Sn Doped ZnO Thin Films Research Articles

Study on the doping effect of Sn-doped ZnO thin films

Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto Pyrex glass substrates by chemical spray pyrolysis technique starting from zinc acetate (CH3CO2)2Zn⋅2H2O and tin chloride SnCl2. The effect of Sn doping on structural, optical and electrical properties was investigated. The atomic percentages of dopant in ZnO-based solution were y=[Sn4+]/[Zn2+]=0%, 0.2%, 0.6% and 1%. It was found that all the thin films have a preferential c-axis orientation. With increase of Sn doping, the peak position of the (002) plane was shifted to the high 2θ values. ZnO:Sn demonstrated obviously improved surface roughness, reduced average crystallite size, enhanced Hall mobility and reduced resistivity. Among all of the tin doped zinc oxide in this study, films doped with 0.6at.% Sn concentration exhibited the best properties, namely a Hall mobility of 9.22cm2V−1s−1, an RMS roughness of 37.15nm and a resistivity of 8.32×10−2Ωcm.

Effects of Co and/or Sn doping on crystal structures and optical properties of ZnO thin films

The Co and/or Sn doped ZnO thin films are deposited on the glass substrates by the sol-gel method. The effects of Co and/or Sn doping on surface morphologies and mircrostructures of ZnO films are investigated by metallurgical microscope and X-ray diffraction (XRD). The XRD results indicate that all the ZnO samples show preferential orientation along the (002) direction, and that the Sn-doped ZnO thin film exhibits the best c-axis orientation and largest grain size. XPS results reveal that Co and Sn elements exist as Co2+ and Sn4+, indicating that Co and Sn ions have entered into the ZnO crystal lattices successfully. Strong blue double emission and weak green emission are observed in the PL spectra of all the samples. In addition, the ultraviolet peaks appear in the undoped and the Co-doped ZnO thin films. Our results reveal that the Co and/or Sn doping can tune the band gap, meanwhile, such a doping can also affect oxygen dislocation, zinc oxygen and zinc interstial defect concentrations. Finally, the possible luminescence mechanisms of Co and/or Sn doped ZnO films are discussed.

Surface Characteristics, Optical and Electrical Properties on Sol-Gel Synthesized Sn-Doped ZnO Thin Film

Un-doped ZnO and Sn-doped ZnO (SZO) thin films were synthesized using the sol-gel method. The surface morphology of the SZO films showed a large amount of crystallization. Doping with tin dopants not only reduced the surface roughness of the film, but also repaired defects in the pore structure. Notably, the SZO film with a crystallization temperature of 650°C possessed better crystallization and fewer defects when tin dopants were added. XPS analysis confirmed the presence of O-Sn4+ phases proving the contribution of tin doping on the electrical conductivity of the SZO films. With regards the PL spectra, luminescence in the Zn2SnO4 phase was observed and affected the red-shifted of broad visible emission. In addition, the 9 at% Sn doped ZnO (S9ZO) film showed excellent optical transmittance, however the transmittance improved further when the trace of tin dopants (0.4 at%) and 2 at% In were doped in ZnO matrix (I2S0.4ZO).

Crystalline structure and morphological properties of undoped and Sn doped ZnO thin films

Undoped and tin (Sn) doped ZnO thin films have been prepared by spray pyrolysis method. Effect of Sn dopant on the crystalline structure and morphological properties of ZnO thin films has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) method. XRD patterns confirm that the films have polycrystalline nature. While undoped ZnO film has (101) as the preferred orientation, Sn doped ZnO thin films have (002) as the preferred orientation. Grain sizes, lattice parameters and texture coefficient values of the films were determined. Microstructure was analyzed by SEM and the influence of the doping concentration in the microstructure of the films is investigated.

Investigation of the Characteristics of Undoped and Sn-Doped ZnO Films Prepared by an Acidic Sol

Transparent conducting thin films of undoped and Sn-doped zinc oxide films were prepared on glass substrate by a dip-coating method using an acidic sol. The effect of metal sources, zinc chloride and zinc acetate dihydrate , on the crystalline structure and properties of the films was investigated in detail. X-ray diffraction analysis reveals that the acidic sol leads to ZnO crystals with a hexagonal wurtzite structure after annealing treatment. Transmission electron microscopy results evidence that the Sn-doped ZnO thin films are a mixed phase of wurtzite ZnO and tetragonal nanocrystals. Field-emission scanning electron microscopy shows that the morphology of the films is largely affected by the zinc metal sources, and optical and electrical properties of the films are closely related to their microstructure. The undoped films prepared with the zinc chloride source exhibit a lower transmittance in the visible wavelength between 600 and , compared with that using the zinc acetate dihydrate source. The electrical resistivity of the undoped films is high but can be reduced by a Sn doping treatment. The optimum electrical resistivity of the Sn-doped films can reach to about .

Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol–gel method

In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol–gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 °C for 10 min and then annealed in air at 500 °C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400–600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 × 10 2 Ω-cm.

Effects of In, Al and Sn dopants on the structural and optical properties of ZnO thin films

Effect of In, Al and Sn dopants on the optical and structural properties of ZnO thin films have been investigated by X-ray diffraction technique and optical characterization method. X-ray diffraction patterns confirm that the films have polycrystalline nature. The thin films have (0 0 2) as the preferred orientation. This (0 0 2) preferred orientation is due to the minimal surface energy which the hexagonal structure, c-plane to the ZnO crystallites, corresponds to the densest packed plane. The grain size values of the films are found to be 29.0, 35.2 and 39.5 nm for In, Al and Sn doped ZnO thin films, respectively. The optical band gaps of the films were calculated. The absorption edge shifts to the lower wavelengths with In, Al and Sn dopants. The inclusion of dopant into films expands also width of localized states as E UIn > E UAl > E USn. The refractive index dispersion curves obey the single oscillator model. The dispersion parameters and optical constants of the films were determined. These parameters changed with In, Al and Sn dopants.

Growth and characterization of Sn doped ZnO thin films by pulsed laser deposition

AbstractSn:ZnO thin films with different Sn concentrations were grown by pulsed laser deposition (PLD) onto single‐crystal Si(001) substrates at an oxygen pressure of 2 × 10–2 mbar and substrate temperature of 600 °C. The targets used were high density Sn:ZnO pellets with different Sn concentrations produced by mixing ZnO and SnO2 by conventional ceramic routes. A deep structural and electrical characterization was carried out in order to determine the role of an increasing Sn nominal concentration on the ZnO film transport properties. Only films with a nominal 0.1 at% Sn show an improvement of the transport properties, lower resistivity and higher donor concentration, with respect to pure ZnO thin films. For films with larger Sn nominal concentrations segregated SnZnO phases appear that lead to larger film resistivities and no increase in donor concentration. The 0.1 at% Sn film is accordingly a good candidate to study the possible room temperature ferromagnetism when co doping with Mn. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)