High thermoelectric figure of merit of quantum dot array quantum wires.

How to design silicon-based quantum wires with figure of merit ($ZT$) larger than three is under hot pursuit due to the advantage of low cost and the availability of matured fabrication technique. Quantum wires consisting of finite three dimensional quantum dot (QD) arrays coupled to electrodes are proposed to realize high efficient thermoelectric devices with optimized power factors. The transmission coefficient of 3D QD arrays can exhibit 3D, 2D, 1D and 0D topological distribution functions by tailoring the interdot coupling strengths. Such topological effects on the thermoelectric properties are revealed. The 1D topological distribution function shows the maximum power factor and the best $ZT$ value. We have demonstrated that 3D silicon QD array nanowires with diameters below $20~nm$ and length $250~nm$ show high potential to achieve $ZT\ge 3$ near room temperature.