SCALE UP OF Si/Si0.8Ge0.2 AND B4C/B9C SUPERLATTICES FOR HARVESTING OF WASTE HEAT IN DIESEL ENGINES
Thermoelectric devices show significant promise for harvesting and recovery of waste heat from diesel engines, exhaust systems and industrial heat sources. While these devices convert a heat flow directly into electrical energy, cooling can be accomplished by the same device with application of a direct current (Peltier effect). Conversion efficiencies of bulk thermoelectric systems, however, are still too low for economical power conversion in diesel powered vehicles and heavy vehicles. Thermoelectric superlattice devices have demonstrated the potential for increased efficiencies and utilization of waste heat. Although reported efficiencies are well above 15%, fabrication costs are still too high for use in diesel engine systems. To realize this efficiency goal of {approx} 20% and power generation in the kWMW range, large quantities of superlattice materials are required. Additionally, if the figure of merit (ZT) of these superlattices can be increased to > 2, even less superlattice material will be required to generate electric power from heat in diesel engines. We report on development of and recent progress in scale up of Si/Si0.8Ge0.2 and B4C/B9C superlattices for thermoelectric applications, and particularly for fabrication of large quantities of these materials. We have scaled up the magnetron sputtering process to produce large quantities of Si/Si0.8Ge0.2 and B4 C/B9C superlattices with high ZT at low cost. Quantum well films with up to 1000 layers were deposited onto substrate areas as large as 0.5 m2 by magnetron sputtering. Initial studies showed that the power factor of these SL's was high enough to produce a ZT significantly greater than 1. Both p- and n-type superlattices were fabricated to form a complete thermoelectric power generating device. ZT measurements will be reported, and based on measured power factor of these materials, should be significantly greater than 1. These results are encouraging for the use of quantum well materials in thermoelectric power generation.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EE) (US)
- OSTI ID:
- 828949
- Report Number(s):
- CONF-200308-107; TRN: US200428%%919
- Resource Relation:
- Conference: 9th Diesel Engine Emissions Reduction (DEER) Workshop 2003, Newport, RI (US), 08/24/2003--08/28/2003; Other Information: PBD: 24 Aug 2003
- Country of Publication:
- United States
- Language:
- English
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