The Research On The Approaches And The Technology Of Heterogeneous Compatible Integrated Micro-System

In the past decade, information industry developed rapidly, thus the optical communications systems are facing a huge challenge. The emitters and the receivers used in the optical communications system contain many optoelectronic devices. Therefore, the performances of optoelectronic devices play an important role in determining the overall performance of optical communications system. In order to improve the performance of optical communications system, the optoelectronic devices are integrated into one single chip, that is, optoelectronic integration, and the optical communications system becomes integrated micro-system. The advancement of integrated micro-system is obvious. First, the system is small and light-weight, so it is convenient. Second, the system does not contain the links between each single optoelectronic devices, so it is more stable. Third, it is low-energy consumption.The thesis is aimed at the optoelectronic integration, and investigates the three approaches for integrated micro-system:GaAs/Si metamorphic epitaxy, InAs/GaAs self-assembled quantum dots and boron containing semiconductor materials. The details are listed as follow:1. The research on the GaAs/Si metamorphic epitaxy:optimizing the growth parameters (including the growth temperature and the thickness of low-temperature nucleation layer, the growth temperature of high-temperature epitaxial layer). The three-step growth was employed. The first step is the growth of the low-temperature nucleation layer (420℃); the second step is a layer grown at an intermediate temperature (630℃); the third step is the high-temperature layer (685℃). The surface roughness of GaAs epitaxy layer decreases from3.6nm to2.6nm through the three-step growth. Based on the three-step growth, the cyclic annealing was employed. The surface roughness was decreased to1.8nm, and the etch pit density decrease to106/cm2from108/cm2.2. Based on the research of GaAs/Si metamorphic epitaxy, the epitaxial structure of GaAs/InGaAs self-rolled microtube was grown on the metamorphic GaAs epitaxial layer, and the good-quality microtubes array was fabricated successfully.3. The growth of InAs/GaAs self-assemble QDs was investigated:optimizing the growth rate of InAs QDs, Ⅴ/Ⅲ ratio, growth temperature, the thickness of overgrown layer. Based on the optimization, stacked QDs were grown. GaAs0.5P0.5layer was used as the strain compensation layer to eliminate the strain accumulation, the PL intensity therefore increase with the increase of QDs layer. In addition, InGaAs strain reduction layer was employed to elongate emission wavelength.4. Based on the researches of GaAs/Si metamorphic epitaxy and quantum dots, InAs/GaAs QDs were grown on the metamorphic GaAs epitaxial layer. It was found that the InAs QDs on the metamorphic layer is bigger than the QDs on GaAs substrate. Furthermore, the stacked QDs were used to block or terminate the threading dislocation. However, new dislocations nucleate around the big islands. As a result, the etch pits density increases to10/cm although the stacked QDs have terminates the threading dislocation significantly.5. The lattices and band structures of boron-containing quaternary materials can be adjusted more flexibly than ternary materials, so it might be another way to realize the monolithic integration. As foreshadows, the BGaAs ternary compounds were grown by using TEGa and TMGa as the gallium source. It was found that the BGaAs compound can be grown at a lower temperature of500℃, and a boron content of5%can be obtain if the gallium source is TEGa, but only3%with TMGa.6. BInGaAs/GaAs highly strained quantum wells were grown and their optical properties were studied. It was found that boron incorporation can reduce the compressive strain of the MQW structure significantly. For the InGaAs/GaAs and BInGaAs/GaAs structures with nearly same emission wavelength, the latter has significantly less compressive strain; and the emission wavelength of BInGaAs/GaAs structure is red-shifted compared to the corresponding InGaAs/GaAs structure with the same compressive strain value.7. The BGaAsSb thick layers and BGaAsSb/GaAs quantum wells were grown and studied in detail. It was found that boron incorporation can improve the Sb-incoporation efficiency. In the process of the growth of antimonide, part of Sb element stay on the surface of the film in the form of liquid metal, and limit the incorporation of Sb element. This is called Sb surface segregation effect. In this work, the Sb segregation effect decreases when boron is incorporated into the GaAsSb thick layer, thus more Sb incorporation and a higher compressive strain have been achieved. Similarly, boron incorporation can improve the Sb-incorporation efficiency and red-shift the emission wavelength of the quantum wells.