Non-polar a-plane oriented ZnO:Al thin films for optoelectronic applications

Highlights: • Growth of non-polar a-plane oriented aluminium doped ZnO (AZO) thin films by the pulsed laser ablation technique. • A remarkable switching behaviour from p-type to n-type semi conductivity in films grown at laser ablation fluence 35 J/cm². • Thin film prepared at laser ablation fluence 35 J/cm² has better figure of merit values compared to other reported works. • AZO film prepared at 35 J/cm² fluence have the required optoelectronic characteristics suitable for LED applications. This paper reports the details of fabrication of aluminum-doped zinc oxide (AZO) thin films on Corning glass substrates by pulsed laser deposition technique at different laser ablation fluences: 8.75, 17.5 and 35 J/cm². The influence of laser fluence on the structural, optical and electrical properties of the prepared thin films is analyzed and discussed. X-ray diffraction pattern of AZO thin film confirmed a non-polar a-plane oriented crystal growth in the AZO film prepared at higher fluences. Field emission scanning electron microscopic images indicate the dependence of grain size of AZO on the laser fluence. The highest transmittance (>86%) and the lowest resistivity is attained in thin film prepared at 35 J/cm² fluence. A remarkable switching behavior from p-type to n-type semiconductivity is observed. The achieved optoelectronic properties of non-polar a–plane oriented AZO thin film, suggests the prepared thin film is a promising material in the fabrication of LED device.