Influence of Surface Structures on Quality of CdTe(100) Thin Films Grown on GaAs(100) Substrates

We report the epitaxial growth of single-crystalline Cd Te（100） thin films on Ga As（100） substrates using molecular beam epitaxy. By controlling the substrate pre-heated temperature with adjustable Te flux, three different reconstructed surfaces are realized, and their influence on the subsequent Cd Te growth is investigated. More importantly, we find that both the presence of a thin native oxide layer and the formation of Ga-As-Te bonds at the interface enable the growth along the（100） orientation and help to reduce the threading dislocations and other defects. Our results provide new opportunities for compound semiconductor heterogeneous growth via interfacial engineering.

Growth and Characterization of InSb Thin Films on GaAs(001) without Any Buffer Layers by MBE

We report the growth of InSb layers directly on GaAs （001） substrates without any buffer layers by molecular beam epitaxy （MBE）. Influences of growth temperature and V/Ⅲ flux ratios on the crystal quality, the surface morphology and the electrical properties of InSb thin films are investigated. The InSb samples with room- temperature mobility of 44600cm2/Vs are grown under optimized growth conditions. The effect of defects in InSb epitaxial on the electrical properties is researched, and we infer that the formation of In vacancy （VIn） and Sb anti-site （SbIn） defects is the main reason for concentrations changing with growth temperature and Sb2/In flux ratios. The mobility of the InSb sample as a function of temperature ranging from 90 K to 360K is demonstrated and the dislocation scattering mechanism and phonon scattering mechanism are discussed.

Fractional-dimensional approach for excitons in Ga As films on AlxGa(1-x)As substrates

Binding energies of excitons in GaAs films on AlxGal-xAs substrates are studied theoretically with the fractional- dimensional approach. In this approach, the real anisotropic ＂exciton ＋ film＂ semiconductor system is mapped into an effective fractional-dimensional isotropic space. For different aluminum concentrations and substrate thicknesses, the exci- ton binding energies are obtained as a function of the film thickness. The numerical results show that, for different aluminum concentrations and substrate thicknesses, the exciton binding energies in GaAs films on AlxGal_xAs substrates all exhibit their maxima with increasing film thickness. It is also shown that the binding energies of heavy-hole and light-hole excitons both have their maxima with increasing film thickness.

The Growth and Microstructure of GaAs Embedded with Al Nanocrystals

The preparation and the microstructure of GaAs embedded with Al nanocrystals prepared by Laser molecular beam epitaxy were investigated.The microstructure of the sample was observed by transmission electron microscope.The reflection high-energy electron diffraction(RHEED)pattern varied from the stripe pattern to the spot pattern at the beginning of the Al nanocrystals growth,and then the spot pattern tended to change to the stripe pattern.There was a large lattice mismatch between Al and GaAs substrate,and Al formed three-dimensional islands on the GaAs substrate,which led to the RHEED transformation into the spot pattern.Otherwise,the dislocations would be formed between the GaAs layer and Al islands due to the large lattice mismatch.Meanwhile,there was some polycrystal of GaAs around the Al islands.

Novel method to determine effective length of quantum confinement using fractional-dimension space approach

The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framework of the fractional-dimensional space approach. Using this scheme, we propose a new method to define the effective length of the quantum confinement. The limita- tions of the definition of the original effective well width are discussed, and the binding energy and effective mass of a polaron confined in a GaAs film are obtained. The fl-actional-dimensional theo- retical results are shown to be in good agreement with previous, more detailed calculations based on second-order perturbation theory.