Design and fabrication of a thermoelectric nanowire characterization platform and nanowire assembly by utilizing dielectrophoresis

We demonstrate the fabrication of a novel micromachined Thermoelectric Nanowire Characterization Platform (TNCP) which will be utilized to characterize the thermoelectric properties of a single thermoelectric Bi2Te3 nanowire. The TNCP is composed of two adjacent, symmetric and suspended Si cantilevers with a length of 1000 μm, a width of 100 μm and a thickness of 10 μm. Microheaters, temperature sensors and electrodes are fabricated on both cantilevers. Furthermore, a V-groove is integrated on the tip of each cantilever, in order to accommodate one single nanowire inside. The integration of the single nanowire onto the TNCP is conducted by means of dielectrophoresis (DEP) in combination with a controlled deposition and evaporation of a water droplet where the nanowires are dispersed. In addition to the DEP application, surface modifications are applied to form hydrophilic and hydrophobic surfaces on different parts of the cantilevers, to improve the water droplet deposition. In the end, one single nanowire is successfully integrated in the V-grooves bridging the cantilevers and ready for the further thermoelectric properties measurements. Within a series of 200 experiments, approximately 10% of them are successfully observed with one nanowire situated in the V-grooves as desired. The optimal applied voltage and frequency parameters for the DEP deposition process are in the range from 5 V to 8 V, and from 150 kHz to 8 MHz respectively.