Thermal Conductivity Characterization and Modeling of P-Type Metal/Semiconductor Nanocomposites

Semiconductor alloys with epitaxially embedded nanoparticles have been shown to be very promising materials for thermoelectric energy conversion applications. In this work, we report on thermal conductivity characterization of two classes of p-type nanoparticle-in-alloy composite materials: compensated InGaAs semiconductor matrix with randomly distributed ErAs nanoparticles, and GaSb and its alloys with embedded ErSb nanoparticles. The three omega method is used to measure thermal conductivity of all materials. It is shown that thermal conductivity of compensated p-type ErAs:InGaAs is comparable to the n-type ErAs:InGaAs and it reduces with the increase in the erbium concentration. ErSb:GaSb nanocomposites are intrinsically p-type and show a thermal conductivity substantially lower than the pure GaSb compound. By comparing nanostructured samples from alloyed (InGaSb) and unalloyed (GaSb) matrix materials, we show that alloying is complimentary to the role of the nanostructure in reducing thermal conductivity. We also discuss Boltzmann transport modeling that indicates an optimum nanocrystal size, and the prospects for further reductions in the lattice thermal conductivity.