Experimental Thermopower of Quantum Wires
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Experimental Thermopower of Quantum Wires M. V. Vedernikov, O. N. Uryupin, B. M. Goltsman, Yu. V. Ivanov, and Yu. A. Kumzerov A.F.Ioffe Physical-Technical Institute, 194021, St.Petersburg, Russia ABSTRACT Experimental investigation of thermoelectric properties of nanowires with diameter of about 5 nm was carried out. Chrysotile asbestos (a natural mineral) was used for a sample preparation. Its nano-sized channels were filled under pressure by melted InSb or Te. The measurements showed that temperature dependences of electrical resistance and thermopower of produced quantum wires differ considerably from corresponding dependences of bulk materials. It is possible to conclude that the results obtained are better described by Lattinger liquid model than by usual Fermi gas one. INTRODUCTION Hicks and Dresselhaus were the first who attracted attention to special thermoelectric properties of low-dimensional semiconductor superlattices in their theoretical searches [1,2]. They showed that transport properties of quantum well and quantum wire superlattices change with decreasing of well thickness or wire diameter in such a way when thermoelectric figure of merit Z increases progressively. This increase begins below 10 nm size and can be very significant: the most important dimensionless parameter ZT can achieve a value 10. A usage of so effective materials would give dramatically great possibilities in thermoelectric energy conversion. This is why the idea initiated a lot of investigations both theoretical and experimental. More detailed theoretical investigation was necessary, however, because Hicks and Dresselhaus have used the simplest model that considered a change of electronic spectrum of low-dimensional objects only (due to a space quantization) but neglected other phenomena. The most important is to take into consideration an influence of electron confinement on electron mobility that was believed constant by Hicks and Dresselhaus. A series of the later works showed that Hicks-Dresselhaus effect is balanced by other effects and some significant increase of the power factor should be not observed (see for example Ref. [3]). However the nature of transport properties of low-dimensional structures differs from 3D state and needs further investigation. In order to advance in solution of the problem, note that physics of one-dimensional structures has the long history. We shall not try to review here all aspects of the problem but remind only that Fermi gas (Fermi liquid) model is inapplicable to one-dimensional systems: electron-electron interaction must be taken into consideration. A model of quantum liquid describing electronic properties of one-dimensional conductor was advanced by Luttinger in 1963 (“Luttinger liquid”). The modern version of the theory one can find in Ref. [4]. A substance, whose electronic system follows to Luttinger liquid theory, has to have rather specific electronic properties. Particularly transport properties were investigated theoretically by Kane and Fisher: electrical conductance in 1992
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