Significant decrease of the lattice thermal conductivity due to phonon confinement in a free-standing semiconductor quantum well

Lattice thermal conductivity of a quantum well limited by umklapp, impurity, and boundary scattering was investigated theoretically by taking into account dispersion of confined acoustic-phonon modes. We show that strong modification of phonon group velocities due to spatial confinement leads to a significant increase in the phonon relaxation rates. From the numerical calculations, we predict a decrease by an order of magnitude of the lattice thermal conductivity in a 100-A-wide free-standing quantum well. Our theoretical results are consistent with recent experimental investigations of the lateral thermal conductivity of nitride/silicon/oxide membranes conducted in our group. S0163-18299800928-X Thermal properties of semiconductor nanostructures and superlattices have recently attracted a lot of attention. This is primarily due to two major factors. The first one is a continuous scaling down of the feature sizes in microelectronic devices and circuits, which leads to an increase in power dissipation per unit area of the semiconductor chip. Under such conditions, the influence of size effects on thermal conductivity becomes extremely important for device design and reliability. 1 The problem of thermal management is even more severe for photonic devices such as vertical cavity surface emitting lasers, in which the heat generation density