Role of substrate and annealing on microstructural, optoelectronic and luminescence properties of RF magnetron sputtered AZO thin films in confocal configuration

In this investigation, RF magnetron sputtering technique in confocal configuration was used to fabricate AZO thin films with a deposition time of 1 h 30 min on glass, and quartz substrates. The effects of substrate and air annealing at 400 degrees C for 60 min on the structural, morphology and surface topography, optical, electrical and luminescence properties are studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, Ultraviolet-Visible-Near Infrared spectrophotometry, Hall Effect measurements and photoluminescence spectroscopy. X-ray diffraction patterns show that all AZO films are polycristalline and have a hexagonal wurtzite structure with a preferential orientation along the (002) plane. The crystallinity, (002) peak intensity, grain size and surface roughness of the films are found to be dependent on substrate and annealing. According to Ultraviolet-visible measurements, as-deposited and annealed AZO thin films grown on glass substrates demonstrate a better average transparency in the visible region. Moreover, for both substrates, the annealing in air causes an enhancement in the optical transmittance and a reduction in the band gap of AZO films. Hall Effect measurements confirm the n-type conductivity of AZO films and their electrical properties are substrate dependent and highly affected by air-annealing. In fact, as the temperature increases from RT to 400 degrees C, the electrical resistivity of films on glass and quartz substrates increases strongly by approximately 80 times from 1.25 x 10(-3) and 1.05 x 10(-3) Omega cm to 9.09 x 10(-2) and 8.82 x 10(-2) Omega cm, respectively. Room temperature photoluminescence investigations put into evidence that emission spectra are depending on the substrate nature and annealing. In particular an intense violet emission is observed for the AZO film deposited on quartz substrate at room temperature. The annealing at 400 degrees C leads to the enhancement of the UV emission, the quenching of the violet emission and the improvement of the green and yellow-red bands.

Automated summary

In this study, AZO thin films were fabricated on glass and quartz substrates using RF magnetron sputtering technique in confocal configuration. The effects of substrate and air annealing on the properties of the films were investigated. The results showed that the properties of the films, including crystallinity, surface roughness, optical transmittance, and electrical conductivity, were influenced by substrate type and annealing temperature.