Zhuang Hao Zheng

Influence of Sputtering Power of Te and Annealing on Sb-Te Thin Films Fabricated by RF and DC Co-Sputtering

Antimony and tellurium were deposited on K9 glass via direct current and radio frequency magnetron co-sputtering. Antimony telluride thermoelectric thin films were simultaneously synthesized without post treatment. The influence of the sputtering power of Te and annealing of Sb-Te fabricated by magnetron sputtering were investigated. The maximum Seebeck coefficient of Sb-Te film was 212 μV/K which was obtained at the sputtering power of Sb 4W and Te 60W separately. When annealed at 300 °C, the electrical resistivity and Seebeck coefficient of the film are 6.67x104 S/m and 119 μV/K. The power factor increased to the highest value of 9.4×10-4 W/mK2 from 4×10-5 W/mK2 after post treatment of the as-deposited film.

Thermoelectric Properties of Al Doped ZnO Thin Films

Significant progress has been made in thermoelectric materials during the last decades and it is found that thermoelectric thin film materials have high thermoelectric conversion efficiency. ZnO based thermoelectric materials, such as ZnO:Al (AZO), are considered as the most promising oxide materials for high-temperature, nontoxic and low-cost thermoelectric application. In this work, the effects of annealing temperature on the thermoelectric properties of AZO thin films prepared by direct current magnetron sputtering were investigated. The results indicate that the Seebeck coefficient of AZO thin films increases and the resistivity decreases as increasing of annealing temperature. Among the prepared AZO films in this work, the maximum absolute value of Seebeck coefficient is 460 μV/K and the minimum resistivity is 3.25×10-4 Ω·m. The sample annealed at 773 K has a maximum power factor value of 1.46×10-4 W/mK2 at 620 K with a moderate Seebeck coefficient of-355 μV/K and a electrical conductivity of 1.16×103 S/m.

Thermoelectric Characterization of Direct Current Magnetron Co-Sputtering Zinc Antimonide Thin Films

Direct current magnetron co-sputtering was used to deposit zinc antimonide thin films on BK7 glass substrates at room-temperature. Then the films were annealed at 573 K to 673 K for 1 hour in Ar atmosphere. The results indicate that the Seebeck coefficient of the thin films increase from 30.5 μVK-1to 132.5 μVK-1 when the annealing temperature changed. The electrical conductivity of the thin films increases from 3.45×103 to 6.86×103 Sm-1 and the Power Factor is enhanced greatly from 0.03×10-4 to 0.99×10-4 Wm-1K-2 when the annealing temperature reached 598 K. X-ray diffraction result shows that the major diffraction peaks of the thin films match those of β phase Zn4Sb3 and high crystalline thin films are achieved after annealing.

Room Temperature Deposition and Properties of AZO Thin Films by DC Magnetron Sputtering under Different Plasma Power

To evaluate the influence of plasma power on the structural, electrical and optical properties of Al-doped ZnO (AZO) films, a set of polycrystalline AZO samples under different plasma power were deposited on glass substrates at room temperature. X-ray diffraction technique (XRD), four-point probe measurements and spectrophotometer were used to characterize these films. XRD shows that all AZO films have a hexagonal wurtzite structure with prominent (002) orientation. With the plasma power increasing, the grain size first increases and then decreases. The largest grain size of 23.6 nm in the films is obtained at the plasma power of 123 W. The average optical transmittance of AZO films is over 80% in the visible region. The lowest resistivity of 1.0×10-3Ω•cm is obtained under the plasma power of 220 W.

Dependence of Negative Substrate Bias on the Optical and Electrical Properties of W-Doped Vanadium Dioxide Thin Films

W-doped VO2 films were prepared by DC reactive magnetron sputtering with various substrate bias. The microstructure, surface morphology, electrical and optical performances of the films were characterized by x-ray diffraction, scanning electron microscope, four-point probe method and spectrophotometer, respectively. The effect of substrate bias on microstructure, electrical and optical properties of sputtered W-doped VO2 films was studied. The XRD results reveal that all samples exhibit preferential VO2 (011) lattice orientation except the as-grown sample in our experiment. All the samples applied substrate bias show some degree optical switching performance in IR range, while the thermochromic phenomena was observed from resistance-temperature dependence plot only for the samples of substrate bias varied from-100V to-200V. This indicate that the optical and electrical properties of W-doped VO2 films have different sensitivity to substrate bias. Optimal substrate bias of-200V sample shows fine semiconductor-metal-transition performance.

Thermoelectric Properties of β-Zn4Sb3 Thin Films Deposited on Polyimide Flexible Substrate

Due to the high-performance in the medium temperature application, β-Zn4Sb3 thermoelectric material has been received much attention. It is found that low dimensional thin film can improve the thermoelectric properties of materials by quantum local area effect and interface effect in recent years. In this paper, the β-Zn4Sb3 thin film was prepared on polyimide flexible substrate by DC magnetron co-sputtering method. The results showed that the thin film exhibited predominately ZnSb phases when the thin film was prepared by DC magnetron sputtering using Zn4Sb3 alloy target. It is suggested that the element Zn has high saturated vapor pressure and the thin film is lack of Zn due to the evaporation during the heat treatment process. We further adopted co-deposition Zn and Zn4Sb3 by DC magnetron co-sputtering to supplement the content of Zn. The sputtering power of Zn4Sb3 is fixed and Zn is set to 21W, 27W and 34W, respectively. The results indicated that the thin films transformed from ZnSb phase into β-Zn4Sb3 phase after Zn added. EDS analysis demonstrated that the atomic ratio of Zn:Sb was approach 4:3, and a slightly surplus of Zn. The thermoelectric properties of thin films with β-Zn4Sb3 phase were improved obviously.

Thermoelectric Characterization of Ti and In Double-Doped Cobalt Antimony Thin Films

CoSb3 thermoelectric thin films were prepared on polyimide flexible substrate by radio frequency (RF) magnetron sputtering technology using a cobalt antimony alloy target. Ti and In were added into CoSb3 thin films by co-sputtering. The influence of Ti and In on the thermoelectric properties of CoSb3 thin films was investigated. X-ray diffraction result shows that the major diffraction peaks of all the thin films match the standard peaks related to the CoSb3 phase. The sample has best thermoelectric properties when the Ti sputtering time was 1min and In sputtering time was 30 seconds.

Ion-Beam Sputtering Deposited Cu-Doped CdS Thin Film

Cu-doped CdS thin film has been successfully deposited by ion-beam sputtering deposition. The structural, morphology, optical and electrical properties of as-deposited and annealed Cu-doped CdS thin films were investigated. The heavily Cu-doped CdS films annealed at 400 °C was demonstrated to be improved in structural, morphology, electrical and optical properties. X-ray diffraction (XRD) analysis indicated the formation of polycrystalline CdS film with the structure of hexagonal wurtzite phase. No distinct impurity of Cu and Cu-S phase was detected in Cu-doped CdS thin films. Atomic force microscopy (AFM) revealed that the grain size was increased after annealed. Optical transmission and absorption spectroscopy measurement revealed a high absorption and energy band gap was of about 2.40 eV. The CdS thin film was of p-type conductivity and the resistivity was found to be 1.28×10-1Ωcm.

Influence of Ti-Doping on the Thermoelectric Properties of ZnO:Al Thin Films

Ti doped aluminum zinc oxide thin film was prepared by DC reaction magnetron sputtering method on the transparent glass substrates. The structure and thermoelectric performance of the deposited (TAZO) thin films are studied by various methods. XRD pattern shows that the TAZO thin film exhibits hexagonal wurtzite structure. After Ti-doping, the thermoelectric properties of TAZO thin film significantly improved at room temperature. The TAZO thin film has the maximum conductivity of 8.33×104 S/m and the Seebeck coefficient absolute value of 34 μV/K, which is respectively larger than that of the corresponding values.

The Characterization of CIGS Thin Films Prepared by Ion Beam Sputtering Deposition from a Quaternary Target

This study reports the successful preparation of Cu (In, Ga)Se2 (CIGS) thin film solar cells by ion beam sputtering with a chalcopyrite CIGS quaternary target. The films were fabricated with different beam currents. The thin films were characterized with X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and hall effect-measurement system to study the microstructures, composition, surface morphology and electrical properties, respectively. Experimental results show that both the films are chalcopyrite structure, the Ga/(In+Ga) ratio, Cu/(In+Ga) ratio and Se/(Cu+In+Ga) ratio are decrease with the beam currents increase, the surfaces morphology of the films are dense, and the resistivity of the film deposited with the beam current of 40mA is 0.56Ωcm, with a carrier concentration of 4.11Χ1018cm-3 and mobility of 2.73cm2V-1s-1. The resulting film exhibited p-type conductivity.