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

Journal Article · Mon Jan 01 00:00:00 EST 2007 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2407265· OSTI ID:20884979

Zhang, X B; Pei, Z L; Gong, J; Sun, C ^[1]

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1. Division of Surface Engineering of Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

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}.

• OSTI ID: 20884979
• Journal Information: Journal of Applied Physics, Vol. 101, Issue 1; Other Information: DOI: 10.1063/1.2407265; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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