Effects of laser pulse energy on the structural, optical and electrical properties of pulsed laser deposited Ga-doped ZnO thin films

Abstract

Transparent conducting Ga-doped ZnO (GZO) thin films were deposited on glass substrate by pulsed laser deposition (PLD). The effects of laser pulse energy ranging from 80 to 200 mJ on microstructural, surface morphology, electrical and optical properties of GZO films were investigated in detail. XRD patterns have shown that all samples were hexagonal wurtzite structure presenting predominant orientation along the (002) c-axis direction, and the film obtained at 160 mJ showed the optimal crystallinity. The Raman spectra demonstrate that GZO films have oxygen vacancies, Zinc interstitials, and residual stress. The compact, homogenous and flat surface morphology of GZO films were observed by AFM. Hall effect measurements revealed that the electrical properties of samples were dominated largely by the crystallinity and the minimum resistivity of 6.10 × 10−4 Ω cm was obtained when GZO film grown at 160 mJ. Optical transmission spectra displayed an average transmittance higher than 90.6% for all GZO samples in the visible range. The film deposited at 160 mJ exhibited the maximum figure of merit of 22.70 × 10−3 Ω−1, owing to the low resistivity and high transmittance.