UV Laser Selective Ablation of Photovoltaic Materials for Monolithic Interconnection of Devices Based on a-Si:H

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2438-2442
In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of Diode-Pumped Solid-State Laser Sources (DPSS). We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. Additionally we present preliminary results for Heat affected zone estimation using refractive index measurements. We include a comparison of ablation thresholds for different materials of interest as well. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si;H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial lasers sources as an alternative to standard backscribing process in device fabrication.