Electrical and optical properties of Zn–In–Sn–O transparent conducting thin films (original) (raw)
Related papers
Annealing of ZnO and SnO2 transparent conductive oxides
Renewable Energy and Power Quality Journal, 2011
Transparent Conductive Oxide (TCO) are used in different field [1], especially as antireflective layers on the surface of solar cells [2,3].But in the solar cells process, annealing steps are often used , i.e ; the front metallic contacts of solar cells are obtained by serigraphy at high temperature (800-830°C). In this case what happen in TCOs used as antireflective layers ?. In this work we present the comparison of changes in physical properties of two TCOs: tin oxide SnO2 and zinc oxide ZnO when they are annealed at low and high temperatures. These films are deposited by the Atmospheric Pressure Chemical Vapour Deposition APCVD technique. Tin oxide is deposited from tin dichloride (SnCl2, 2H 2 O) precursor and zinc oxide is obtained by the use of zinc acetylacetonate Zn(C 5 H 7 O 2)2. The electrical and optical properties of tin oxide and zinc oxide are determined by the four points probes method and spectrophotometry measurement. The values of the resistivity of tin oxide and zinc oxide are 10-4 Ω.cm and 10-3 Ω.cm respectively. These films present an optical transmission higher than 80%. The scanning electronic microscopy images show that the films have a polycrystalline aspect. A post annealing of these TCOs at 450°C improves their electrical properties, while an annealing at higher temperature damage them.
Physical Properties of Sputtered Indium-doped ZnO Films Deposited on Flexible Transparent Substrates
Materials Research
Indium-doped zinc oxide (IZO) polycrystalline thin films were grown on polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and as reference on 7059 Corning glass substrates at room temperature by radio frequency magnetron sputtering from a target prepared with a mixture of ZnO and In 2 O 3 powders. The structural, optical, and electrical properties of the films were analyzed and compared. The IZO polycrystalline films showed n-type conductivity. The electrical resistivity drops significantly, and the carrier concentration increases as a consequence of In incorporation within the ZnO crystalline lattice. In both cases the changes are of several orders of magnitude. The resistivity obtained was 3.1 ± 0.5 x 10-3 Ω-cm for an IZO sample grown on PET with a carrier concentration of 3.1 ± 0.7 x 10 20 cm-3 , the best mobility obtained was 27.7 ± 0.8 cm 2 V-1 s-1 for an IZO sample grown on PEN. From the results, we conclude that n-type IZO polycrystalline films with high transmittance, high mobility and low resistivity were obtained on flexible transparent substrates.
ZnO Thin Film Deposition for TCO Application in Solar Cell
ZnO is a well known suitable candidate for the Transparent Conducting Oxide (TCO) layer of thin film compound solar cells. In this paper we have discussed the deposition of ZnO thin film on glass substrate by reactive DC magnetron sputtering using Oxygen as a reactive gas. Samples are prepared by varying Oxygen flow rates during the deposition process. After deposition, samples are annealed at 300 oC for 2 hours in vacuum environment. All the properties of the film are measured before and after annealing. All the samples are tested for the optical transparency, band gap and electrical resistivity before and after annealing. Band gap of film is observed 3.2 eV. XRD and SEM measurements of the samples show the variation in the crystal structure and surface morphology of the film with varying oxygen flow rate and annealing also. Around 600 nm thick ZnO film with 1.5x10-3 Ω-cm resistivity and 80% transparency without any doping is achieved.
Low temperature Si doped ZnO thin films for transparent conducting oxides
Solar Energy Materials and Solar Cells, 2011
Si doped zinc oxide (SZO, Si 3%) thin films are grown at low substrate temperature (Tr 150 1C) under oxygen atmosphere, using pulsed laser deposition (PLD). Si addition leads to film amorphization and higher densification. Hall effect measurements indicate a resistivity of 7.9 Â 10 À 4 O cm for SZO thin films deposited at 100 1C under optimized 1.0 Pa oxygen pressure. This value is in good agreement with optical resistivity simulated from the transmittance spectra. XPS measurements suggest more than one oxygen environment, and a Si oxidation state lying in between 2 and 3 only. As a matter of fact, the values of both measured and simulated carrier numbers are smaller than the ones expected, assuming that all Si cations in the ZnO matrix are at the 4 þ oxidation state. Finally, the differences in the electrical and optical properties of SZO thin films deposited both on glass and PET substrates confirm the strong dependency of the electronic properties to the film crystallinity and stoichiometry in relationship with the substrate nature.
THIN FILM DEPOSITION OF TRANSPARENT CONDUCTIVE OXIDES FOR SOLAR CELL APPLICATION
The present study reports on the physical properties, status, prospects for further development, and applications of polycrystalline or amorphous, transparent, and conducting oxides (TCO) semiconductors. The coexistence of electrical conductivity and optical transparency in these materials depends on the nature, number, and atomic arrangements of metal cations in crystalline or amorphous oxide structures, on the resident morphology, and on the presence of intrinsic or intentionally introduced defects. The important TCO semiconductors are impurity-doped ZnO, In2O3, SnO2 and CdO, as well as the ternary compounds Zn2SnO4, ZnSnO3, Zn2In2O5, Zn3In2O6, In2SnO4, CdSnO3, and multi-component oxides consisting of combinations of ZnO, In2O3 and SnO2. Sn doped In2O3 (ITO) and F doped SnO2 TCO thin films are the preferable materials for most present applications. The expanding use of TCO materials, especially for the production of transparent electrodes for optoelectronic device applications, is endangered by the scarcity and high price of In. This situation drives the search for alternative TCO materials to replace ITO. The electrical resistivity of the novel TCO materials should be ~10-5 Ω.cm, typical absorption coefficient smaller than 104 cm-1 in the near UV and visible range, with optical band gap ~3 eV. At present, ZnO:Al and ZnO:Ga (AZO and GZO) semiconductors could become good alternatives to ITO for thin-film transparent electrode applications. The best candidates are AZO thin films, which have low resistivity of the order of 10−4Ω.cm, inexpensive source materials, and are non-toxic. However, development of large area deposition techniques are still needed to enable the production of AZO and GZO films on large area substrates with a high deposition rate. In addition to the required electrical and optical characteristics, applied TCO materials should be stable in hostile environment containing acidic and alkali solutions, oxidizing and reducing atmospheres, and elevated temperature. Most of the TCO materials are n-type semiconductors, but p-type TCO materials are researched and developed. Such TCO include: ZnO:Mg, ZnO:N, IZO, NiO, NiO:Li, CuAlO2, Cu2SrO2, and CuGaO2 thin films. At present, these materials have not yet found place in actual applications.
Structural, electrical and transparent properties of ZnO thin films prepared by magnetron sputtering
Current Applied Physics, 2004
Zinc oxide (ZnO) thin films were prepared by d.c. (direct current) or r.f. (radio frequency) magnetron sputtering on glass substrates. The structural, electrical and optical properties of the films were studied. It has been found that most films produced by d.c. sputtering are not electrically conductive or have a high resistance above 10 X m, while the films produced using r.f. sputtering are significantly more conductive. The optical transmittance at 550 nm is around 80% or higher for most films. The energy band gaps of the ZnO films prepared by d.c. sputtering are smaller than the films prepared by r.f. sputtering. It is also found that the films prepared using an electrical bias have higher resistivity than those produced without bias. It has been observed by SEM that the conductive films show less porosity between the grains than the poor conductive films. Conductive ZnO films show a smaller d spacing than the non-conductive films. The results reveal that crystal microstructure and density of the ZnO films affect their conductivity.
Science and Technology Development Journal, 2019
Introduction: ZnO-based thin films, known as potential transparent-conducting oxides (TCO), have still attracted much attention in applications for good-performance electrodes and inner layers in solar cells. Recently, the research tendency has focused on improving carrier mobility rather than carrier concentration to enhance performance and response speed of TCO thin films. In this work, Indium, and Hydrogen co-doped ZnO (HIZO) thin films were deposited by using DC magnetron sputtering technique in hydrogen-plasma atmosphere. Methods: Indium-doped ZnO ceramics were used as sputtering targets, in which, Indium content varied from 0.07 to 1.0 at.%. The electrical, optical, structural and surface morphological properties of the as-deposited films were investigated by using Hall effect-based measurement, UV-Vis spectra, X-ray diffraction (XRD) and fieldemission scanning electron microscopy (FE-SEM), respectively. Results: As a result, the HIZO films sputtered from the 0.1 at.% In-doped...