Simultaneous enhancement of electrical conductivity, uniformity, and near-infrared transmittance via laser annealing on ZnO:Ga films deposited by atmospheric pressure plasma jet

Atmospheric pressure plasma jet (APPJ) has been used to deposit transparent conductive oxides (TCO) in ambient conditions with optoelectronic properties comparable to vacuum-based techniques. However, APPJ-deposited TCO films tend to exhibit a relatively low electrical uniformity, and it is still challenging to improve TCO's conductivity without compromising the near-infrared (NIR) transmittance. Here, we demonstrate that continuous CO2 laser annealing can simultaneously enhance the electrical conductivity, uniformity, and NIR transmittance of Ga-doped zinc oxides (GZO) prepared by APPJ on 5 x 5 cm(2) glasses. GZO films annealed with a laser power of 4.35 W achieve a low resistivity (5.5 x 10(-4) Omega cm - 6.0 x 10(-4) Omega cm), a high Hall mobility (14.5 cm(2) V-1 s(-1) - 15.5 cm(2) V-1 s(-1)), a low non-uniformity in resistivity (3% - 5%) and a high transmittance in the visible spectra (>80%, including 10% loss due to the glass substrate). The transmittance in the NIR spectra increases from 52.6% to 61.4% (+16%), and may be further improved by reducing the carrier concentration (6.8 x 10(21) cm(-3) - 7.6 x 10(21) cm(-3) in this study). The enhancement may be attributed to the reduction of Ga-O clusters, which act as barrier traps that degrade the carrier mobility. Our findings may also be applied to other scanning-based deposition methods such as spray pyrolysis. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, continuous CO2 laser annealing was shown to enhance the electrical conductivity, uniformity, and NIR transmittance of GZO films deposited by APPJ. The improvement may be attributed to the reduction of Ga-O clusters which act as barrier traps in degrading carrier mobility.