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Phase-Locked Laser Array Using Sublime Technology

IP.com Disclosure Number: IPCOM000100516D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 99K

Publishing Venue

IBM

Related People

Hodgson, RT: AUTHOR [+3]

Abstract

Disclosed is a method that uses the vacuum etching technology (*) to make accurate flats at angles 45 and 90 degrees to one another which makes phase-locked laser arrays in certain semiconductor materials possible. 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. (Image Omitted)

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Phase-Locked Laser Array Using Sublime Technology

       Disclosed is a method that uses the vacuum etching
technology (*) to make accurate flats at angles 45 and 90 degrees to
one another which makes phase-locked laser arrays in certain
semiconductor materials possible.  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.

                            (Image Omitted)

      The start of the new laser structure is shown in Fig. 1. A
blank <100> oriented gallium arsenide (GaAs) wafer 1 is polished so
that both sides are flat and parallel to within one-tenth wave.  The
wafer is coated with a number of layers of alternating aluminum
gallium arsenide (AlGaAs) layers 2 and GaAs layers 3 (of thickness of
one-quarter wavelength of the laser light in the semiconductor
material) which act as a multilayer dielectric mirror 4.  Then, a
layer of AlGaAs 5 is deposited to act as an etch stop for the vacuum
etching process, and a thicker layer of GaAs 6 is laid down.  Layers
of doped GaAs (n type) 7, p type indium gallium arsenide (InGaAs) 8,
and GaAs (p-type) 9 are grown which will act as the laser active
medium and confinement structure.

      Normal lithographic procedures are then used to produce a
number of rectangular islands of metal 10 on the surface of the wafer
lined up parallel with the <110> flat in the <100> wafer.  When the
wafer is introduced into a high vacuum and heated under a flux of
arsenic vapor, the surface which is not covered with the metal will
sublime to produce <110> planes 11 at 45 degrees to the original
plane of the wafer, as shown in Fig. 2.

      Then, a thin layer of crystal semi-insulating GaAs 12 can be
grown on all exposed semiconductor surfaces to inhibit surface
recombina...