Very Smooth FeSb2Te and Ce0.1Fe0.7Co3.3Sb12 Layers Prepared by Modified PLD

Abstract

We report on the preparation of thermoelectric layers of FeSb2Te and Ce0.1Fe0.7Co3.3Sb12 on silicon (100) and fused silica substrates via a combination of pulsed laser deposition (PLD) and rapid thermal annealing methods. A wide range of deposition conditions were tested including on- and off-axis approaches and variation of the annealing temperature profile. Wavelength dispersive x-ray spectroscopy was used to determine stoichiometry. An optical microscope, mechanical profilometer, and atomic force microscopy served to map layer topology. For the FeSb2Te layers, Sa was between 1.4 nm and 6 nm, with Sq ranging from 2.1 nm to 7.8 nm. For Ce0.1Fe0.7Co3.3Sb12 layers, Sa was from 1.3 nm to 4.2 nm and Sq between 1.7 nm and 6.2 nm. Crystalline structure was determined by x-ray diffraction. The best layers (in terms of smooth surface and crystalline structure) prepared using a modified off-axis PLD arrangement were then characterized for thermoelectric properties. The smooth, stoichiometric and crystalline layers of both types were prepared at an annealing temperature of 423 K for 10 min. All experiments were conducted with the aim of finding the deposition condition providing smooth and crystalline layers. These conditions should be used for the deposition of multilayered systems composed of the FeSb2Te and Ce0.1Fe0.7Co3.3Sb12 layers with a period of about 1 nm, where there could be layer roughness comparable to the period.