4 research outputs found
On the quantum and classical scattering times due to charged dislocations in an impure electron gas
We derive the ratio of transport and single particle relaxation times in
three and two - dimensional electron gases due to scattering from charged
dislocations in semiconductors. The results are compared to the respective
relaxation times due to randomly placed charged impurities. We find that the
ratio is larger than the case of ionized impurity scattering in both three and
two-dimensional electron transport.Comment: 4 pages, 3 figure
On the Growth Mechanisms of GaAs Manowires by Ga-Assisted Chemical Beam Epitaxy
GaAs nanowires (NWs) growth kinetics by Ga-assisted chemical beam epitaxy on Si(111) substrates is studied as a function of the initial Ga catalyst dimensions and growth parameters such as substrate temperature and V/III flux ratio. The preparation method for substrates is optimized in order to obtain a surface oxide with a thickness around 0.5 nm, allowing the decomposition of Ga metalorganic precursor and the preferential growth of GaAs NWs at the oxide pinholes. The successful self-formation of Ga droplets over the slightly oxidized Si surface has been observed by scanning electron microscopy (SEM), whose initial size is demonstrated to affect both the NW growth rate and the resultant NW aspect ratio. NW morphology is thoroughly analyzed by SEM, showing a self-organized array of vertically aligned match-shaped GaAs NWs with a hexagonal footprint. In addition, the crystalline structure of NWs is monitored in-situ by reflection high-energy diffraction (RHEED), showing pure zincblende phase along the whole NW stem