Preparation method of double-textured ZnO:B films deposited by MOCVD on plasma etched polymer buffer

Abstract

With the aim of enhancing light trapping phenomenon in PV thin film silicon devices, a method has been developed to produce highly textured TCO surfaces by the growth of ZnO:B on a buffer layer consisting of UV-cured highly transparent acrylic polymer (IBA) whose surface had been modified by RIE process. Different RIE etching conditions, particularly RF-power and process duration, have been used to obtain different polymer surface modifications. The effect of different treatment conditions on polymer surface has been systematically investigated and subsequently correlated to the properties of ZnO:B films deposited by MOCVD on these modified polymer surfaces.The surface morphology of zinc oxide film, growth on IBA buffer layer, changed from conventional pyramid-like single-texture to cauliflower-like double-texture. The morphology of double-textured ZnO strongly depended on the surface properties of the etched polymer. Excellent scattering properties were obtained and at the wavelength of 800nm the haze value increased from 7.5% (pyramidal-like single-texture ZnO layer on glass) to 68% (double textured ZnO film obtained on etched IBA, treated for 20min at RF-power of 80W). The RMS roughness showed similar behaviour: it increased at the increasing of the etching time and the highest value of 160nm was obtained for cauliflower-like ZnO:B film. Good electrical properties were maintained for double-textured ZnO:B films with excellent scattering properties.