The Study On Ⅲ-Ⅴ Group Material Growth Of Quantum Structure And Correlational Spintronics

Firstly, the theory and fabrication of molecular beam epitaxy(MBE) are described in detail. The surface morphology of InSb/GaAs quantum dot was studied by using atomic force microscopy (AFM). A series of high Al composition AlGaAs films at GaAs (110) substrate grown by MBE were investigated by using room temperature photoluminescence spectra, high resolution X-ray diffraction and low temperature photoluminescence spectra. Secondly, when the GaAs epitaxial layer grows on the GaAs (110) substrate, the single and double periods of RHEED intensity oscillation will be changed under different growth conditions. By means of RHEED oscillations, high quality quantum wells grown on GaAs (110) have been found under optimized growth conditions. The influence of different growth conditions on electron spin relaxation time in GaAs/AlGaAs (110) quantum wells (QWs) grown by MBE has been investigated by grazing incidence x-ray reflectivity, time-resolved Kerr rotation spectroscopy(TRKR), transmission electron microscope(TEM) and photoluminescence spectra. Lastly, we observed the inverse spin Hall effect in AlGaAs/InGaAs quantum wells sample at the room temperature by the time and spatially resolved Kerr rotation spectroscopy. The main content is as follows:1. The surface morphology of InSb/GaAs quantum dot was studied by using AFM. The varied monolayers(MLs) quantum dots were grown on the GaAs substrate, the density of InSb quantum dots increased as the increasing monolayers. The density of InSb quantum dots reached the maximum when the growth thickness was 2.5ML. As the growth thickness of quantum dots beyond 2.5ML, the quantum dots began to merge, the density of the quantum dots decreased and the size of quantum dots increased.2. The growth temperatures and As2/Ga beam equivalent pressure ratios (BEP) have an important impact on the growth of high Al composition A10.4Ga0.6As films at GaAs (110) substrate with high crystal quality and good optical property. In this report, we grown a series of samples with different growth temperatures and different BEP ratios on GaAs (110) substrates by molecular beam epitaxy. The samples were investigated by using room temperature photoluminescence spectra, high resolution X-ray diffraction and low temperature photoluminescence spectra. Then, the optimized growth condition was found on the growth of A10.4Ga0.6As films at GaAs (110) substrates.3. When the GaAs epitaxial layer grows on the GaAs (110) substrate, there are two growth modes (monolayer-by-monolayer and bilayer-by-bilayer) under different conditions that correspond to monolayer and bilayer RHEED (Reflection High Energy Electron Diffraction) oscillations. The measurements of transmission electron microscope and photoluminescence at room temperature showed that the quantum wells had very bad optical property under the bilayer-by-bilayer growth mode, while the quantum wells grown under the monolayer-by-monolayer growth mode had much better optical property with rough interfaces. By means of RHEED oscillations, high quality quantum wells grown on GaAs (110) have been found under optimized growth conditions.4. The influence of interface growth interruption on electron spin life time t in GaAs/AlGaAs (110) quantum wells (QWs) grown by solid source molecular beam epitaxy (SSMBE) has been investigated by grazing incidence x-ray reflectivity and time-resolved Kerr rotation spectroscopy (TRKR). The growth interruption at inverted (GaAs-on-AlGaAs) interface had a more impact on electron spin life time in QWs than that at normal (AlGaAs-on-GaAs) interface. Various inverted interface interruption time were used in growing QWs. Interface roughness of these QWs samples was studied by grazing incidence x-ray reflectivity. The simulated results of reflectivity curves by standard software indicated that interface roughness decreased as the interface growth interruption time increased. TRKR measurements at room temperature showed that the appropriate growth interruption could increase spin life time in GaAs/AlGaAs QWs drastically. This dramatic increase was explained by the suppression of the D'yakonov-Perel' interaction.5. Multi-terminal device of Hall bar geometry was patterned in the AlGaAs/InGaAs quantum wells sample by using the standard photolithography and wet etching. We observed the inverse spin Hall effect in the sample at the room temperature by the time and spatially resolved Kerr rotation spectroscopy. The inverse spin Hall effect complements the spin Hall effect, demonstrating the possibility of charge transport driven by the spin degrees of freedom. This effect is of great significance to the development of semiconductor spin electric devices.