Affected annealing time treatment on preferred orientation and thermoelectric properties of h–GeSbTe0.5 alloy thin film

Abstract

GeSbTe0.5 hexagonal phase thin film (h–GeSbTe0.5) has been deposited on silicon wafer with 1 μm thick silicon dioxide (SiO2/Si) by pulsed dc magnetron sputtering using a 99.99% of 1: 1: 1 ratio of Ge: Sb: Te target at ambient temperature. The as–deposited thin film has been deposited time for 60 min and annealed at temperature 673 K each for 15, 30, 45 and 60 min at high vacuum state. The effected annealing time treatment (ta) on phase preferred orientation, morphology and film thickness (d), atomic composition, carrier concentration (n) and mobility (μ) and Seebeck coefficient have been investigated by X–ray diffraction (XRD), field–emission scanning electron microscopy (FE–SEM), Auger electron microscopy (AES), Hall Effect measurement and steady state method, respectively. The obtained results of as–deposited thin film is amorphous with Ge:Sb:Te; 1:0.7:0.5 atomic ratio and showed the crystal phases of hexagonal structure with Ge:Sb:Te; 1:1:0.5 atomic ratio after annealing at 673 K. The annealed time 45 min of h–GeSbTe0.5 thin film was yielded good thermoelectric properties with highest carrier concentration 3.35 × 1021 cm−3, Seebeck coefficient 78.50 μV K−1and power factor 3.95 × 10−4 Wm−1 K−2.