Tunable Thermal Conductivity of Silicene by Germanium Doping

Silicene possesses excellent electronic properties and low thermal conductivity and hence is a potential material for thermoelectric applications. The key to improve the thermoelectric efficiency of silicene relies on opening a bandgap to enhance the thermopower and suppressing the lattice thermal conductivity. Based on first-principle calculations, we propose germanium doping as an effective way to tailor the thermal conductivity of silicene. The electronic transport properties of silicene is not affected by Ge doping, while the room-temperature thermal conductivity is significantly reduced by 62 % for a doping concentration of 6 %. The depression of phonon transport is attributed to the low-frequency phonon softening and enhanced phonon scattering by Ge doping. Our theoretical results will be beneficial for experimental modulating the thermal and thermoelectric properties of silicene and many other two-dimensional materials.