Date of Graduation

5-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor/Mentor

Shui-Qing Yu

Committee Member

Gregory J. Salamo

Second Committee Member

Hameed A. Naseem

Third Committee Member

Simon S. Ang

Keywords

Applied sciences, Bismuth, Gaasbi, Iii-v semiconductor, Molecular beam epitaxy, Quantam well, Surfactant

Abstract

This dissertation explores modeling, molecular beam epitaxy growth, and fabrication of III-V bismide optoelectronic devices, which are of great importance in modern applications of telecommunication, gas sensing, environment monitoring, etc. In the current room-temperature continuous-wave operational GaSb-based type-I InGaAsSb/AlGaInAsSb quantum well laser diodes in 3-4 um mid-wavelength range, the lasing wavelength and performance of the devices are limited due to the lack of hole confinement in the active regions. In this dissertation, a novel GaSb-based GaInAsSbBi material is proposed to replace the conventional InGaAsSb material in the quantum well region, which enables the laser diodes achieve up to 4 µm optical transition wavelength with significantly enhanced hole confinement. Moreover, quasi-Al-free laser diode designs are realized for the first time in this wavelength range by employing GaInAsSbBi/GaSb active region and InGaAsSb cladding layers, which considerably improves the reliability of the laser diodes. In addition, GaInAsSbBi material is proposed to be used for high efficiency thermophotovoltaic devices. It provides narrower bandgap than traditionally InGaAsSb material so that more low-energy photons can be utilized during the energy conversion to achieve higher effiency. In the development of GaAsBi/GaAs temperature-insensitve optoelectronic devices, laser diodes have not been realized due to the lack of separate confinement heterostructures, which is bottlenecked by the difficulty of growing high quality AlGaAs barrier layers at low temperatures. In this work, we systematically investigate the effects of Bi during the growth of GaAsBi and propose Bi-mediated growth to grow high quality AlGaAs at low temperatures. GaAsBi/GaAs/AlGaAs single quantum well and double quantum well separate confinement heterostructures with excellent structural and optical properties are grown using molecular beam epitaxy with the upper AlGaAs layers grown at 320 °C. The surfactant effect of Bi is evidenced by the presence of a (1×3) surface reconstruction throughout the growth of AlGaAs. The Bi surfactant mediated growth of AlGaAs at low temperatures is reported for the first time. Process flows and photomasks are developed to fabricate optoelectronic devices. The capability and flexibility of the processes are successfully demonstrated by the fabrication of high performance GaAs quantum well laser diodes and InAs quantum dots light emitting diodes.

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