Browse Prior Art Database

Buried Heterostructure Produced without Growth Interruption

IP.com Disclosure Number: IPCOM000109071D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Tischler, M: AUTHOR

Abstract

Disclosed is a method for fabrication of a buried heterostructure by the technique of metal-organic vapor phase epitaxy without a growth interruption. Instead of successive deposition and etching steps which are typically used to produce buried heterostructure devices (such as lasers), this method utilizes the phenomenon of orientation-dependent ordering of the constituent elements in compound semiconductor crystals to produce adjacent areas of the same composition material, but with a different bandgap.

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Buried Heterostructure Produced without Growth Interruption

       Disclosed is a method for fabrication of a buried
heterostructure by the technique of metal-organic vapor phase epitaxy
without a growth interruption.  Instead of successive deposition and
etching steps which are typically used to produce buried
heterostructure devices (such as lasers), this method utilizes the
phenomenon of orientation-dependent ordering of the constituent
elements in compound semiconductor crystals to produce adjacent areas
of the same composition material, but with a different bandgap.

      The phenomenon of ordering is observed in many III-V alloys,
most notably InGaP and InGaAlP.  Ordering means that the placement of
the mixed-group elements, in this case group III, in the lattice has
some regularity as opposed to being randomly distributed.  The degree
of ordering is dependent on the particular alloy, as well as the
growth conditions, especially growth temperature.  Ordering affects
the band structure of the material, and, thus, the band gap also
changes with growth temperature.  Ordering is also dependent on the
orientation of the substrate.  Usually, these alloys show strong
ordering tendencies on (001) substrates, which decreases as the
orientation is tilted towards the <111> direction (1,2).  Some alloys
can exhibit quite large changes in bandgap, up to perhaps 150-200
meV.

      A buried heterostructure can be produced by making use of these
characteristics.  For example, if a (001) substrate is etched to
produce a trough with (111) sidewalls, an ordered alloy would be
deposited on the horizontal surfaces while an unordered alloy would
be deposited on the (111) faces.  The unordered alloy has a larger
bandgap and thus would form a lateral heterojunction.  I...