Browse Prior Art Database

Manufacturable Gallium Nitride Power Laser Design/Process

IP.com Disclosure Number: IPCOM000118279D
Original Publication Date: 1996-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 158K

Publishing Venue

IBM

Related People

Strite, SC: AUTHOR

Abstract

Gallium Nitride (GaN) lasers will find broad use in the Ultra Violet (UV), blue and green wavelengths in both high power and low power applications. However, the development of GaN lasers has been severely limited by the high defect density in heteroepitaxial films and the high p-type ohmic contact resistance. Below, a fabrication process and device design is disclosed which allows a large area p-type ohmic contact to be used to inject current into a smaller active region. This design will greatly reduce the limitations that poor p-type contact resistivities place on present day GaN lasers while improving performance further by providing lateral current confinement.

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Manufacturable Gallium Nitride Power Laser Design/Process

      Gallium Nitride (GaN) lasers will find broad use in the Ultra
Violet (UV), blue and green wavelengths in both high power and low
power applications.  However, the development of GaN lasers has been
severely limited by the high defect density in heteroepitaxial films
and the high p-type ohmic contact resistance.  Below, a fabrication
process and device design is disclosed which allows a large area
p-type ohmic contact to be used to inject current into a smaller
active region.  This design will greatly reduce the limitations that
poor p-type contact resistivities place on present day GaN lasers
while improving performance further by providing lateral current
confinement.

      GaN lasers based largely on conventional heterojunction diode
laser design concepts have been successfully demonstrated.  Known GaN
lasers differ primarily from typical GaAs-based lasers through the
use of a non-conductive substrate which necessitates that ohmic
contacts of both polarities be formed above the substrate plane.
However, GaN lasers suffer from special design difficulties, and
would benefit from  improved structures developed specifically with
these challenges in mind.  For example, the performance of GaN-based
lasers to date is degraded by the large defect density present as a
result of heteroepitaxy, and the large p-type ohmic contact
resistances resulting  from the low (10 sup 17 cm sup -3) attainable
p-type doping levels in GaN.

      The Figure is a layer schematic of the proposed GaN-based
heterojunction diode laser.  The p-type side of the active region
comprising the upper layers of the laser structure is of particular
concern.  Ion implantation can be used to modify the electrical
properties of the initially p-type material beneath the surface on
either side of the active region, while leaving the uppermost
material largely unaltered.  Ion implantation of e.g., He, N or Ar is
known to compensate GaN with deep defects resulting in highly
insulating material.  By choosing the correction energy and species,
a highly insulating layer of GaN can be formed beneath the epitaxial
layer surface.  With a simple shadow mask approach, a center region
can be left  unaffected by the ion implantation.

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