Effect of built-in-polarization field on intrinsic and extrinsic thermal conductivity of InN

Abstract

The effect of built-in-polarization field on intrinsic and extrinsic lattice thermal conductivity of InN has been investigated theoretically. The built-in-polarization field modifies elastic constant, phonon velocity and Debye temperature of InN. Using these modified parameters, the relaxation time of phonons in various scattering processes at room temperature has been computed as a function of phonon frequency for with and without built-in-polarization field. The result shows that built-in-polarization field enhances the relaxation time of phonons. This implies longer mean free path of phonons. The Callaway model of phonon thermal conductivity has been used to estimate the effect of built-in-polarization field on intrinsic and extrinsic thermal conductivity of InN. The theoretical analysis shows that up to a certain temperature, the polarization field acts as negative effect and reduces the intrinsic and extrinsic thermal conductivity. However, after this temperature, both thermal conductivity are significantly contributed by polarization field. This gives the idea of temperature dependence of polarization effect, which signifies pyro-electric character of InN. The intrinsic thermal conductivity of InN at room temperature including built-in-polarization field is found to be enhanced by 28 %. However, at room temperature, the extrinsic thermal conductivity with built-in-polarization mechanism is found to be enhanced by 15 %. The method, we have developed may be taken in the simulation of heat transport in optoelectronic nitride devices to minimize the self-heating processes and in polarization engineering strategies to optimize the thermoelectric performance of InN alloys.