Browse Prior Art Database

Electroluminescent Device Based on Silicon Semiconductor

IP.com Disclosure Number: IPCOM000104139D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Collins, R: AUTHOR [+2]

Abstract

This disclosure describes a method for making an electroluminescent device based in silicon. Silicon normally does not emit light efficiently because it is an indirect gap semiconductor. In this disclosure, porous silicon, which does emit light efficiently, is used in the active region of the device. Such devices are easily integrated with conventional silcon-based electronic circuits

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Electroluminescent Device Based on Silicon Semiconductor

      This disclosure describes a method for making an
electroluminescent device based in silicon.  Silicon normally does
not emit light efficiently because it is an indirect gap
semiconductor.  In this disclosure, porous silicon, which does emit
light efficiently, is used in the active region of the device.  Such
devices are easily integrated with conventional silcon-based
electronic circuits

      Fabrication of this device begins with a structure consisting
of an n-type layer on top of a p-type layer.  The top n-type layer is
masked to form the top contact of the device, and the unmasked
portion of the top n-type layer is removed.  The sample is then
electrochemically etched under conditions of positive bias on the
p-type layer, so that the p-type material becomes  porous.  It will
become porous laterally as well as vertically, and eventually one
will have an n-type silicon island on top of a porous silicon layer.
The electroluminescent device is then contacted from the top n-type
layer and the bottom p-type layer.  The physical contacts could be on
the top and bottom of the wafer or both from the top.  Forward
biasing this junction causes carriers to be injected into the porous
region, where they will recombine and emit light.  It may be
advantageous to passivate the sides of the device; this could be done
by depositing a dielectric film or by oxidizing the structure.

      An alternate structure could be made where the starting
substrate is silicon on an insulating substrate, for example
sapphire.  An n-type region, which will be one contact to the devi...