThM reveals the shifting of local hot spots corresponding to low-carrier concentration regions with the bias and gate voltages in these much shorter samples than those exhibiting similar behaviors in the infrared emission maps.