In a p-n junction solar cell, the ratio of the thickness of the p-Si wafer to the thickness of the n-Si layer is approximately .

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(2) 1000. Given: a p-n junction solar cell is made from a p-Si wafer about 300 μm thick, on whose illuminated face a thin n-Si layer about 0.3 μm thick is grown by diffusion. Idea: the top layer is made very thin on purpose, so that photons are not absorbed before they reach the depletion region where the built-in field can separate the electron-hole pairs they create. Ratio = (300 μm)/(0.3 μm) Ratio = 1000, so the wafer is about a thousand times thicker than the n layer.

In a p-n junction solar cell, the ratio of the thickness of the p-Si wafer to the thickness of the n-Si layer is approximately ________.

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