skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing

Abstract

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, basedmore » 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.« less

Authors:
; ; ; ; ; ;  [1]
  1. Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)
Publication Date:
OSTI Identifier:
22611527
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, 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

Citation Formats

Yin, Shiliu, Shirolkar, Mandar M., Li, Jieni, Li, Ming, Song, Xiao, Dong, Xiaolei, and Wang, Haiqian, E-mail: hqwang@ustc.edu.cn. Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing. United States: N. p., 2016. Web. doi:10.1063/1.4954885.
Yin, Shiliu, Shirolkar, Mandar M., Li, Jieni, Li, Ming, Song, Xiao, Dong, Xiaolei, & Wang, Haiqian, E-mail: hqwang@ustc.edu.cn. Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing. United States. doi:10.1063/1.4954885.
Yin, Shiliu, Shirolkar, Mandar M., Li, Jieni, Li, Ming, Song, Xiao, Dong, Xiaolei, and Wang, Haiqian, E-mail: hqwang@ustc.edu.cn. 2016. "Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing". United States. doi:10.1063/1.4954885.
@article{osti_22611527,
title = {Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing},
author = {Yin, Shiliu and Shirolkar, Mandar M. and Li, Jieni and Li, Ming and Song, Xiao and Dong, Xiaolei and Wang, Haiqian, E-mail: hqwang@ustc.edu.cn},
abstractNote = {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.},
doi = {10.1063/1.4954885},
journal = {AIP Advances},
number = 6,
volume = 6,
place = {United States},
year = 2016,
month = 6
}
  • We report magnetic properties of Y{sub 3}Fe{sub 5}O{sub 12} (YIG) films on thermally oxidized Si (100) and (Gd{sub 3}Ga{sub 5}O{sub 12}) GGG (111) substrates. Amorphous YIG films with the cation ratio Y:Fe=3.04:4.96, deposited by rf-magnetron sputtering at room temperature in pure argon atmosphere, were crystallized by postannealing (600-900 deg. C) of amorphous films in air and in 500 ppm oxygen. While postannealed YIG films on GGG substrates were well textured, those on Si (100) were randomly oriented. High-quality YIG films could be better obtained in the reduced (500 ppm O{sub 2}) oxygen atmosphere than air since more effective YIG growthmore » during annealing process and lower FMR linewidth ({delta}H) of films could be achieved.« less
  • 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 electricalmore » 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}.« less
  • 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
  • Device quality hydrogenated amorphous silicon (a-Si:H) films have been deposited under a wide range of deposition conditions using dc magnetron reactive sputtering. The total hydrogen content (C/sub H/) has been varied from 0 to /similar to/40 at. % by changing the substrate temperature (T/sub s/) or hydrogen partial pressure (P/sub =/) independent of other deposition parameters. The films that contain C/sub H/ between 10 and 28 at. % have the highest quality. The optical band gap (E/sub g/) varies linearly with C/sub H/ for all deposition conditions studied. With increasing C/sub H/ the dark conductivity at 300 K decreases frommore » /similar to/1 x 10/sup -4/ to /similar to/1 x 10/sup -12/ (..cap omega.. cm)/sup -1/; however, the photoconductivity under AM-1 illumination, for the highest quality films, remains in the 0.8--3.5 x 10/sup -5/ (..cap omega.. cm)/sup -1/ range. The dark conductivity activation energy (E/sub a/) was measured to determine the Fermi-level (E/sub f/) position with respect to the conduction band (E/sub c/) and a linear correlation between E/sub g/ and E/sub a/ is found for high-quality films. The films having low hydrogen content (10« less
  • Amorphous CoZrNb films have been deposited by magnetron sputtering which can greatly improve the utilization efficiency of a magnetic alloy target with high permeability. The saturation magnetization 4{pi}{ital M}{sub {ital s}} of the CoZrNb films was about 14 kG. The easy and hard axes of magnetization of the films were orthogonal to each other in the film plane. The coercivity {ital H}{sub {ital c}} in the easy and hard directions decreased from 0.9 to 0.2 Oe after annealing in a rotating dc magnetic field {ital H}{sub {ital A}}. However, {ital H}{sub {ital c}} increased drastically to 20 Oe by heatingmore » at the annealing temperature {ital T}{sub {ital A}} of 400 {degree}C. With increasing {ital T}{sub {ital A}} and {ital H}{sub {ital A}}, the anisotropy field {ital H}{sub {ital k}} gradually decreased from 12 to 1 Oe and the resistivity {rho} also decreased from 200 to 150 {mu}{Omega} cm. Consequently, it was found that {ital H}{sub {ital c}} and {rho} depended strongly on {ital T}{sub {ital A}}; and that {ital H}{sub {ital k}} had definite relationships with both {ital T}{sub {ital A}} and {ital H}{sub {ital A}}.« less