Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)
Understanding how the defects interact with each other and affect the properties of ZnO:Al films is very important for improving their performance as a transparent conductive oxide (TCO). In the present work, we studied the effects of hydrogen annealing on the structural, optical and electrical properties of ZnO:Al films prepared by magnetron sputtering. High resolution transmission electron microscopy observations reveal that annealing at ∼300 {sup o}C induces the formation of partial dislocations (PD) and stacking faults (SF), which disrupt the lattice periodicity leading to decreased grain size. Annealing at temperatures above ∼500 {sup o}C can remove the PD and SF, but large number of zinc vacancies will be generated. Our results show that when films are annealed at ∼500 {sup o}C, the oxygen-related defects (interstitials O{sub i}, etc.) in the as-grown films can be remarkably removed or converted, which lead to increments in the carrier concentration, mobility, and the transmittance in the visible range. At annealing temperatures above 550 {sup o}C, the hydrogen etching effect becomes predominant, and Al donors are deactivated by zinc vacancies. We also find an abnormal endothermic process by thermal analysis and an abnormal increase in the resistivity during heating the sample under hydrogen atmosphere, based on which the interaction of O{sub i} with the defects (mainly Al donors and PD) is discussed. It is also demonstrated that by annealing the as-grown AZO films at ∼500 {sup o}C under hydrogen atmosphere, high performance TCO films with a low resistivity of 4.48 × 10{sup −4} Ωcm and high transmittance of above 90% in the visible light are obtained.
- OSTI ID:
- 22611527
- Journal Information:
- AIP Advances, Vol. 6, Issue 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2158-3226
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ADDITIONS
ANNEALING
CONCENTRATION RATIO
DEFECTS
DISLOCATIONS
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
GRAIN SIZE
HEATING
INTERSTITIALS
MAGNETRONS
OPACITY
PERIODICITY
RESOLUTION
STACKING FAULTS
THERMAL ANALYSIS
TRANSMISSION ELECTRON MICROSCOPY
ZINC OXIDES