Effect of oxidation on the thermoelectric properties of PbTe and PbS epitaxial films

Abstract

We report on the thickness d dependences of the Seebeck coefficient, electrical conductivity, and Hall coefficient of PbTe and PbS epitaxial thin films (d=5–200 nm), prepared by thermal evaporation in vacuum and deposition on (001) KCl substrates. The oxidation of the films in air at 300 K leads to a sign inversion of the carrier type from n to p in films with d⩽125 and 110 nm for PbTe and PbS, respectively. The observed d dependences are interpreted in terms of compensating acceptor states created by oxygen on the film surface.

Formation of PbTe nanofilms by electrochemical atomic layer deposition (ALD)

“…The higher the figure of merit of a material, the more efficiently it can generate electricity from heat. PbTe is an important thermoelectric material [4][5][6][7][8][9][10][11][12][13][14] due to its high figure of merit, good chemical stability, low vapor pressure and high melting point (∼900 K). PbTe is IV-VI compound semiconductor, with the rock salt structure and a narrow band gap (E g = 0.29 eV).…”

Effect of oxidation on the thermoelectric properties of PbSe thin films

“…The more detailed (compare to Ref. 18) studies of the galvanomagnetic and thermoelectric properties as a function of d that were conducted in the present work allowed us to reveal an extremum behavior of the (d) and (d) dependences in the p region, which we attribute to the transition from a semicontinuous film to a continuous one. It follows from our data that as a result of oxidation in very thin PbSe films, the maximum possible concentrations of p-type charge carriers, which are usually attained in bulk PbSe due to doping (ϳ2 и 10 20 cm Ϫ3 ), can be obtained in thin films through the oxidation mechanism.…”

“…18, we reported the d dependences of the thermoelectric properties in PbTe and PbS thin films prepared by the thermal evaporation of the corresponding crystalline material in a vacuum and its subsequent deposition onto (001) KCl substrates. It was shown that the oxidation of the films in air at 300 K leads to a sign inversion of the carrier type from n-type to p-type in films with d Յ 125 nm and d Յ 110 nm for PbTe and PbS, respectively.…”

“…18 (1) In all three compounds, an inversion of the dominant carrier sign from n-type to p-type occurs as the film thickness decreases below a certain d value. (2) In the p range, an increase in R H is observed.…”

Size effects in p-PbTe nanostructures on polyamide

“…If the investigated object is the ntype condensate, this problem can be solved by film coating protective layer EuS. The authors of [6] have shown that EuS thickness ~30 nm is quite enough to completely avoid the oxygen action. Thus, this protective layer is regarded as one of barriers that creates a quantum well for carriers in PbTe structure.…”