Browse Prior Art Database

Junctions with Varying Band Gap

IP.com Disclosure Number: IPCOM000092120D
Original Publication Date: 1968-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Marinace, JC: AUTHOR

Abstract

In this electroluminescent diode structure, the energy band-gap along the junction is nonuniform. In A, layer 1 of N-type Al:GaAs is epitaxially grown on semi-insulating GaAs substrate 3. The Al concentration is highest at interface 5 and gradually reduces to a minimum at surface 7. Using conventional masking techniques, Zn is diffused into a portion of surface 7 to form PN junction 9 having curved portions 11 which extend to surface 7. Thus, portions 11 of junction 9 exhibit varying, or nonuniform, energy band-gaps because of the receding Al concentration in layer 1. When junction 9 is forward biased, radiation is emitted in a continuous band of frequencies corresponding to the energy band-gap limits along junction 9. In B, an alternate diode structure has a planar PN junction.

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Junctions with Varying Band Gap

In this electroluminescent diode structure, the energy band-gap along the junction is nonuniform. In A, layer 1 of N-type Al:GaAs is epitaxially grown on semi-insulating GaAs substrate 3.

The Al concentration is highest at interface 5 and gradually reduces to a minimum at surface 7. Using conventional masking techniques, Zn is diffused into a portion of surface 7 to form PN junction 9 having curved portions 11 which extend to surface 7. Thus, portions 11 of junction 9 exhibit varying, or nonuniform, energy band-gaps because of the receding Al concentration in layer 1. When junction 9 is forward biased, radiation is emitted in a continuous band of frequencies corresponding to the energy band-gap limits along junction 9. In B, an alternate diode structure has a planar PN junction. Substrate 3 and layer 1 of A are cleaved to provide a planar surface 13 over which layer 15 of P-type GaAs is epitaxially grown. Alternatively, layer 15 can be formed by diffusion techniques.

Since the Al concentration layer 1 reduces in the direction of the arrow, the energy band-gap of PN junction 17 is nonuniform and emits polychromatic light when forward biased. If desired, substrate 3 can be mechanically lapped, to a depth indicated by the dashed line. The structures of A and B can be utilized as broad-band light detectors.

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