2019年6月20日星期四

Shape and size control of InAs/InP (113)B quantum dots by Sb deposition during the capping procedure

he role of Sb atoms present on the growth front during capping of InAs/InP (113)B quantum dots (QDs) is investigated by cross-sectional scanning tunnelling microscopy, atomic force microscopy, and photoluminescence spectroscopy. Direct capping of InAs QDs by InP results in partial disassembly of InAs QDs due to the As/P exchange occurring at the surface. However, when Sb atoms are supplied to the growth surface before InP capping layer overgrowth, the QDs preserve their uncapped shape, indicating that QD decomposition is suppressed. When GaAs0.51Sb0.49 layers are deposited on the QDs, conformal growth is observed, despite the strain inhomogeneity existing at the growth front. This indicates that kinetics rather than the strain plays the major role during QD capping with Sb compounds. Thus Sb opens up a new way to control the shape of InAs QDs.


Source:IOPscience


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2019年6月14日星期五

Effects of growth temperature and metamorphic buffer on electron mobility of InAs film grown on Si substrate by molecular beam epitaxy

The growth of the InAs film directly on the Si substrate deflected from the plane (100) at 4° towards (110) has been performed using a two-step procedure. The effect of the growth and annealing temperature on the electron mobility and surface topography has been investigated for a set of samples. The results show that the highest electron mobility is  in the sample, in which the 10-nm InAs nucleation layer is grown at a low temperature of 320 °C followed by ramping up to 560 °C, and the nucleation layer was annealed for 15 min and the second layer of InAs is grown at 520 °C. The influence of different buffer layers on the electron mobility of the samples has also been investigated, which shows that the highest electron mobility of  at 300 K is obtained in the sample grown on a thick and linearly graded InGaAlAs metamorphic buffer layer deposited at 420 °C.



Source:IOPscience

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2019年6月5日星期三

GaAsSb layer thickness dependence of arsenic incorporation on InAs/GaAsSb superlattice on InAs substrate grown by metalorganic vapor phase epitaxy for mid-infrared device

We investigated the gas flow sequence to realize a short-period and lattice-matched InAs/GaAsSb superlattice on an InAs substrate by metalorganic vapor phase epitaxy (MOVPE) growth for applications in mid-infrared photonic devices. The arsenic composition of GaAsSb for lattice matching was adjusted by adding AsH3 flow to residual arsenic incorporation. The growth conditions for lattice-matched superlattices at a period of 5 nm were found. The superlattices with period thicknesses of 1 to 9 nm were successfully confirmed by the photoluminescence (PL) peak in the range from 2.4 to 5 µm depending on layer thickness at 20 K. The emission wavelength can be controlled by changing the layer thickness of superlattices. The results led to the improvement of InAs/GaAsSb type II superlattice growth.



Source:IOPscience

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