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Suppression of Current Leakage in Semiconductor Laser Diodes

IP.com Disclosure Number: IPCOM000112012D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Jakubowicz, A: AUTHOR [+3]

Abstract

Current leakage is a serious drawback of semiconductor laser diodes. Not only an important part of the injected current is lost and does not contribute to the lasing process, but also current leakage affect strongly operation parameters such as threshold, efficiency, lifetime and thermal resistance. Also, reliability can be affected.

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Suppression of Current Leakage in Semiconductor Laser Diodes

      Current leakage is a serious drawback of semiconductor laser
diodes.  Not only an important part of the injected current is lost
and does not contribute to the lasing process, but also current
leakage affect strongly operation parameters such as threshold,
efficiency, lifetime and thermal resistance.  Also, reliability can
be affected.

      The leakage is due to a bad confienment of the current in the
active region.  Therefore, only part of it contributes to the lasing
process (Fig. 1).

      The leakage can be suppressed by improving the confinement of
the current in the vicinity of the active region.  This is achieved
by replacing the normal planar backside contact of the laser by a
tip-like contact (Fig. 2).  Due to the "tip-effect", the current near
the tip is contracted and directed towards the extremity of the tip
(Fig. 2).

      After standard laser fabrication of the top side of the wafer,
a photolithographic mask is formed on the wafer backside aligned to
the front side.  This mask leaves openings underneath the active
laser areas.  Using wet etching, V-grooves are etched into the GaAs
wafer through the mask openings.  The etching process can be
performed in such a way that it effectively stops at the A1GaAs
cladding layer or at a layer purposely introduced into the vertical
epitaxial structure.

      After removal of the etching mask, a backside metal contact is
eva...