Properties Of Sb2Te3 Thin Films Research Articles

Enhanced Thermoelectric Properties of Sb2Te3 Thin Films by In Doping

Flexible Sb2Te3-based thermoelectric (TE) materials are promising candidates for fabricating energy devices that power wearable electronics and sensors. Enhancing the TE properties of Sb2Te3 thin films represents a significant scientific investigation. In this work, a thermal diffusion method is applied to prepare the In-doped Sb2Te3 thin film. In doping can lead to a high Seebeck coefficient of ~137.04 μV K−1 as well as moderate electrical conductivity. As a result, the high power factor of ~18.22 μW cm−1 K−2 at 303 K is achieved. Moreover, In doping could reduce the thermal conductivity owing to the increase in phonon scattering. Finally, the high ZT values of ~0.47 at room temperature (303 K) and ~0.6 at 453 K are obtained. This indicates that In doping is a highly promising and effective approach to improving the TE performance of Sb2Te3 thin films.

Impact of defects on the structural and electrical transport properties of Sb2Te3 thin films by SHI irradiation

Implantation of defects is an attractive trend for the modification of important properties of thin films for practical applications. In the present attempt, an effective approach for tuning the native defects in thin films is reported. The films were sequentially irradiated at five different fluences (5 × 1011, 1 × 1012, 3 × 1012, 5 × 1012, and 1 × 1013 ions/cm2). The key role of high-energy Ni ion irradiation-induced native defects was observed by the modifications in the physical properties of samples. However, irradiation induces a structural phase transition through strain. The average crystallite size as determined from X-ray diffraction (XRD) peak broadening was found to be 19.3 ± 5 (nm). A monotonic increase in the lattice strain was observed up to a fluence of 5 × 1012 ions/cm2. The resistivity v/s temperature measurements revealed an increase in resistivity up to the fluence 3 × 1012 ions/cm2 indicating an increase in grain boundaries effect. Our findings provide an insight into the correlation of tuned properties with the defects induced by irradiation and also a route to have the defects in a precise and controlled way.

Structural and Morphological Modifications Induced by Fe Ion Implantation in Sb2Te3 Thin Films

AbstractRecently, considerable interest has been initiated by the influence of magnetic dopants as well as the generation of internal strain on the transport properties of topological insulators. The controlled bulk charge carriers in topological insulators help in removing barriers for surface‐dominated transport. In this work, the impact of Fe‐ion implantation on the structural and optical properties of Sb2Te3 thin films is presented. The implantation is done with low energy Fe4– ions at three different fluences (1 × 1013, 1 × 1014, and 5 × 1014 ions cm−2). The structural studies carried out using X‐ray diffraction measurements show that the thin films exhibit rhombohedral structures with an R‐3m space group. A monotonic decrease in the lattice parameter “c” is also observed with increasing ion fluence confirms the contraction in lattice after implantation with ions of smaller radii. The optical studies indicate the structural strain induces by implantation. The incorporated Fe ion affects the grain size, as studied by Atomic Force Microscopy (AFM) measurements. The suppression of grain boundaries towards the highest fluence point is towards a possibility of surface reconstruction.

Tuning of physical properties through implantation mediated Cu doping in Sb2Te3 thin films

The time-reversal symmetry-protected surface states make topological insulators an interesting candidate for the fantastic quantum phenomenon. Nowadays, 3D Topological insulators doped with magnetic elements are becoming a promising area of research in fundamental device applications. The present work aims to investigate the influence of Cu dopants via implantation on the physical properties of Sb2Te3 thin films. Thin films synthesized using the e-beam evaporation technique were implanted with Cu ions at 5 different fluences (1 × 1013, 5 × 1013, 1 × 1014, 5 × 1014, and 1 × 1015ions/cm2). X-ray Diffraction measurements reveal the rhombohedral structure of thin films with an R-3 m space group. The smaller radii of Cu ion embedded in Sb2Te3 thin films could reduce the lattice parameter ‘c’. The ion implantation induced structural strain is also observed in Raman modes as confirmed by optical studies. The Atomic Force Microscopy (AFM) measurements indicate the effect of ion implantation on the granular morphology of thin films. The increase in grain boundaries with implantation indicates the implantation induced damage to the surface. The temperature-dependent resistivity plot suggests the enhancement of the semiconducting behavior of thin films by implantation-induced defects. Our findings provide a route to have modifications in the material in a controlled way.

Enhanced Thermoelectric Properties of Antimony Telluride Thin Films with Preferred Orientation Prepared by Sputtering a Fan-Shaped Binary Composite Target

p-Type antimony telluride (Sb2Te3) thermoelectric thin films were deposited on BK7 glass substrates by ion beam sputter deposition using a fan-shaped binary composite target. The deposition temperature was varied from 100°C to 300°C in increments of 50°C. The influence of the deposition temperature on the microstructure, surface morphology, and thermoelectric properties of the thin films was systematically investigated. x-Ray diffraction results show that various alloy composition phases of the Sb2Te3 materials are grown when the deposition temperature is lower than 200°C. Preferred c-axis orientation of the Sb2Te3 thin film became obvious when the deposition temperature was above 200°C, and thin film with single-phase Sb2Te3 was obtained when the deposition temperature was 250°C. Scanning electron microscopy reveals that the average grain size of the films increases with increasing deposition temperature and that the thin film deposited at 250°C shows rhombohedral shape corresponding to the original Sb2Te3 structure. The room-temperature Seebeck coefficient and electrical conductivity range from 101 μV K−1 to 161 μV K−1 and 0.81 × 103 S cm−1 to 3.91 × 103 S cm−1, respectively, as the deposition temperature is increased from 100°C to 300°C. An optimal power factor of 6.12 × 10−3 W m−1 K−2 is obtained for deposition temperature of 250°C. The thermoelectric properties of Sb2Te3 thin films have been found to be strongly enhanced when prepared using the fan-shaped binary composite target method with an appropriate substrate temperature.

Effects of annealing on thermoelectric properties of Sb2Te3 thin films prepared by radio frequency magnetron sputtering

Antimony telluride (Sb2Te3) thin films were deposited on silicon substrates at room temperature (300 K) by radio frequency magnetron sputtering method. The effects of annealing in N2 atmosphere on their thermoelectric properties were investigated. The microstructure and composition of these films were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction, respectively. The electrical transport properties of the thin films, in terms of electrical conductivity and Seebeck coefficient were determined at room temperature. The carrier concentration and mobility were calculated from the Hall coefficient measurement. Both of the Seebeck coefficient and Hall coefficient measurement showed that the prepared Sb2Te3 thin films were p-type semiconductor materials. By optimizing the annealing temperature, the power factor achieved a maximum value of 18.02 μW cm−1 K−2 when the annealing temperature was increased to 523 K for 6 h with a maximum electrical conductivity (1.17 × 103 S/cm) and moderate Seebeck coefficient (123.9 μV/K).

Structural and thermoelectric transport properties of Sb2Te3 thin films grown by molecular beam epitaxy

We have studied the structural and transport properties of Sb2Te3 thin films prepared by molecular beam epitaxy as a function of the Te/Sb flux ratio during deposition. Both the crystallinity and the transport properties are found to be strongly affected by nonstoichiometry. The most stoichiometric sample (prepared with a Te/Sb ratio of 3.6) had a high degree of crystallinity, high thermopower, and high carrier mobility. However, Sb2Te3 films with excess Sb or Te had poorer crystallinity, reduced magnitude of the thermopower, and reduced mobility as a result of the formation of antisite defects. These antisite defects were able to be reduced by controlling the relative flow rate ratio of Te to Sb during growth.