Structural, optical and electrical evolution of Al and Ga co-doped ZnO/SiO2/glass thin film: Role of laser power density

• Main Authors: Samavati, A., Samavati, Z., Ismail, A. F., Othman, M. H. D., Rahman, M. A., Zulhairun, A. K., Amiri, I. S.
• Format: Article
• Language: English
• Published: Royal Society of Chemistry 2017
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utm.my/id/eprint/75737/1/AlirezaSamavati_StructuralOpticalandElectricalEvolutionofAl.pdf; http://eprints.utm.my/id/eprint/75737/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025614838&doi=10.1039%2fc7ra04963c&partnerID=40&md5=f49dec9f8a9935631a0b9479f0afd9b4

This study investigates the characteristics of laser annealed thin films of Al-Ga co-doped zinc oxide (ZnO:Al-Ga) nanoparticles on top of SiO2/glass. The samples are synthesized using simple sol-gel, spin coating and radio frequency magnetron sputtering methods. The studies on the structural, optical and electrical properties of the pre-annealed sample and samples annealed at different power densities are conducted using a variety of characterization techniques. The samples exhibit a hexagonal wurtzite structure. Spectroscopic and nano-imaging techniques confirm that by increasing the laser power density, the crystallinity of the samples is improved and the nanoparticle size is enhanced from ∼10 nm to ∼35 nm. Spectroellipsometry is employed to calculate the refractive index, extinction coefficient, and real and imaginary components of the dielectric constant. The resistivity exhibits a minimum value at 440 mJ cm-2. Results demonstrate that the optical band gaps of the samples are between 3.29 and 3.41 eV, which are greater than that of pure bulk ZnO (band-gap of 3.21 eV). Several vibrational modes occur as a result of the dopant combination in the ZnO lattice. A discussion on the origins of modes and their intensity changes is provided. This work suggests that a laser annealing process can be an effective tool to fabricate various thin films with enhanced crystallinity. The optical and electrical properties can also be adjusted by varying the power density.