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The mid-wave single-crystal HgCdTe (211) films were successfully grown on GaAs (211) B substrates by molecular beam epitaxy (MBE). Microstructure and optical properties of the MBE growth HgCdTe films grown at different temperatures were characterized by X-ray diffraction, scanning transmission electron microscopy, Raman and photoluminescence. The effects of growth temperature on the crystal quality of HgCdTe/CdTe have been studied in detail. The HgCdTe film grown at the lower temperature of 151 °C has high crystal quality, the interface is flat and there are no micro twins. While the crystal quality of the HgCdTe grown at higher temperature of 155 °C is poor, and there are defects and micro twins at the HgCdTe/CdTe interface. The research results demonstrate that the growth temperature significantly affects the crystal quality and optical properties of HgCdTe films.

In this work, CdTe(0 0 1) and CdTe(1 1 1) single-crystal films were successfully grown on GaAs(0 0 1) substrates by molecular beam epitaxy. By changing the nucleation temperature, CdTe(0 0 1) and (1 1 1) films could be controllably grown on the GaAs(0 0 1) substrates. The CdTe(0 0 1) and (1 1 1) films were grown via low-temperature nucleation followed by high-temperature growth. To optimize the quality of CdTe(0 0 1) films, a CdTe/ZnTe superlattice was used to reduce the lattice mismatch, and the CdTe(0 0 1) film was grown under a cadmium-rich atmosphere. The average surface roughness of the CdTe(1 1 1) and CdTe(0 0 1) films produced was approximately 0.76 nm and 1.37 nm, respectively. The epitaxial relationship between the CdTe(1 1 1) film and the GaAs(0 0 1) substrate was studied based on X-ray diffraction pole figures. The crystal quality of the CdTe(1 1 1) film was also characterized by X-ray diffraction and etch pit density. Finally, photoluminescence spectroscopy was used to investigate the crystal quality of CdTe(0 0 1) and (1 1 1). When the CdTe(0 0 1) film was grown under a cadmium atmosphere and using ZnTe as a buffer layer, the X-ray diffraction peak around 1.56 eV disappeared; this can be related to cadmium vacancies.

Strained HgTe thin films are typical three-dimensional topological insulator materials. Most works have focused on HgTe (100) films due to the topological properties resulting from uniaxial strain. In this study, strained HgTe (111) thin films are grown on GaAs (100) substrates with CdTe (111) buffer layers using molecular beam epitaxy (MBE). The optimal growth conditions for HgTe films are determined to be a growth temperature of 160°C and an Hg/Te flux ratio of 200. The strains of HgTe films with different thicknesses are investigated by high-resolution x-ray diffraction, including reciprocal space mapping measurements. The critical thickness of HgTe (111) film on CdTe/GaAs is estimated to be approximately 284 nm by Matthews’ equations, consistent with the experimental results. Reflection high-energy electron diffraction and high-resolution transmission electron microscopy investigations indicate that high-quality HgTe films are obtained. This exploration of the MBE growth of HgTe (111) films provides valuable information for further studies of HgTe-based topological insulators.

Education and economy are the two main themes of social development. This article makes a statistical analysis of the two indicators of the number of college students and the actual GDP in Fujian Province in 1978-2013.Next, we analyze the time series relationship between higher education and economic growth in Fujian province. The results show that there is a strong correlation between the two. Under the certain conditions, there is a one-way causal relationship between the two.

surface using STM yielded appreciably different results. It is observed that the threshold pulse voltage is lower than that for graphite at comparable tunneling conditions. The minimum dimension of the as-produced features is appreciably larger than those on graphite. Both observations indicate higher surface instability for 1TTaS2 as compared with graphite.

Atomic force microscopy (AFM) measurements of nanometer-sized islands formed by 2 monolayers of InAs by molecular beam epitaxy have been carried out and the scan line of individual islands was extracted from raw AFM data for investigation. It is found that the base widths of nanometer-sized islands obtained by AFM are not reliable due to the finite size and shape of the contacting probe. A simple model is proposed to analyze the deviation of the measured value From the real value of the base width of InAs islands. (C) 1998 Elsevier Science B.V. All rights reserved.

To construct retroviral vector bringing HSV-tk gene under control of human AFP enhancer core sequence and human pgk promoter.Internal SV40 promoter was deleted by SalI from retroviral vector pMNSM to construct pMNM. HSV-tk gene driven by pgk promoter was released by BamH I from an eukaryotic expression vector pBPGK-tk, and inserted into polylinker site of pMNM to construct pMNP-tk retroviral vector. Human α-fetoprotein gene enhancer core sequence was released by EcoR I from pGEM. 7Z-AFPe plasmid was inserted into the immediate upstream of pgk promoter of pMNP-tk vector. Construction of hepatoma specific retroviral vector pMNAP-tk was completed.The structure of pMNP-tk and pMNAP-tk vector was confirmed by restriction analysis.The vector is of great significance for hepatoma specific prodrug transformation gene therapy.