Publication date: 1 April 2015
Source:Journal of Crystal Growth, Volume 415
Author(s): G. Thankamma , A.G. Kunjomana
A series of p -type Sb2 Te3−x S x (x =0, 0.1, 0.2, 0.3 and 0.4) samples for each sulfur composition was vapor deposited to explore the crystal growth mechanism of platelet morphology and to understand their potential use for thermoelectric devices. Structural characterization performed by X-ray diffraction exhibited consistent rhombohedral unit cell parameters for all the antimony telluride crystals with D5 3d space group symmetry. Scanning electron microscopy (SEM) and energy dispersive analysis by X-rays (EDAX) were employed for morphological and compositional studies. The Seebeck coefficient S (⊥c ) of Sb2 Te3−x S x crystals for sulfur composition, x =0.3 was remarkably improved, yielding a figure of merit (ZT )=0.54, which is ~2.5 fold rise compared to the melt grown Sb2 Te3 crystals. The atomic force microscopic (AFM) imprints revealed that, with increasing content of dopant, distribution of etch pits and microhardness increased in sulfur doped crystals. By optimizing sulfur doping, the antisite (AS) defect formation can be suppressed for enhancing ZT and the results obtained enable to design novel thermoelectric materials for application in power generation and refrigeration.
Source:Journal of Crystal Growth, Volume 415
Author(s): G. Thankamma , A.G. Kunjomana