Experimental and theoretical study of thermoelectric properties of rhombohedral GeSb5Te10 thin films.

Rhombohedral GeSb 5 Te 10 thin films are synthesized onto Al 2 O 3 substrate by a pulsed-DC magnetron sputtering method using a target prepared by hot-pressing method. Thermoelectric properties of these films are studied as a function of temperature from room temperature to 773 K and correlated to the microstructural and surface properties. It is found that the phase transformation from amorphous to rhombohedral phase of GeSb 5 Te 10 , observed in temperature range 473–773 K, involved lattice-swelling and atomic diffusion within the crystalline structure. The completion of phase transformation at annealing temperature 673 K minimized the average crystallite size of thin film and enhanced the Seebeck coefficients (~140 μVK−1) and thermoelectric power factor (~4.5 mWm−1 K−2). Molecular orbital simulations of small cluster model, performed using linearly decreasing scattering variable along with the temperature dependent Fermi energy for onto determining the electrical and thermoelectric properties, were found in agreement to the experimental results. [ABSTRACT FROM AUTHOR]