In this section, the effects of confinement and orientation on the phonon transport
properties of ultra-thin silicon layers of various surface and transport orientations are investigated. Figure 4.7 shows the geometrical cross sections of the thin-layers considered. The layers have
,
,
, and
surface orientations. In all cases, we consider the
-axis to be parallel to the
orientation, and define the angle
of the transport direction counter-clockwise from the
-axis. Below, a complete analysis is presented by calculating the phononic properties and thermal conductance as a function of the angle
for the four surface orientations mentioned. The layer thickness
varies from
to
. The phononic dispersion, density of states, ballistic transmission, and effective group velocity of the different structures are calculated.
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