Browse Prior Art Database

Improved Normal-Emission Reflector for Stripe Lasers Using Sublime Technology

IP.com Disclosure Number: IPCOM000100519D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 100K

Publishing Venue

IBM

Related People

Brodsky, MH: AUTHOR [+4]

Abstract

Disclosed is a method of manufacture of injection lasers where the laser emission is normal to the wafer surface.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Improved Normal-Emission Reflector for Stripe Lasers Using Sublime Technology

       Disclosed is a method of manufacture of injection lasers
where the laser emission is normal to the wafer surface.

      The most favorable geometry for injection lasers is that of a
stripe, where the active region is "long" and "thin".  Since the
stripe is generally made parallel to the surface of the wafer,
emission from such lasers from the "polished" face at one (or both)
ends of the stripe is parallel to the surface of the chip.  If this
emission occurred normal to the chip surface, the lasers could be
positioned arbitrarily on the substrate in an array of emitters,
rather than just a single linear array.

      A recent application of anisotropic Reactive Ion Etching (RIE)
at 45 degrees to the surface has been used to produce facets that
result in the laser emission directed normal to the chip surface.
Unfortunately, the resulting facet is very rough, reflecting both the
edge roughness of the RIE mask and the inherent roughness of the RIE
process itself.  Mass transport at elevated temperatures has been
used to smooth the facet somewhat, but results are still far from
ideal.

      SUBLIME technology (*) introduces a new tool to the arsenal of
solid-state laser designers.  It is now possible to make accurate
flats at angles 45 and 90 degrees to one another by anisotropic
thermal etching.  Previously, with silicon and gallium arsenide
technology, anisotropic etching was limited to stopping on <111>
planes, and now the etch stops on <110> planes in certain cases.

      The preferred embodiment of this invention involves combining
two different etching techniques, namely RIE and SUBLIME (anisotropic
thermal etching).  RIE is used to produce the vertical emitting facet
of the traditional stripe laser, while SUBLIME is used to form a
polished, 45-degree reflector for directing the laser emission upward
from the surface.  In addition, SUBLIME is used for producing the
cavity within which the stripe laser itself is grown.

      The process is as follows: first, an und...