Transient effects of temperature disturbance on phonon characteristics in thin diamond film

Energy transport, in general, is governed by scattered and ballistic phonons in thin dielectric films. Ballistic phonon contributions become important when the film thicknessis reduced. In the present study the influence of temperature disturbance on phonon transport characteristics in thin diamond films are examined. The time-dependent Boltzmann equation is incorporated for phonon transport in a two-dimensional diamond film. In order to assess ballistic phonon contribution to transport characteristics, a frequency-dependent solution is adopted in the analysis. Temperature pulsation at one edge of the film is considered to examine the film response to the temperature disturbance for various film thicknesses. It is found that ripples are formed on the equivalent equilibrium temperature curve, which is more pronounced in the near region of the high temperature edge. Ballistic phonons contribute significantly to the temperature rippling, and the phase shift is observed between the temperature ripples and the pulsation frequency of temperature at the film edge.