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Improved Semiconductor Diodes

IP.com Disclosure Number: IPCOM000097683D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 17K

Publishing Venue

IBM

Related People

Anderson, RL: AUTHOR

Abstract

Improved diodes are made by controlling the variation of the transition capacity of the junction by control of the net charge concentration with distance from the junction.

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Improved Semiconductor Diodes

Improved diodes are made by controlling the variation of the transition capacity of the junction by control of the net charge concentration with distance from the junction.

In a graded junction where the doping of donors increases with distance X from the junction N(D)-N(A), concentration of donors minus acceptors is proportional to X/n/. Where n is positive, the capacity is expressed as ***

(Image Omitted)

***

The reverse voltage V is negative and V(D) is the diffusion voltage.

For large N the capacity is independent of voltage. Where the value N(D)- N(A) decreases as X increases, the capacity varies rapidly with voltage.

These diodes are fabricated with gallium arsenide semiconductor material. Arsenic has a higher vapor pressure than gallium. When a gallium arsenide body is exposed to heat, the arsenic vaporizes. The surface of the gallium arsenide has an excess of gallium and is more P type than the bulk. Similar results are obtained by chemically treating the GaAs to remove arsenic and then heating the material so that diffusion and re-adjustment in atom position occurs. A region of rapidly varying N(D)-N(A) is produced which yields a rapid rate of change in capacitance. This is when the edge of the transition region is in the portion of the body with the varying N(D)-N(A). When the GaAs is N type, the variation of capacity with voltage is low. Where the GaAs is P type there is a large variation of capacity with voltage.

This cap...