Optical Transmission Enhancement of Fluorine Doped Tin Oxide (FTO) on Glass for Thin Film Photovoltaic Applications

Transparent conductive oxide layers (TCO) are used as electrodes for thin film applications. The optical performance of TCOs can be improved by implementing textured surfaces that will increase the overall transmission of light through the TCO layer. In this paper, a model is developed using Synopsys TCAD to accurately predict the behavior of a thin film of fluorine doped tin oxide (FTO) on a glass substrate. Its accuracy is assessed using experimental data and was further validated by using the simulated transmission curve to estimate the thickness. It is then used to assess the effect of two types of texturization patterns: rectangular and pyramidal. Inductively coupled plasma- reactive ion etching (ICP-RIE) was used to implement rectangular type patterns on FTO samples. The results show that the rectangular patterns result in minor total transmission gains of 1 – 2 percentage points. This is due to a reduced absorption caused by the removal of material. The best pyramidal patterns increased total transmission by over 5 percentage points. These increases are attributed to reduced reflection.