Fabrication and analyses of intermixing in InGaAs/InGaAsP and InGaAsP/InP quantum welld and their use in intermixed quantum-well lasers and integrated laser-modulator structures

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Quantum-well intermixing relies on the creation of non-equilibrium concentrations of point defects that diffuse through the quantum wells and adjacent barrier layers during thermal-anneal treatment, causing changes in the quantum-well dimensions and composition. At present there are few direct compositional studies that look into redistribution of material inside quantum- well structures due to intermixing. It is proposed to use analytical electron microscopy to determine the compositional and morphological changes induced by quantum well intermixing in order to fabricate InP and GaAs-based quantum-well structures with spatial wavelength characteristics. The ability to observe temperature-dependent changes in the compositional profiles will permit the direct measurement of the diffusion of elements due to quantum-well intermixing and to determine the activation energies of the process. The effective diffusion coefficients obtained from the concentration profiles of annealed samples will lead to better understanding of the particular diffusion mechanism for each particular system (i.e. the substitutional-interstitial and the vacancy mechanisms under intrinsic point defect equilibrium and non-equilibrium conditions). Results will be compared with theoretical calculations based on photoluminescent- wavelength shift and, therefore, will significantly improve our knowledge of the diffusion and interdiffusion mechanisms that take place in semiconductor materials.The objective of this work is to tailor the optical properties of the materials in order to produce optoelectronic devices for use in a range of optoelectronic applications such as medical diagnostics and integrated optoelectronics. In particular, we will be initially concerned with the fabrication and processing of ridge-type integrated laser-modulator modules, which have potential applications in a wide range of high-speed optical-signal processing equipment. Later we will extend these studies to include integrated distributed feedback laser-modulator modules  Also, we will continue our studies on the reproducibility and long-term reliability of optoelectronic devices, and apply the knowledge to evaluate our fabricated devices.