High-quality radio frequency–sputtered ZnO were grown on Si substrates at 400 °C at various partial gas pressures (Ar/Ar+O2). Subsequently, to remove as-grown defects, high temperature annealing from 700 to 900 °C on as-grown samples in constant oxygen flow for 10 s was performed. X-ray diffraction study confirmed the formation of highly crystalline films with a dominant peak at (002). The sample grown in 50% Ar and 50% O2 ambient exhibited the lowest linewidth (2θ=~0.2728°) and highest stoichiometry. Grain size of the as grown samples decreased with increase in the partial pressure of oxygen till a certain ratio (1:1), and photoluminescence (PL) improved with increase in annealing temperature. Low-temperature (18 K) PL measurements showed a near-band-edge emission peak at 3.37 eV, and the highest peak intensity (more than six orders compared to others with narrow linewidth of ~0.01272 eV) was exhibited by the sample annealed at 900 °C and was six orders higher than that of the as-grown sample. All as-grown samples exhibited dominant visible-range peaks due to emission from defect states.
Bibliographical noteFunding Information:
The authors acknowledge the financial support from the Department of Science and Technology, India, and the partial financial support from the Department of Information Technology and the Nanofabrication facility at Indian Institute of Technology Bombay (IITB). The authors also acknowledge the SPM Physics and Hall Measurement Physics department at IITB. The funders had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.
© 2017 Elsevier Ltd
- RF sputtering