From Photonics and Lasers
 

Schottky Photodiode

The PIN and avalanche photodiodes discussed in the previous two sections are both p-n-junction-based devices. In contrast, the Schottky photodiode utilizes a metal-semiconductor junction to separate and collect the photogenerated charge carriers. Fig. 14-16 illustrates the operation of a Schottky photodiode for the metal-n-n+ configuration, the most common type. Photons pass through a partially transparent metallic layer (often gold), and are absorbed in the n-type semiconductor. Charge carriers generated within the depletion region are efficiently swept out by the built-in electric field (see Fig. 10-17), giving rise to a photocurrent i . Just as for a PIN photodiode, the diffusion tail in the time response can be minimized by adjusting the donor concentration NDin the n-type region so that the depletion region extends all the way through to the n+ layer. Apart from the lack of a p-type layer, the structure and operation of a Schottky photodiode is similar to that of a PIN photodiode.

Schottky photodiodes have some advantages over PIN photodiodes for certain applications. One advantage is a practical issue in manufacturing the devices. In connecting the Schottky photodiode with wires in the external circuit, only one metal-semiconductor connection needs to...


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© 2006 John Wiley & Sons, Inc.

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Topics of Interest

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