Yang Chengliang

Growth, Antimony Incorporation Behaviour and Beryllium Doping of GaAs1-ySby Grown on GaAs by Molecular Beam Epitaxy

A series of GaAs1-ySby epilayers are grown on GaAs substrates under different growth conditions. Different antimony compositions of samples with beryllium doping are obtained. A non-equilibrium thermodynamics model is used to calibrate and fit the Sb composition. Activation energy of 0.37eV for the dissociation process of Sb4 molecules is obtained. Carrier mobility and concentration of samples are influenced by the Sb composition. Quasi-qualitative analysis of mobility is used to explain the relations among Sb composition, carrier mobility and concentration. High resolution x-ray diffraction (HRXRD) rocking curves and Hall effects measurements are used to determine the crystal quality, carrier mobility and concentration.

Advancement of adaptive optics in astronomical observation

Adaptive optics is used to compensate the atmospheric turbulence aberration for diffractive limit images, which makes the angular resolution of large aperture telescope not limited by the seeing or atmospheric coherence length. The continuous improvements of wavefront sensing, correctors and enlarged FOV for adaptive optics accelerate the development of astronomy. The main adaptive optics techniques include classical FOV and high resolution astronomical observation, extro-planet observation and solar observations and so on. And they have different technique requirements for adaptive optics. In the paper, we give some summarization and expectation of the advancement in the above three fields, especially in some new elemental techniques in detail, which will be helpful for our national adaptive optics development in large aperture telescopes.

Effect of GaAs/GaSb Combination Strain-Reducing Layer on Self-Assembled InAs Quantum Dots

Self-assembled quantum dots capping with a GaAs/Gasb combined strain-reduced layer (CSRL) are grown by MBE. Their structural and optical properties are investigated by AFM and photoluminescence (PL). PL measurements have shown that stronger emission about 1.3 μm can be obtained by Sb irradiation and capping QDs with 3 ML GaAs/2ML GaSb CSRL at room temperature. The full width at half maximum (FWHM) of the PL spectrum is about 20.2meV (19.9meV) at room temperature (20K), indicating that the QDs have high uniform, The result of FWHM is much better than the recently reported result, which is due to the fact that lower QD growth rate and growth interruption after the QDs deposition are adopted in our experiments.