Browse Prior Art Database

Improved Ridge Guide Laser

IP.com Disclosure Number: IPCOM000108920D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Benedict, M: AUTHOR [+3]

Abstract

The optical modes of ridge-guide lasers are very sensitive to the geometry of the ridge and the current density at the base of the ridge. If the ridge is shaped with negatively sloped sidewalls, as described in this article, several advantages result.

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Improved Ridge Guide Laser

       The optical modes of ridge-guide lasers are very
sensitive to the geometry of the ridge and the current density at the
base of the ridge.  If the ridge is shaped with negatively sloped
sidewalls, as described in this article, several advantages result.

      It has been shown that chlorine gas at room temperature
anisotropically etches AlGaAs along the 110 plane.  Referring to the
figure, this property can be used to produce a ridge 1, which is 57o
off vertical.  When an etch depth of 1.55 microns is used, the
undercut on each side will be 1 micron.  Therefore, with a 3.5 micron
ridge top 2 and photoresist feature size, the dimension at the ridge
bottom 3 is 1.5 microns.  Once the ridge 1 has been formed, an
imbedding layer 4 is deposited, followed by opening a contact region
5 on top of the ridge 1, prior to metallization 6.

      The figure is a schematic view of an embodiment and does not
represent an optimized design.  If compared with the commonly used
process which produces positive sidewall slopes, this new process
results in negative slopes and has several advantages:
1.   The new process is a dry chemical etch; external monitors can
therefore be used to control the etch depth.
2.   Since the sidewall slope is primarily determined by crystal
orientation and etch temperature, the slope and ridge-width can be
precisely controlled.
3.   The ridge 1 has little or no etch damage which is an advantage
over other...