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Title:Integrable and Integrated Optoelectronic Devices Grown by Metalorganic Chemical Vapor Deposition
Author(s):Cockerill, Timothy Michael
Doctoral Committee Chair(s):Coleman, J.J.,
Department / Program:Electrical Engineering
Discipline:Electrical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Electronics and Electrical
Abstract:This thesis describes several integrable and integrated optoelectronic devices grown by metalorganic chemical vapor deposition (MOCVD) crystal growth. The emphasis is on device design and fabrication using crystal growth techniques to minimize post-growth processing and add design flexibility.
Single quantum well heterostructure lasers are characterized by high quantum efficiency, low threshold current, high output power, and quantum size effect wavelength selectivity. Thin single well lasers are also characterized, however, by relatively small near-field spot size and large beam divergence in the direction perpendicular to the junction plane. A novel single quantum well heterostructure laser has been developed, the graded barrier depressed index cladding laser, in which the perpendicular divergence angle is decreased while a reasonable threshold current density is maintained. This device is fabricated via a single MOCVD growth step.
The ability to grow the epitaxial layers of a partial structure, pattern the wafer, and subsequently regrow epitaxial layers of sufficient quality on the patterned sample allows for many novel device designs. To characterize the regrowth, its effect on the performance of strained-layer $\rm In\sb{x}Ga\sb{1-x}As$-GaAs separate confinement quantum well heterostructure lasers emitting near 985 nm is studied by using the optical emission of the laser as a probe of the epitaxial regrowth. Additionally, single-mode, strained-layer AlGaAs-GaAs-InGaAs lasers operating at a wavelength of 980 nm have been fabricated by two-step MOCVD.
Selective-area MOCVD growth and regrowth add additional design flexibility to the regrowth process. Growth rate enhancement from a silicon dioxide mask is the mechanism used for the selective-area growth rate enhancement. By varying the width of the oxide stripe opening, differences in the growth rate yield different quantum well thicknesses. This provides in-plane band-gap energy control, an essential part of optoelectronic integrated circuit design. Selective-area epitaxy has been used for wavelength tuning of strained-layer InGaAs-GaAs-AlGaAs quantum well lasers, yielding a wavelength range of over 600 A for lasers grown on the same substrate.
A monolithically integrated strained-layer InGaAs-GaAs-AlGaAs quantum well laser/passive waveguide has been grown by three-step conventional atmospheric pressure MOCVD selective-area growth and regrowth. Variation in the width of the oxide stripe opening along the length of the device results in different quantum well thicknesses, allowing the light generated in one selective growth region to propagate without significant absorption loss in an adjacent passive waveguide region.
Index-guided lasers are attractive for their modal stability and low threshold current. Selective-area epitaxy has been used to fabricate a strained-layer InGaAs-GaAs-AlGaAs buried heterostructure quantum well laser with low threshold currents.
Issue Date:1993
Description:95 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993.
Other Identifier(s):(UMI)AAI9411597
Date Available in IDEALS:2014-12-16
Date Deposited:1993

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