This paper presents the design and test of a photodiode with improved conversion efficiency for on-chip solar energy harvesting applications. The improved efficiency is achieved by exploiting the lateral photo response of the photodiode through the usage of diodes with fractal geometries. The fractal diodes have a large perimeter-to-area ratio which translates into more collected charges due to lateral photo response. An approximation of the quadric Koch island fractal has been designed and fabricated in a 0. 5?m CMOS process along with a rectangular photodiode of equal area but different perimeter that serves as the control. Measurements of the fabricated chip show improvements in the charge collection of the fractal-based photodiode of up to 6% with respect to the rectangular control photodiode.

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Fractal Photodiode