Reducing thermal conductivity of crystalline solids at high temperature using embedded nanostructures

Thermal conductivity of a crystalline solid at high temperature is dominated by the Umklapp process because the number of high frequency phonons increases with temperature. It is challenging to reduce the thermal conductivity of crystalline solids at high temperature although it is widely known that, by increasing the atomic defect concentration, thermal conductivity of crystalline solids can be reduced at low temperature. By increasing the concentration of ErAs nanoparticles in ln _0.53Ga _0.47As up to 6 atom %, we demonstrate a thermal conductivity reduction by almost a factor of 3 below that of ln _0.53Ga _0.47As at high temperature. A theoretical model suggests that the mean free path of the low frequency phonons is suppressed by increasing the ErAs nanoparticle concentration.