Energy Relaxation and Cooling in Impure Bilayer Graphene at Low Temperatures

Abstract

Understanding the physical mechanism of heat dissipation is a matter of increasing concern from the perspective of waste heat management in nanostructure‐based devices. The impurity‐driven electron–phonon scattering is a significant channel for energy relaxation in graphene and its bilayer. The recently developed Keldysh formalism for single‐layer graphene (SLG) is extended to investigate the transport phenomena due to phonon interaction via the deformation potential in disordered bilayer graphene (BLG) at low temperatures within the impure limit, . It is observed that in the BLG system also, the temperature dependence of the relaxation rate and the cooling power are affected by the occurrence of disorder and screening, with the temperature exponent of pure BLG modified to in impure BLG. A comparison with the temperature and mean free path exponents of SLG reveals that the exponents in BLG turn out to be the same, but they both differ from the conventional 2DEG. However, the magnitude of the scattering rate and cooling power is more pronounced in BLG in a low‐temperature regime. As the magnitude of the relaxation rate and the cooling rate varies with impurity, the impurity‐assisted electron–phonon scattering has rich implications on hot carrier transport in BLG devices.