Date of Award
Master of Science in Electrical Engineering - (M.S.)
Electrical and Computer Engineering
N. M. Ravindra
In order to achieve maximum light collection efficiency in silicon made solar cells, reflectivity of the silicon surface must be reduced to as low level as possible. In the past, researchers have concentrated on coating the Si surfaces with anti-reflection coatings. Another approach was to form textures on the Si wafers to capture further the light impinging on the solar cells.
Theoretical studies, which were based on ray tracing approach, revealed that some geometrical patterns are better capturing the light than others. In this work, different geometrical surface configurations on a Cu/n-Si Schottky-barrier solar cell have been investigated. The configurations which were considered were V-shaped, M-shaped, asymmetric V-shaped, and asymmetric M-shaped structures. They showed improvement in the short-circuit current over a flat surface solar cells, while the open-circuit voltage remains practically unchanged. Namely, the improvement achieved was not on the expense of the crystallographic structure of the Si surface.
The geometrical surface configurations in a silicon wafer were fabricated by an ultraviolet excimer laser ablation in air, HF, or KOH for similar incident laser power densities and pulse durations. For laser ablation in air, the Si sample was subsequently processed by annealling and localized etching. The Schottky-barrier solar cell made by laser ablation in air shows slight improvement in light collection efficiency compared to flat surface solar cell. A significant improvement was observed when laser ablation in solutions technique was used.
Fang, Kejia, "Improvement of light collection efficiency by laser-induced patterning the surface of schottky-barrier solar cells" (1992). Theses. 2252.