| As a typical representative material of III-V compound semiconductor materials,GaAs/AlGaAs quantum wells has been widely used in many fields because of its high carrier mobility,adjustable Al component and small lattice mismatch with GaAs.Especially,the heterojunction semiconductor material composed of GaAs/AlGaAs quantum wells is an important material for the fabrication of high performance laser detectors.However,the selection of structural parameters,the defects introduced in the growth and preparation of material and the interfacial characteristics of heterogeneous interfaces in material have seriously affected the performance of optoelectronic devices,which has become the focus of research in recent years.In this paper,GaAs/AlGaAs quantum well materials were prepared by molecular beam epitaxy(MBE)technique.The basis of the theory and experiment was constituted based on the selection of structure parameters before preparation and the characterization analysis after preparation,the effect of rapid thermal annealing on the overall quality of the material is studied by means of the interface control method of rapid thermal annealing,thus obtaining the best annealing condition.It provides basic materials and technical support for future optoelectronic devices such as semiconductor lasers and detectors based on GaAs/AlGaAs quantum well materials.The dissertation mainly includes three parts:(1)Using the quantum interference model to simulate the energy band distribution and QWIP detection wavelength of GaAs/AlGaAs quantum wells.On the premise of using the transition mechanism from bound state to quasi bound state,the detection wavelength of QWIP decreases with the increase of well width,increases with the increase of barrier width and decreases with the increase of Al component.According to the simulation results,the optimized structure parameters can be selected,which provides a theoretical basis for the later fabrication and application of material devices.(2)GaAs/AlGaAs multi-quantum wells were successfully fabricated using molecular beam epitaxy equipment.Characterization tests were performed by XRD to verify the accuracy of the structure parameters(period thickness,composition,etc.)and the growth quality of the grown multi-quantum wells.The peak source of the sample was obtained by using room temperature PL,and PL Mapping found that the original sample had poor luminescence uniformity.The surface morphology and surface roughness of the samples were observed by AFM characterization.The obtained samples have a root mean square roughness(RMS)of 0.576 nm.However,the surface morphology of the grown samples showed that there were a little island growth on the surface of the samples,which is mainly caused by the defects introduced in the growth process or the characteristics of the heterogeneous boundary surface,which results in the high roughness of the sample.(3)Thermal annealing interface control method was used to the grown MQW material.The optimal annealing temperature of 800? was obtained by the characterization of XRD and room temperature PL,compared with the original sample,the XRD diffraction intensity and the PL strength are increased by about 1 times,but the high temperature will make the material quality worse.Using room temperature PL,the band gap blue shifted about 10 meV when the annealing temperature was 900?,revealing that excessively high annealing temperature may cause the interfacial mixing effect of the sample,resulting in the reduction of the quantum confinement effect of the material and deteriorating the quality of the sample.PL mapping was used to verify the improvement of the luminescence uniformity of GaAs/AlGaAs multiple quantum wells by rapid thermal annealing.AFM results showed that the annealing temperature at 800 ? has an RMS of 0.23 nm,the surface roughness is much lower than that of the original sample,which is also verified that the annealing temperature at 800 ? can significantly improve the quality of multiple quantum well materials. |
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