Manufacturability of gallium arsenide/aluminum gallium arsenide lasers grown by molecular beam epitaxy
Iyer, Sridhar V.
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Permalink
https://hdl.handle.net/2142/19945
Description
Title
Manufacturability of gallium arsenide/aluminum gallium arsenide lasers grown by molecular beam epitaxy
Author(s)
Iyer, Sridhar V.
Issue Date
1994
Doctoral Committee Chair(s)
Ravaioli, Umberto
Department of Study
Electrical and Computer Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Engineering, Materials Science
Language
eng
Abstract
The performance of high-power graded index separate confinement heterostructure single quantum well lasers grown by molecular beam epitaxy depends primarily on the quality of $Al\sb{x}Ga\sb{1-x}As$ layers, the interface roughness, and the control of residual oxygen incorporation into the active region. Based on MBE growth experiments, a model for the incorporation, desorption and accumulation of oxygen during epitaxial growth of optical quality AlGaAs layers is proposed and validated. Based on this model, an optimal growth scheme for MBE grown GaAs/AlGaAs lasers is demonstrated. Over the growth of approximately one hundred and fifty lasers in a concurrent research, development, and manufacturing environment, the reduction of residual oxygen incorporation in GRINSCH-SQW lasers was found to be in excellent correlation with lower threshold density, higher quantum well photoluminesence intensity, and secondary ion mass spectroscopy data. The high growth temperatures required to prevent oxygen incorporation in the quantum well result in additional technical obstacles stymieing full exploitation of the growth technology for use in the manufacture of integrated opto-electronic circuits and systems. The inherent difficulties in accurately measuring growth temperature in MBE systems and the gallium desorption during high temperature growth can lead to nonuniformities in cladding material composition. These nonuniformities can lead to an asymmetrical waveguiding structure with distorted optical output characteristics. Distortions in the radiated optical pattern can greatly affect the alignment and coupling efficiency between laser diodes and optical fibers or other electro-optical systems in integrated opto-electronic applications. A two-dimensional dielectric waveguide simulator has been used to analyze the optical properties of GRINSCH GaAs/AlGaAs lasers with asymmetrical cladding structures induced by noise in growth temperature measurement. Through this analysis, an optimal device structure which has the desired optical characteristics and is less sensitive to cladding composition asymmetries is demonstrated.
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