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Title: Investigation on the electrical properties and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature

Abstract

A study of the electrical properties and spatial distribution of the ZnO:Al (AZO) thin films prepared by dc magnetron sputtering at low deposition temperature was presented, with emphasis on the origin of the resistivity inhomogeneity across the substrate. Various growth conditions were obtained by manipulating the growth temperature T{sub S}, total pressure P{sub T}, and ion-to-neutral ratio J{sub i}/J{sub n}. The plasma characteristics such as radial ion density and floating/plasma potential distribution over the substrate were measured by Langmuir probe, while the flux and energy distribution of energetic species were estimated through Monte Carlo simulations. The crystalline, stress and electrical properties of the films were found to be strongly dependent on T{sub S} and J{sub i}/J{sub n}. Under the low J{sub i}/J{sub n} (<0.3) conditions, the T{sub S} exerted a remarkable influence on film quality. The films prepared at 90 deg. C were highly compressed, exhibiting poor electrical properties and significant spatial distribution. High quality films with low stress and resistivity were produced at higher T{sub S} (200 deg. C). Similarly, at lower T{sub S} (90 deg. C), higher J{sub i}/J{sub n} ({approx}2) dramatically improved the film resistivity as well as its lateral distribution. Moreover, it indicated that the rolemore » of ion bombardment is dependent on the mechanism of dissipation of incident species. Ion bombardment is beneficial to the film growth if the energy of incident species E{sub i} is below the penetration threshold E{sub pet} ({approx}33 eV for ZnO); on the other hand, the energy subimplant mechanism would work, and the bombardment degrades the film quality when E{sub i} is over the E{sub pet}. The energetic bombardment of negative oxygen ions rather than the positives dominated the resistivity distribution of AZO films, while the nonuniform distribution of active oxygen played a secondary role which was otherwise more notable under conditions of lower T{sub S} and J{sub i}/J{sub n}.« less

Authors:
; ; ;  [1]
  1. Division of Surface Engineering of Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)
Publication Date:
OSTI Identifier:
20884979
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 1; Other Information: DOI: 10.1063/1.2407265; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM; COMPUTERIZED SIMULATION; CRYSTAL GROWTH; ELECTRIC CONDUCTIVITY; ENERGY SPECTRA; ION BEAMS; ION DENSITY; LANGMUIR PROBE; MONTE CARLO METHOD; OXYGEN; OXYGEN IONS; PLASMA POTENTIAL; SEMICONDUCTOR MATERIALS; SPATIAL DISTRIBUTION; SPUTTERING; STRESS ANALYSIS; SUBSTRATES; SURFACE COATING; THIN FILMS; ZINC OXIDES

Citation Formats

Zhang, X. B., Pei, Z. L., Gong, J., and Sun, C.. Investigation on the electrical properties and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature. United States: N. p., 2007. Web. doi:10.1063/1.2407265.
Zhang, X. B., Pei, Z. L., Gong, J., & Sun, C.. Investigation on the electrical properties and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature. United States. doi:10.1063/1.2407265.
Zhang, X. B., Pei, Z. L., Gong, J., and Sun, C.. Mon . "Investigation on the electrical properties and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature". United States. doi:10.1063/1.2407265.
@article{osti_20884979,
title = {Investigation on the electrical properties and inhomogeneous distribution of ZnO:Al thin films prepared by dc magnetron sputtering at low deposition temperature},
author = {Zhang, X. B. and Pei, Z. L. and Gong, J. and Sun, C.},
abstractNote = {A study of the electrical properties and spatial distribution of the ZnO:Al (AZO) thin films prepared by dc magnetron sputtering at low deposition temperature was presented, with emphasis on the origin of the resistivity inhomogeneity across the substrate. Various growth conditions were obtained by manipulating the growth temperature T{sub S}, total pressure P{sub T}, and ion-to-neutral ratio J{sub i}/J{sub n}. The plasma characteristics such as radial ion density and floating/plasma potential distribution over the substrate were measured by Langmuir probe, while the flux and energy distribution of energetic species were estimated through Monte Carlo simulations. The crystalline, stress and electrical properties of the films were found to be strongly dependent on T{sub S} and J{sub i}/J{sub n}. Under the low J{sub i}/J{sub n} (<0.3) conditions, the T{sub S} exerted a remarkable influence on film quality. The films prepared at 90 deg. C were highly compressed, exhibiting poor electrical properties and significant spatial distribution. High quality films with low stress and resistivity were produced at higher T{sub S} (200 deg. C). Similarly, at lower T{sub S} (90 deg. C), higher J{sub i}/J{sub n} ({approx}2) dramatically improved the film resistivity as well as its lateral distribution. Moreover, it indicated that the role of ion bombardment is dependent on the mechanism of dissipation of incident species. Ion bombardment is beneficial to the film growth if the energy of incident species E{sub i} is below the penetration threshold E{sub pet} ({approx}33 eV for ZnO); on the other hand, the energy subimplant mechanism would work, and the bombardment degrades the film quality when E{sub i} is over the E{sub pet}. The energetic bombardment of negative oxygen ions rather than the positives dominated the resistivity distribution of AZO films, while the nonuniform distribution of active oxygen played a secondary role which was otherwise more notable under conditions of lower T{sub S} and J{sub i}/J{sub n}.},
doi = {10.1063/1.2407265},
journal = {Journal of Applied Physics},
number = 1,
volume = 101,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Superconducting thin films of the Bi-Sr-Ca-Cu-O system with and without lead doping were prepared by rf magnetron sputtering onto (100)MgO substrates. Although the superconducting properties of the thin films are very sensitive to the deposition and soak temperatures, reproducible results were obtained. Our {ital in} {ital situ} deposition process with processing temperatures not exceeding 600 {degree}C yielded films with zero resistance at 82 K and {ital J}{sub {ital c}}=7{times}10{sup 5} A cm{sup {minus}2} measured at 4 K for the two-layer Bi phase. Our initial results with lead-doped Bi-Sr-Ca-Cu-O thin films will also be discussed.
  • Transparent conductive ZnO:Al thin films were successfully deposited on glass substrates via radio frequency sputtering with a ceramic target in ambient argon. X-ray diffraction, profilometry, Hall-effect measurement, and spectrophotometry were employed to investigate the structural, electrical, and optical properties of films. The electrical and optical properties were found to be strongly dependent on the crystalline quality, grain size, and thickness of the films. X-ray diffraction spectra indicated that the crystalline quality of the films improved and grains became larger with increasing substrate temperature. Transmission spectra revealed that films possessed a higher transmittance in the visible range with an increase ofmore » the substrate temperature, but the band gap did not broaden obviously. Films with a resistivity of about 2.66 x 10{sup -4}{Omega} cm and an average transmittance above 90% in the visible range were obtained at the optimum temperature of 450 deg. C.« less
  • In this article, Ga-doped Al-zinc-oxide (GAZO)/titanium-doped indium-tin-oxide (ITIO) bi-layer films were deposited onto glass substrates by direct current (dc) magnetron sputtering. The bottom ITIO film, with a thickness of 200 nm, was sputtered onto the glass substrate. The ITIO film was post-annealed at 350 deg. C for 10-120 min as a seed layer. The effect of post-annealing conditions on the morphologies, electrical, and optical properties of ITIO films was investigated. A GAZO layer with a thickness of 1200 nm was continuously sputtered onto the ITIO bottom layer. The results show that the properties of the GAZO/ITIO films were strongly dependentmore » on the post-annealed conditions. The spectral haze (T{sub diffuse}/T{sub total}) of the GAZO/ITIO bi-layer films increases upon increasing the post-annealing time. The haze and resistivity of the GAZO/ITIO bi-layer films were improved with the post-annealed process. After optimizing the deposition and annealing parameters, the GAZO/ITIO bi-layer film has an average transmittance of 83.20% at the 400-800 nm wavelengths, a maximum haze of 16%, and the lowest resistivity of 1.04 x 10{sup -3}{Omega} cm. Finally, the GAZO/ITIO bi-layer films, as a front electrode for silicon-based thin film solar cells, obtained a maximum efficiency of 7.10%. These encouraging experimental results have potential applications in GAZO/ITIO bi-layer film deposition by in-line sputtering without the wet-etching process and enable the production of highly efficient, low-cost thin film solar cells.« less
  • Graphical abstract: - Highlights: • Ni–Al co-doped ZnO (NiAl:ZnO) composite thin films were deposited by DC magnetron sputtering at room temperature. • All films showed a highly preferential (0 0 2) c-axis orientation. • XPS revealed the presence of metallic Ni, NiO, and Ni{sub 2}O{sub 3} states, and Ni atoms were successfully doped in the NiAl:ZnO films. • NiAl:ZnO (3 wt% Ni) film showed the lowest electrical resistivity of 2.59 × 10{sup −3} Ω cm. • Band gap widening (4.18 eV) was observed in the NiAl:ZnO films with 5 wt% Ni. - Abstract: Ni–Al co-doped ZnO (NiAl:ZnO) films with fixedmore » Al content at 2 wt% and different Ni contents (2.5, 3, and 5 wt%) were deposited by DC magnetron sputtering in an argon atmosphere at room temperature. X-ray diffraction revealed that all films showed a highly preferential (0 0 2) c-axis orientation. XPS revealed the presence of metallic Ni, NiO, and Ni{sub 2}O{sub 3} states, and Ni atoms were successfully doped in NiAl:ZnO films, which did not result in a change in ZnO crystal structure and orientation. The electrical resistivity of NiAl:ZnO film was decreased to 2.59 × 10{sup −3} Ω cm at a Ni doping concentration of 3 wt% compared with undoped Al-doped ZnO film (5.58 × 10{sup −3} Ω cm). The mean optical transmittance in the visible range was greater than 80% for all films. Band gap widening (4.18 eV) was observed in the NiAl:ZnO films with 5 wt% Ni, attributed to the Burstein–Moss shift due to the increase of carrier concentration.« less