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Title:	Evaluation of oxide passivated low reflection nano-structured solar cells
Authors:	Cheow Siu Leong (P47066)
Supervisor:	Kamaruzzaman Sopian, Prof. Dato' Dr.
Keywords:	Solar cells Silicon solar cell Nanostructured materials Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	16-Jul-2013
Description:	The main processes in conventional silicon solar cell manufacturing are surface cleaning, saw damage removal, and texturing. These steps require excessive water and chemical usage. In addition 10 % of the wafers are wasted through etching. These steps are followed by surface passivation and reflection reduction through expensive and inflammable, toxic-gas based plasma enhanced chemical vapor deposition process for deposition of high index anti-reflection SiN films. The main objective in this work was to investigate simplify and environmental friendly approach for industrial silicon solar cell manufacturing. In this new process, room temperature chemical texturing method has been investigated aimed for removal of saw damage and formation of randomly-textured nanoscale surfaces. Surface reflection measurements from these surfaces have been carried out was comparable or 1% lower than SiN-coated surfaces. Eliminating the need for deposition of high index SiN films. Si nanostructure passivation has been achieved with an oxide film grown as part of the POCl3 emitter process. Solar cells fabricated with these methods have exhibited high efficiencies at approximately 15%. These innovations have significantly reduced water and chemical usage, and have also eliminated expensive, silane-based plasma processing without restructuring the existing industrial fabrication process. The experimental work on diffusion was carried out in a quartz tube furnace using liquid source phosphoryl trichloride (POCl3) as the doping source. Process temperatures in the range 875°C - 900°C with drive-in time of 15 minutes were investigated. The silicon wafers were 12.5x12.5 cm2, p-type crystalline (mono and poly) with ~ 200-250 μm thickness and approximately 1 - 10 ohm-cm resistivity. These diffusion processes produced an emitter with a sheet resistance in the range of 10 ohm/square to 40 ohm/square. Thermally-grown oxide films as part of the diffusion process for passivated textured surfaces has been investigated. Simulation studies conducted using PC1D5 demonstrated good agreement with experimental results. Hence, indicating excellent surface passivation of in-situ oxide films. The highest efficiency obtained to date in this research is 15% for mono-crystalline single junction silicon solar cell with 200 μm thickness. Inability to achieve higher efficiency was limited by the minority carrier lifetime of the wafers. Open-circuit voltage, short circuit current density, and fill factor of the cell fabricated with the optimised process were 610 mV, 35.83 mA/cm2 and 69%, respectively.,Certification of Master's/Doctoral Thesis" is not available
Pages:	121
Call Number:	TA418.9.N35C495 2013 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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