1.3um VCSELs using InGaAs/GaPAsSb Type-II Quantum Wells Grown on GaAs

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1.3-mm vertical-cavity surface-emitting laser (VCSEL) is an enabling device for future optical 10Gbit Ethernet and local area network. In the present proposal, we propose a novel approach to make 1.3 mm VCSELs on GaAs substrates with a single step epitaxial growth. The basic idea is to use an InxGa1-xAs/GaPyAszSb1-y-z/InxGa1-xAs type-II quantum well (QW) structure as the active region. Our preliminary theoretical and experimental studies of the proposed type-II QW structure have shown that the idea is feasible. A detailed theoretical model has been used to calculate the transition energies, overlaps between electron and hole wavefunctions, and gain spectra for the type-II QW structures. The results show that a gain of 8000 cm-1 can be reached under an electric injection of 10.1018 cm-3. Based on the theoretical design, several test samples for photoluminescence and LED structures have been grown by a specially configured molecular beam epitaxy (MBE) machine. TEM images clearly show well-defined QW structures. Strong room temperature photoluminescence from the QW samples and electroluminescence from the LEDs have been clearly observed. In the present proposed program, we will focus on three major tasks: 1) Further detailed theoretical modeling of gain spectra and optimized device structures of different variation of the proposed InGaAs/GaPAsSb type-II QWs; 2) MBE growth and materials characterization of the new QW structures to understand various growth related issues and find the optimized growth conditions for the VCSELs; 3) Detailed physics study of the carrier life time and optical properties of the InGaAs/GaPAsSb type-II QWs using low temperature cw and time resolved photoluminescence spectroscopy; 4) Device demonstration of cw VCSELs.In the proposed program, 2 PhD students will be supported. There will be also several undergraduate students to be involved in part of the program through their senior design projects.