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This article presents a novel approach for evaluating laser scribing quality through cross-section profiles generated from a three-dimensional optical profiler. Existing methods for assessing scribing quality only consider the width and depth of a scribe profile. The proposed method uses a cubic spline model for cross-section profiles. Two quality characteristics are proposed to assess scribing accuracy and consistency. Accuracy is measured by the ratio of the actual laser-scribed area to the target area (RA), which reflects the deviation from the desired profile. The mean square error (MSE) is a measure of how close each scribed cross-section under the same scribing conditions is to the fitted cubic spline model. Over 1370 cross-section profiles were generated under 171 scribing conditions. Two response surface polynomial models for RA and MSE were built with 18 scribing conditions with acceptable scribing depth and RA values. Both RA and MSE were considered simultaneously via contour plots. A scatter plot of RA and MSE was then used for Pareto optimization. It was found that the cross-sectional profile of a laser scribe could be accurately represented by a cubic spline model. A multivariate nonlinear regression model for RA and MSE identified pulse energy and repetition rate as the two dominant laser parameters. A Pareto optimization analysis further established a Pareto front, where the best compromised solution could be found. 

The nature of structural changes of nanosecond laser modification inside silicon is investigated. Raman spectroscopy and transmission electron microscopy measurements of cross sections of the modified channels reveal highly localized crystal deformation. Raman spectroscopy measurements prove the existence of amorphous silicon inside nanosecond laser induced modifications, and the percentage of amorphous silicon is calculated based on the Raman spectrum. For the first time, the high-resolution transmission electron microscopy images directly show the appearance of amorphous silicon inside nanosecond laser induced modifications, which corroborates the indirect measurements from Raman spectroscopy. The laser modified channel consists of a small amount of amorphous silicon embedded in a disturbed crystal structure accompanied by strain. This finding may explain the origin of the positive refractive index change associated with the written channels that may serve as optical waveguides. 

The development of thin-film photovoltaics has emerged as a promising solution to the global energy crisis within the field of solar cell technology. However, transitioning from laboratory scale to large-area solar cells requires precise and high-quality scribes to achieve the required voltage and reduce ohmic losses. Laser scribing has shown great potential in preserving efficiency by minimizing the drop in geometrical fill factor, resistive losses, and shunt formation. However, due to the laser induced photothermal effects, various defects can initiate and impact the quality of scribed grooves and weaken the module’s efficiency. In this regard, much research has been conducted to analyze the geometrical fill factor, surface integrity, and electrical performance of the laser scribes to reach higher power conversion efficiencies. This comprehensive review of laser scribing of photovoltaic solar thin films pivots on scribe quality and analyzes the critical factors and challenges affecting the efficiency and reliability of the scribing process. This review also covers the latest developments in using laser systems, parameters, and techniques for patterning various types of solar thin films to identify the optimized laser ablation condition. Furthermore, potential research directions for future investigations at improving the quality and performance of thin film laser scribing are suggested.