EFFECT OF HYDROGEN PASSIVATION ON THE THERMAL CONDUCTIVITY OF NANOPOROUS CRYSTALLINE SILICON: A MOLECULAR DYNAMICS STUDY

摘要

Effect of hydrogen passivation on thermal conductivity of nanoporous crystalline silicon was investigated using equilibrium molecular dynamics (MD) simulations from 500 to 1000 K. The porosity varied from 8% to 38% while the pore diameter ranged from 1.74 to 2.93 nm. Hydrogen passivation of the pore surface was found to reduce thermal conductivity by about 20% at 500 K due to enhanced phonon scattering by the passivated atoms at the nanopore surface. The effect of passivation diminished with increasing temperature. In fact, the phonon density of states at high temperatures was similar for both passivated and unpassivated silicon atoms. Finally, the thermal conductivity k was found to be linearly proportional to (1 - 1.5fv)/(Ai/4) where f_v is the porosity and A_i is the pore interfacial area concentration. This scaling law was previously established for unpassivated silicon using non-equilibrium MD simulations.