EE757:CRYSTALLINE SILICON SOLAR CELLS: THEORY AND PRACTICE
Theory: Brief review of semiconductor device physics - band structure - carrier concentrations - carrier generation and recombination - effective lifetime and surface recombination velocity - carrier transport - optical absorption and reflection.
Practice: (i) measurement of sheet resistance of a silicon wafer - determination of the type of wafer - estimation of the mobility and diffusion coefficient of the majority carriers (ii) measurement of carrier lifetime and surface recombination velocity (iii) measurement of reflectivity of a polished silicon surface.
Theory: p-n junction diodes - derivation of dark IV characteristics including surface recombination - illuminated IV characteristics - contacts - series resistance in solar cells - shunts in solar cells.
Practice: Simulation of dark and illuminated IV characteristics of pn junction diodes using PC1D - analysis of fermi levels, potential, electric field and carrier distributions, generation and recombination rates within the diode - simulation of illuminated characteristics using measured reflectance data - leakage currents - impact of various parameters like carrier lifetime, surface recombination, and semiconductor thickness on carrier distributions, recombination currents and dark and illuminated IV of the diode, impact of the above on solar cell performance parameters (Isc, Voc, FF, efficiency).
Theory: wet clean and etch processes - Diffusion in silicon - plasma etching - thin film growth and deposition (oxidation, PECVD, ALD, evaporation), screen printing process - laser processes for silicon solar cell fabrication
Practice: Texturization of silicon surface using KOH, measurement of reflectance, observation of the surface using optical microscope and assessment of pyramid size and distribution, review of device simulation using the measured reflectance data - Phosphorous diffusion using POCl3, design of diffusion process - experiment, sheet resistance measurements - edge isolation process using plasma etching
Jenny Nelson, The Physics of Solar Cells, Imperial College Press, 2007
D. K. Schroder, Semiconductor Material and Device Characterization, Wiley Interscience, 2006
C. S. Solanki, Solar Photovoltaics: Fundamentals, Technologies and Applications, Prentice Hall of India, 2009