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Surface Charge Guides Using Heavily Doped Regions

IP.com Disclosure Number: IPCOM000077294D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

DiStefano, TH: AUTHOR

Abstract

In the operation of a charge-coupled device, a charge depletion region is created in a semiconductor surface below the area of a charged electrode. The depleted area can be moved along the surface by sequentially charging a series of electrodes. Any minority carriers placed in the inverted region will spread to fill the potential well in the inverted area and will follow the movement of that area. Since the width of the charge domain is the same as that of the supporting electrode, one chain of electrodes will support only one column of surface charge domains. The following are described for a charge-coupled device:

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Surface Charge Guides Using Heavily Doped Regions

In the operation of a charge-coupled device, a charge depletion region is created in a semiconductor surface below the area of a charged electrode. The depleted area can be moved along the surface by sequentially charging a series of electrodes. Any minority carriers placed in the inverted region will spread to fill the potential well in the inverted area and will follow the movement of that area. Since the width of the charge domain is the same as that of the supporting electrode, one chain of electrodes will support only one column of surface charge domains. The following are described for a charge-coupled device:

(1) The use of regions of high-majority doping to form barriers to the propagation of minority surface charge.

(2) The use of diffused regions to divide a single column of surface-charge domains into several parallel, independent columns under the same set of sequentially activated electrodes.

Charge domains in a charge-coupled device expand to fill the area under a sustaining electrode. Heavily doped regions in the substrate constrain the charge domain. Thus, one electrode can support several domains.

By using heavily doped regions in the substrate, the depleted region and the charge domain can be shaped to any arbitrary size. In particular, the depleted region can be cut into many segments as is shown in Figs. 1 and 2. The electric field at the semiconductor surface is insufficient to invert the heav...