Size effect on the phonon heat conduction in semiconductor nanostructures

Abstract

Abstract Lattice thermal conductivity for silicon nanowires and quantum well are theoretically investigated in the temperature range from 2K to 300K. The modified Gallaway method for bulk crystal is used for calculating lattice thermal conductivity. All important phonon relaxation mechanism such as Umklapp scattering, Mass-difference scattering and boundary scattering are calculated at 300K. The result show that the modification of the acoustic phonon modes and phonon group velocities due to spatial confinement of phonons lead to significant increase in the all phonon relaxation rate. From our numerical results, we predicate a significant decrease of the lattice thermal conductivity in cylindrical nanowires with diameter (D=10-nm), and quantum well with thickness of the same size, results compared to that of the reported experimental as well as theoretical values.

Keywords

• phonon heat
• semiconductor nanostructures
• umklapp scattering
• mass-difference scattering