Seebeck Coefficient of Nanowires Interconnected into Large Area Networks

Abstract

We measured the macroscopic Seebeck coefficient of silicon nanowires (SiNWs), organized in a highly interconnected networks on large areas (order of mm(2)). The fabricated networks are very reliable with respect to random nanowire failure and are electrically and thermally equivalent to many SiNWs placed in parallel between the electrical contacts. The equivalent SiNWs have a macroscopic length of the order of millimeters and are very narrow (width smaller than 100 nm) so that they can be used to exploit thermoelectric properties at nanoscale for macroscopic electrical power generation and/or cooling. The measurement of the Seebeck coefficient S, facilitated by the macroscopic dimensions of the network, gives an insight into two questions, nanowire effective doping and carrier mobility, which are widely discussed in the literature. We found that the measured value of S is compatible with an effective doping that is higher than that of the original wafer. This higher doping is consistent with the value estimated from the measured electrical conductivity of the SiNWs with the assumption that the electron mobility inside the nanowire is equal to that of bulk silicon.

Effects of Size Reduction on the Electrical Transport Properties of 3D Bi Nanowire Networks

“…Due to the experimental difficulty to fabricate NWNWs with controlled hierarchical assembly and geometry, experimental data on the influence of wire interconnects on the transport properties are still scarce. [ 4,8,33,34 ]…”

Review of nanostructured devices for thermoelectric applications

“…The resistance of the net shows also a low sensitivity with respect to the non-uniformity (dispersion) of the nanowire width. The Seebeck coefficient of nanowire networks has been measured [101], and its value resulted in a good agreement with the doping, found by measuring the nanowire electrical conductivity. However, the measured doping concentration was slightly higher than the original doping concentration of the silicon top layer.…”

“…11. It is easy to demonstrate [100–101] that these very large area arrays of very narrow, micrometers long, silicon nanowires are equivalent to the parallel arrangement of very narrow SiNWs with a total length of several millimeters (see the top right sketch of Fig. 11).…”

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

“…A possible alternative approach is to define the nanostructures/nanowires by lithography and etching [ 64 , 65 ] (top down approach), using a suitable design to connect silicon platforms, which can be fabricated simultaneously with the nanostructures. The main advantage of this strategy is the high flexibility in the design of the device: nanostructures can be fabricated and positioned in precise positions and configurations.…”