Current confinement in a GaAs/AlGaAs heterostructure by i n s i t u laser-patterned desorption of a current-blocking quantum well

Abstract

Radiation from Ar+ and Nd:YAG lasers is used within a metalorganic chemical vapor deposition reactor to thermally desorb selected areas of GaAs quantum well (QW) layers during a pause in the epitaxial growth. The process, called laser-patterned desorption, is used to laterally pattern current confinement in an AlGaAs/GaAs diode laser structure. Current channels are produced by completely removing selected areas (∼3 mm wide) of an n+ GaAs QW blocking layer embedded in the AlGaAs p cladding of a separate confinement heterostructure laser. Scanning electron microscopy cross sections indicate the blocking layer is completely removed in regions illuminated with the focused laser beam. Current confinement is confirmed by observing the localized optical emission from a 1-cm-long bar containing a 1-mm-wide desorbed region. Broad-area diode lasers fabricated from the sample exhibit a forward voltage varying from a minimum (∼2 V) within the lase-desorbed region to a maximum (∼4 V) in the surrounding field. This work is the first demonstration of current confinement produced by epitaxial patterning in an optical device during growth.