Objective
Increased demand for solid state microcoolers and direct energy miniconverters has renewed the interest to the development of novel much more efficient thermoelectric materials. The search of such materials became an advanced problem of materials physics. The proposed approach to study and apply for this purpose the low dimensional structure systems corresponds to the latest and most advanced ideas in this field. Quantum confinement of carriers in low-dimensional structures, leading to an important increase of the subband density of states and hence, to an increase of the thermopower (Seebeck coefficient), as well as the increased phonon-boundary scattering, and modification of acoustic phonon spectra were responsible for experimentally observed enhancement of thermoelectric properties of these structures. However, mainly n-type structures were considered. In the frame of the INTAS project No 96-535, finished in March, 2000, n-type lead-salt quantum well (QW) structures were investigated and important results were obtained. Now it is of extreme importance to develop quickly p-type materials. This is absolutely necessary because for p-legs of thermoelements efficient p-type materials are needed too. The overall goal of the present joint research project is to develop a rigorous physical approach and advanced microelectronic technology for several specific p-type efficient thermoelectric QW structures.
The major objectives of the project are:
- to investigate theoretically thermoelectric opportunities of several concrete quasi-two-dimensional (Q2D) p-type lead telluride and germanium-silicon QW structures with expected high thermoelectric performance;
- to determine the optimal physical and geometrical parameters and to elaborate recommendations for the manufacture of structures with desirable thermoelectric properties;
- to develop the technologies for the fabrications of p-type QW structures with optimal parameters;
- to elaborate experimental methods for the characterization of obtained structures and to investigate their thermoelectric properties;
- to evaluate the potential of the utilization of these low-dimensional thermoelectrics in new thermoelectric devices;
- to enhance the efficient co-operation between the project teams in order to realize these researches and new more complicated ones for mutual benefit;
- to evaluate the economic aspects of obtained results.
The strategy for accomplishment of these objectives is to bring together and to combine already existing skills, facilities and experience of different research laboratories (including those accumulated during above-mentioned INTAS project). Two teams are from INTAS and three from NIS. The outline of this strategy is presented in the research program. The research programme is divided into a number of concrete tasks and subtasks whose realization is organized in cooperation with different partner teams. Task 1 is dedicated mainly to theoretical investigations. Task 2 is technological. The development of a suitable technology for the structures fabrication is of premier necessity. This is the most difficult part of the project, but it is feasible on the basis of our background. Task 3 is dedicated to the structure measurements. A true and close cooperation between project teams is foreseen.
The following results are expected to be the most important:
- development of rigorous physical models and theoretical formalisms for simulation of thermoelectric properties of several specific p-type QW structures;
- elaboration of computational methods and algorithms for modeling of the thermoelectric transport in systems of choice and determination of optimal structure parameters;
- development of a reliable technology for the fabrication of p-type PbTe and GeSi QW structures with optimal geometric and thermoelectric parameters;
- accurate measurement of structure parameters and their comparison with theoretically predicted ones;
- experimental identification of the transition from L-band to (-band carrier transport in p-type PbTe QW due to the confinement effect as a new opportunity to engineer more efficient thermoelectrics;
- evaluation of the maximal values of the thermoelectric power factor and figure of merit, estimation of the utilization potential of chosen structures for new thermoelectric devices;
- enhancement of an efficient cooperation between the teams involved in the project.
These results will provide new knowledge regarding thermoelectric phenomena in several MQW structures, which is very important for their more profound understanding. This will have a substantial impact on the investigation of new thermoelectric low-dimensional structures, so as it will permit more purposeful search of such materials. The results will be used in the manufacture of thermoelectric devices with higher figure of merit. They will also serve as a basis for development of new technologies for more efficient cooling systems fabrication.
Call for proposal
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84105 Beer-Sheva
Israel