Search results for "molecular beam epitaxy"
showing 10 items of 73 documents
Photoluminescence and Raman spectroscopy of MBE‐grown InN nanocolumns
2008
InN nanocolumns grown under different conditions by plasma-assisted molecular beam epitaxy on p-Si (111) substrates are studied by micro-Raman and photoluminescence (PL) spectroscopies. The nanocolumns are free of strain and have an improved crystal quality as shown by the frequency and linewidth of the nonpolar E2h mode. Uncoupled polar modes coexist with a couple LO phonon-plasmon mode and are sensitive to the nanocolumn morphology. Variations in the growth conditions also modify the PL spectra significantly. An increase in the PL energy also involves a reduction of the integrated intensity and an increase of the PL linewidth. This overall phenomenology highlights the role of the surface …
Consequences of the spatial localization on the exciton recombination dynamics in InGaP/GaAs heterostructures
2002
5 páginas, 4 figuras.
Current status of AlInN layers lattice-matched to GaN for photonics and electronics
2007
We report on the current properties of Al1-x InxN (x approximate to 0.18) layers lattice- matched ( LM) to GaN and their specific use to realize nearly strain- free structures for photonic and electronic applications. Following a literature survey of the general properties of AlInN layers, structural and optical properties of thin state- of- the- art AlInN layers LM to GaN are described showing that despite improved structural properties these layers are still characterized by a typical background donor concentration of ( 1 - 5) x 10(18) cm(-3) and a large Stokes shift (similar to 800 meV) between luminescence and absorption edge. The use of these AlInN layers LM to GaN is then exemplified …
Optical characterization of individual GaAs quantum dots grown with height control technique
2013
We show that the epitaxial growth of height-controlled GaAs quantum dots, leading to the reduction of the inhomogeneous emission bandwidth, produces individual nanostructures of peculiar morphology. Besides the height controlled quantum dots, we observe nanodisks formation. Exploiting time resolved and spatially resolved photoluminescence we establish the decoupling between quantum dots and nanodisks and demonstrate the high optical properties of the individual quantum dots, despite the processing steps needed for height control. © 2013 AIP Publishing LLC.
Impact of kinetics on the growth of GaN on graphene by plasma-assisted molecular beam epitaxy.
2019
International audience; The growth of GaN on graphene by molecular beam epitaxy was investigated. The most stable epitaxial relationship, i.e. [00.1]-oriented grains, is obtained at high temperature and N-rich conditions, which match those for nanowire growth. Alternatively, at moderate temperature and Ga-rich conditions, several metastable orientations are observed at the nucleation stage, which evolve preferentially towards [00.1]-oriented grains. The dependence of the nucleation regime on growth conditions was assigned to Ga adatom kinetics. This statement is consistent with the calculated graphene/GaN in-plane lattice coincidence and supported by a combination of transmission electron m…
Physical properties and applications of InxGa1−xN nanowires
2014
We have successfully grown InxGa1−xN nanowires by plasma-assisted molecular beam epitaxy on silicon substrates. The alloy composition and crystal quality have been analyzed by Raman scattering, photoluminescence spectroscopy and x-ray fluorescence nanoprobe techniques. InxGa1−xN is an one-mode alloy, where the different optical modes have an intermediate frequency of that of pure InN and GaN. The sample composition can be derived from the Raman data. On the other hand, by using the optical gap provided by the emission spectra, we conclude that the samples have a lower Ga content than that provided by the Raman analysis. X-ray fluorescence maps and photoluminescence measured in single nanowi…
Optical properties of nitride nanostructures
2010
In this paper we review some recent results on the optical properties of nitride nanostructures, in particular on GaN quantum dots (QDs) and InN nanocolumns (NCs). First, we will give a brief introduction on the particularities of vibrational modes of wurtzite. The GaN QDs, embedded in AlN, were grown by molecular beam epitaxy (MBE) in the Stransky-Krastanov mode on c- and a-plane 6H-SiC. We have studied the optical properties by means of photoluminescence (PL) and performed Raman scattering measurements to analyze the strain relaxation in the dots and the barrier, the effect of the internal electric fields, and the influence of specific growth parameters, like the influence of capping or t…
Influence of the InAs coverage on the phonon-assisted recombination in InAs/GaAs quantum dots
2002
6 páginas, 3 figuras.
Single photon emission from impurity centers in AlGaAs epilayers on Ge and Si substrates
2012
We show that the epitaxial growth of thin layers of AlGaAs on Ge and Si substrates allows to obtain single photon sources by exploiting the sparse and unintentional contamination with acceptors of the AlGaAs. Very bright and sharp single photoluminescence lines are observed in confocal microscopy. These lines behave very much as single excitons in quantum dots, but their implementation is by far much easier, since it does not require 3D nucleation. The photon antibunching is demonstrated by time resolved Hanbury Brown and Twiss measurements.
Spontaneous core–shell elemental distribution in In-rich In(x)Ga1-xN nanowires grown by molecular beam epitaxy.
2014
International audience; The elemental distribution of self-organized In-rich InxGa1-xN nanowires grown by plasma-assisted molecular beam epitaxy has been investigated using three different techniques with spatial resolution on the nanoscale. Two-dimensional images and elemental profiles of single nanowires obtained by x-ray fluorescence and energy-dispersive x-ray spectroscopy, respectively, have revealed a radial gradient in the alloy composition of each individual nanowire. The spectral selectivity of resonant Raman scattering has been used to enhance the signal from very small volumes with different elemental composition within single nanowires. The combination of the three techniques ha…