Properties of ultrafast laser textured silicon for photovoltaics

• Published in: Solar energy materials and solar cells 2011-10, Vol.95 (10), p.2745-2751
• Main Authors: Iyengar, Vikram V., Nayak, Barada K., More, Karren L., Meyer, Harry M., Biegalski, Michael D., Li, Jian V., Gupta, Mool C.
• Format: Article
• Language: English
• Subjects: ANNEALING; Applied sciences; Chemical etching; Crystal defects; CRYSTAL STRUCTURE; DEEP LEVEL TRANSIENT SPECTROSCOPY; DEFECTS; Devices; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; ETCHING; Exact sciences and technology; LASERS; Light trapping; Natural energy; Photoelectric conversion; Photovoltaic cells; Photovoltaic conversion; PROCESSING; SILICON; SILICON SOLAR CELLS; Solar cells; Solar cells. Photoelectrochemical cells; SOLAR ENERGY; TRANSMISSION ELECTRON MICROSCOPY; Ultrafast laser processing; Ultrafast lasers; X-RAY PHOTOELECTRON SPECTROSCOPY; X-RAY SPECTROSCOPY
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2011.04.011

In this work, we report a detailed material study of ultrafast laser textured silicon surfaces to gain insight into the impact of ultrafast laser processing conditions on photovoltaic device properties. A comprehensive study of the ultrafast laser processed silicon is achieved by determination of crystal structure and elemental compositional changes using transmission electron microscopy, compositional mapping by energy dispersive X-ray spectroscopy and depth profiling compositional determination using X-ray photoelectron spectroscopy. We have observed material non-homogeneity, impurity incorporation and strained silicon, all limited to the surface. A combination of chemical etching and thermal annealing was used to remove the laser induced changes and the material was restored to its starting quality. Further, silicon solar cell devices on such defect-etched surfaces are fabricated. These devices are characterized through dark i– v analysis and Fourier transform deep level transient spectroscopy for defect analysis. [Display omitted] ► Ultrafast laser texturing of silicon surfaces. ► Laser induced self-organized micro-structures for light trapping. ► Material and electrical study of ultrafast laser textured silicon surfaces. ► Laser-affected regions removed by post-texturing treatments to restore original material quality. ► Need for optimized surface passivation schemes.