Optimal thickness of silicon membranes to achieve maximum
thermoelectric efficiency: a first principles study
Claudia Mangold, Sanghamitra Neogi and Davide Donadio, Appl. Phys. Lett., 109(5), 053902 (2016)
First principles study of the electronic properties of ultra-thin crystalline silicon membranes with thickness upto 12 nm with native oxide surface layers

Silicon nanostructures with reduced dimensionality, such as nanowires, membranes, and thin films, are promising thermoelectric materials, as they exhibit considerably reduced thermal conductivity. Here, we utilize density functional theory and Boltzmann transport equation to compute the electronic properties of ultra-thin crystalline silicon membranes with thickness between 1 and 12 nm. We predict that an optimal thickness of ~7 nm maximizes the thermoelectric figure of merit of membranes with native oxide surface layers. Further thinning of the membranes, although attainable in experiments, reduces the electrical conductivity and worsens the thermoelectric efficiency.