Growth and characterizations of semiconductor quantum wires .

摘要

Semiconductor quantum wire (QWR) structure is a promising candidate for potential applications in long wavelength laser devices. In this thesis, the investigations were focused on the growth and characterization on the structural and optical properties of InAs quantum wires deposited on InGaAlAs lattice matched with InP substrate by gas source molecular beam epitaxy.Structural properties of the quantum wires were characterized by (scanning) transmission electron microscopy based techniques. The composition variation, elastic field and the variation of QWR stacking patterns in multilayer samples were qualitatively studied through diffraction contrast imaging. Quantification of the In distribution in individual QWRs and the QWR-induced In composition modulation in barrier layers were obtained by electron energy loss spectrometry and energy dispersive X-ray spectrometry, respectively. These experimentally observed structural features were explained through finite element simulations.The optical properties of the QWR structures were studied by photoluminescence. Optical emission at room temperature was achieved from selected multilayer QWR samples after etching and rapid thermal annealing. The emission wavelength ranging from 1.53 to 1.72 mum makes the QWR structure suitable candidates for laser device applications.This work contributes to the understanding of growth mechanism and the modeling on the physical properties of semiconductor QWR structures.The practical growth parameters were first determined by studying the samples containing single InAs layer embedded within In0.53Ga 0.37Al0.10As barrier layers. These parameters were then employed for fabricating multilayer quantum wires with different (1) spacer layer thicknesses (2) quantum wire layer thicknesses and (3) different Al concentrations in the spacer/barrier layer materials.