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Reducing Detrimental Minority Carrier Effects in Semiconductor Devices

IP.com Disclosure Number: IPCOM000078586D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Young, DR: AUTHOR

Abstract

Minority carriers generated in a semiconductor can diffuse to the depletion regions of semiconductor devices, where they are transported by the electric field. This leads to an undesirable current in the device. It is proposed to use another depletion region in the vicinity to carry away the minority carriers into a noncritical region, and hence reduce the magnitude of the undesired current.

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Reducing Detrimental Minority Carrier Effects in Semiconductor Devices

Minority carriers generated in a semiconductor can diffuse to the depletion regions of semiconductor devices, where they are transported by the electric field. This leads to an undesirable current in the device. It is proposed to use another depletion region in the vicinity to carry away the minority carriers into a noncritical region, and hence reduce the magnitude of the undesired current.

The principle of operation is illustrated by the figures. Fig. 1 shows a depletion region of a semiconductor, with minority carriers generated in the bulk of the semiconductor and diffusing into the depletion region, where they are transported by the field present. These carriers can diffuse from a considerable distance away. This distance is called the diffusion length for minority carrier diffusion L. This leads to a relatively large volume for minority carrier generation.

Fig. 2 shows the principle hereof. In this case, a second depletion region is used to reduce the volume available for minority carrier generation, to the volume corresponding to a depth of D/2. Minority carriers generated in the top depletion region itself will not be reduced. However, in a device, the width of the depletion region is considerably less than the diffusion lengths, so this effect will be relatively small.

In Fig. 3 a charge-storage area of a charge-coupled device is illustrated, wherein the depletion region is generated...