Thicknessdependences of the thermoelectric properties of Sn-doped single crystal Biwires

A.Nikolaeva^1,2, D. Gitsu¹, T. Huber³, L. Konopko¹

¹Institute of AppliedPhysics, Academy Sciences of Moldova, Academy str. 5, Chisinau, MD-2028, Moldova

²International Laboratory ofHigh Magnetic Fields and Low Temperatures, Wroclav, Poland

³ Department of Chemistry,Howard University, 525 College St. N.W. Washington, DC 20059

Thin Bi wires dopedwith Sn (0.02at%) are obtained in a glass cover with diameters (1*10²¸2*10³nm). Monocrystallinity,orientation and position of the Fermi level was controlled by Sh.d.H.oscillations. It was found thatthe Fermi level is in the band gap in L of the Brillouin zone, i.e.conductivity at low temperatures is determined by T-holes.

The electricalconductivity, magnetoresistance, Seebeck coefficient and power factor ofSn-doped Bi- wires at the temperature interval 4.2-300K were studied independence on diameter and elastic stretch.

At the elasticstretch of wires there occurs qualitative change of the FS topology –transition from one ellipsoidal FS to the two-ellipsoidal one, that was surelyregistered by the Sh.d.H. oscillations. In the process of this transition thepower factor and its dependence on temperature and magnetic field weremeasured.

It was found that theSeebeck coefficient in the rang 150-70K achieves the maximal value 90¸100mV/K for wires with d£200nm. The power factor in this temperaturerange has a plateau and makes up 8.5*10^-5W/cm*K².

Let us note that theSeebeck coefficient in the temperature range 150-60K is positive and the powerfactor is practically constant value.

This work is supported by Civilian Research andDevelopment Foundation for the Independent States of the Former Soviet Union(CRDF) # MP2 – 3019.