Control of Heat and Charge Transport in Nanostructured Hybrid Materials
Abstract
The proposed research efforts focused on the wafer-scale manufacture of silicon based thermoelectric modules with ZT > 2. Recent measurements in our groups have yielded device ZT values of 0.4 on thermoelectric modules consisting of vertically oriented silicon nanowires. This is the highest reported ZT for a silicon based thermoelectric module. Based on this work, here, we aimed to develop nanostructured thermoelectric modules utilizing two different silicon morphologies: 1. Deep nanoholes in bulk silicon with aspect ratios exceeding 10,000 and 2. Extremely long silicon nanowires with aspect ratios exceeding 10,000. Temperature differences as high as 800 ??C are achievable for both types. The bulk nanostructured silicon modules were produced using block copolymer nanolithography, which is a polymer-based nanotemplating technique. This technique is amenable to roll-to-roll processing making wafer-scale manufacturing of bulk nanostructured silicon thermoelectrics practical. In fact, the cost of block copolymer is comparable to the cost of standard photoresists. Our current ability to reach ZT values ~ 0.4 is a direct consequence of the dramatically low thermal conductivity of the silicon nanostructures. Specifically, experiments on an array of 20 nm diameter vertically oriented silicon nanowires have demonstrated thermal conductivities k ~ 0.4 W/m-K, which is below the amorphous limit.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 21, 2015
- Accession Number
- ADA623617
Entities
People
- Akram Boukai
Organizations
- University of Michigan