Zn1-xMgxO thin films deposited by original Infrared assisted Spray Chemical Vapor Deposition: evaluation of structural, optical and electrical properties with the aim of provide Cu(In,Ga)Se2 based photovoltaic devices

Abstract

In this work, magnesium doped zinc oxide (Zn1-xMgxO) thin films were deposited using an original infrared assisted Spray Chemical Vapor Deposition (Spray-CVD) technique on borosilicate glass substrates. With a simple, safe and cost-effective apparatus, Zn1-xMgxO thin films was studied in a range of 0 to 40% in precursor mass ratio r = [Mg]/([Zn]+[Mg]). The optimal deposition temperature was 500°C. X-ray diffraction analysis confirmed the presence of magnesium in the hexagonal Wurtzite crystal lattice of zinc oxide for r values lower than 30%. The optical properties have been investigated by spectrophotometry and showed that the transparency is higher than 80% in the visible and infrared spectral domain for r values lower than 20%. The band gap energy increased from 3.28 to 3.94 eV (0 < r < 40%), and the resistivity of the samples increased from 4.16.10-2 to 7.09.10+3 Ω.cm (Hall effect measurement). Additional characterizations have been realized by X-ray fluorescence (XRF) and energy dispersive X-ray spectrometry (EDX). All results demonstrate that Zn1-xMgxO thin films with r = 20% obtained by our Spray-CVD method is an interesting candidate for buffer layer application in Cu(In,Ga)Se2 based solar cells.