Vertical-Cavity Laser Diodes Fabricated by Phase - Epitaxy.
Abstract
The fabrication of vertical-cavity surface-emitting laser diodes (VCSELs) has challenged the capabilities of conventional thin film growth techniques such as MBE because of the stringent requirements on layer thickness and interface flatness required to produce high reflectivity AlGaAs Bragg reflectors. This dissertation presents a new growth technique for the fabrication of VCSELs that is based on phase-locked epitaxy (PLE) and that addresses the problems associated with the growth of these structures. The techniques presented here are the first to extend PLE toward the fabrication of precision macroscopic structures such as VCSELs. Experimental and theoretical analysis show that PLE-grown Bragg reflectors have a maximum error in layer periodicity of 1%, and a maximum loss due to optical scattering of 0.01% per interface. In addition, 1.5% uniformity in layer thickness across a 50 mm wafer is achievable. Because the PLE growth technique solves the thin -film growth problems that have hampered VCSEL development, it has been possible to fabricate extremely high quality lasers. The lasers presented here were the first to be fabricated using an in situ feedback technique to control layer thickness. They were also the first VCSELs to lase in the 10 mW CW power range, the first to utilize lower aluminum content mirrors to control series resistance, and the first with low threshold voltages (1.6 V). Furthermore, this growth technique is capable of growing high quality VCSEL wafers within tight tolerances and with near 100% yields on both single-wafer and wafer-to-wafer scales. In addition to results from VCSELs fabricated by PLE, a new type of integrable device called a deformable Fabry-Perot (DFP) cavity is proposed. The DFP has potential applications for broadly-tunable surface-normal detectors and lasers for wavelength division multiplexing. Theoretical analysis indicates 50 nm wavelength tunability with a 10 V applied bias. Finally, a new type of AlGaAs multiple quantum well 5-20 μm mid-infrared detector is proposed. The device uses modification of the conduction band wave functions to allow for the absorption of normal incidence light. Theoretical analysis shows the ability to achieve 1000 cm^{-1} absorption.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1993
- Bibcode:
- 1993PhDT.......148W
- Keywords:
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- Physics: Condensed Matter; Engineering: Electronics and Electrical; Physics: Optics