Preparation and thermoelectric properties of CoSb/sub 3/ thin films on GaAs(100) substrate

Abstract

The thin film growth of CoSb, on a semi-insulating GaAs(100) substrate was made by using magnetron If-sputtering, and the electrical and thermoelectric properties of the films were studied with relation to annealing temperature and film thickness. Polycrystalline films with the skutterudite structure were successfully grown on the GaAs(100) substrate. The obtained films were found to be p-type, and their hole mobility, electrical conductivity, and Seebeck coefficient significantly changed depending on the annealing temperature and the thickness. A huge Seebeck coefficient of 600 pV/K, which is about three times as large as the value of ap-type single crystal, was obtained for a thin film annealed at 750 "C with thickness of 71 nm, and the power factor reached the value of 2X 10" W/cmK2. The variation in the thermoelectric properties with the annealing temperature and the thickness can be explained well in terms of a model which takes into account a carrier energy filtering effect by potential barriers at grain boundaries. According to the model, the Seebeck coefficient increases with increasing potential barrier height and also decreases with increasing carrier concentration.

Thermoelectric properties of DC-sputtered filled skutterudite thin film

“…However, for 130 nm thin film (Y6) sample, the Seebeck coefficient starts to decrease around 600 K which may due to the carrier energy filtering effect that has been caused by the potential barriers at grain boundaries. 21 The fact that the Seebeck coefficient is negative in Fig. 5 indicates that Yb doped CoSb 3 thin film is an n-type semiconductor, which also agrees with the Hall Effect measurement.…”

“…(1). In fact, 1020 K heat treatment (Y4) fully crystallizes the sputtered thin film 21 and more importantly has large carrier mobility. As a result, from now on an annealing temperature of 1020 K heat treatment will be used for our work.…”

“…Thermoelectric modules based on thin film skutterudite material are still under laboratory research level. 18,19 Anno et al 20,21 reported the grown of CoSb 3 thin film on Si(100) and GaAs (100) substrate using rf-sputtering. In another study, Savchuk et al 22 studied the structural, electrical, and thermal properties of binary skutterudite CoSb 3 thin films deposited using sputtering.…”

Structural properties of thermoelectric CoSb3 skutterudite thin films prepared by molecular beam deposition

“…For instance, thin film techniques deliver several methods to decouple the coefficients and to enhance ZT [1][2][3][4][5][6][7][8][9]. Additionally new material groups like skutterudites with special crystal structure were found [10,11].…”

“…In literature several publications for skutterudite thin films prepared via sputtering [7,[14][15][16], pulsed laser deposition (PLD) [17][18][19][20] or modulated elemental reactant method (MERM) [21][22][23][24] can be found, but all of them describe films thicker than 70 nm, which is in a range, where the benefits due to nanosize effects are limited. Many difficulties are reported in these works for achieving single-phase films, especially for film deposition on heated substrates.…”