Edge Breakdown Suppression of Avalanche Photodiodes Using Zn Diffusion and Selective Area Growth

Avalanche photodiodes are fabricated and characterized using a single diffusion fabrication process with the surface patterned by selective area growth prior to diffusion. Raster mapping of the photocurrent near the breakdown voltage is used to characterize the electric field distribution in the multiplication layer. Devices fabricated with the precursor CBrCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> introduced during selective area epitaxy show a smoother surface morphology and effective edge breakdown suppression, while those fabricated without CBrCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> have a rougher surface morphology and exhibit evidence of premature edge breakdown at the corners of the device along specific crystal orientations. Comparison of the dark current-voltage curves below breakdown shows a reduction in dark current associated with the use of CBrCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , as well as with the inclusion of floating guard rings in the device design.

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