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Self-Aligned Zn-Diffusion Process for Threshold Current Reduction of Visible Semiconductor Lasers

IP.com Disclosure Number: IPCOM000113018D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Deutsch, U: AUTHOR [+4]

Abstract

Using a zinc diffusion process, the threshold of visible ridge-waveguide semiconductor lasers can be reduced due to the current and carrier confinement of the injected current and the electron-hole pairs. The process can be easily implemented into the existing fabrication technology of ridge-waveguide laser devices with dry- or wet-etched ridges. Only two simple process steps have to be added to the process sequence of conventional ridge-waveguide laser devices, namely a zinc evaporation process before the silicon nitride is embedded and a heating process to diffuse the zinc into the active region. The zinc diffusion changes the material properties in two ways:

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Self-Aligned Zn-Diffusion Process for Threshold Current Reduction
of Visible Semiconductor Lasers

      Using a zinc diffusion process, the threshold of visible
ridge-waveguide semiconductor lasers can be reduced due to the
current and carrier confinement of the injected current and the
electron-hole pairs.  The process can be easily implemented into the
existing fabrication technology of ridge-waveguide laser devices with
dry- or wet-etched ridges.  Only two simple process steps have to be
added to the process sequence of conventional ridge-waveguide laser
devices, namely a zinc evaporation process before the silicon nitride
is embedded and a heating process to diffuse the zinc into the active
region.  The zinc diffusion changes the material properties in two
ways:

o   The III-components of the GaInP active layer are disordered
    leading to a bandgap which is increased by approximately 100 meV.
    (From 1.84 eV to 1.91 eV (670 nm to 650 nm)).  Therefore,
    electron-hole pair which are generated during the operation of
    the device are confined in the region of the optical mode.

o   During zinc diffusion the p-n junction is shifted down into the
    AlGaInP region with wider bandgap (GaInP has a bandgap of 1.84 eV
    and (AlxGa1-x)0.5In0.5P with an Al of x = 0.7 has a bandgap of
    2.2 eV).  Since the current flows through the regions with lower
    bandgap energy at the p-n junction (the current depends
    exponentially on...