GaAs/GaSb strained-layer heterostructures deposited by metalorganic vapor phase epitaxy (original) (raw)
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GaSb/GaAs heteroepitaxy characterized as a stress-free system
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Thin layers of GaSb grown on GaAs by molecular beam epitaxy have been studied by Raman spectroscopy and transmission electron microscopy. In spite of the high value of the lattice mismatch (8%), these systems reveal a good crystalline quality: as a matter of fact, the lattice dynamics analysed through the resonant Raman scattering lead to a large correlation length for the optical modes. Moreover, they evidence the unstrained nature of the epilayers. The absence of the residual strain is connected to the highly regular network of Lomer dislocations observed by TEM. Obtaining such a perfect array of dislocations is a consequence of both the characteristic of the system (high lattice mismatch, same cationic sites) and the peculiar growth conditions (ideal surface preparation due to the buffer layer, adequate temperature allowing the direct relaxation of GaSb by island growth).
A strain relief mode at interface of GaSb/GaAs grown by metalorganic chemical vapor deposition
Applied Physics Letters, 2011
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Journal of Materials Science: Materials in Electronics, 2016
Strain-relieved GaSb quantum dots on GaAs can be achieved by either periodic interfacial misfit (IMF) or the conventional Stranski-Krastanov (SK) growth modes by changing the growth parameters. In this study, the Sb interfacial treatment was employed to improve the GaSb crystal quality including low defect density, smooth surface morphology, and high hole mobility. This technique yields two-dimensional (2D) islands with a height as low as 1.7 nm and width up to 190 nm in the IMF growth mode. In contrast to the interfacial treatments conventionally employed in the initial strain relaxation of GaSb/GaAs hererostructure, the Sb treatment promotes the formation of strong Ga-Sb bonds on the surface of the grown island, which effectively reduces the interfacial free energy and thus promotes the formation of 2D islands. With the Sb interfacial treatment, a high-relaxation 100-nm GaSb epilayer was grown on the GaAs substrate, the epilayers was strain relaxed and exhibited enhanced electrical properties with a high hole mobility of *667 cm 2 V-1 s-1 and with superior optical properties as evidenced by the photoluminescence B-line peak. The results of this study demonstrate an effective interfacial-treatment growth technique to relax the initial strain for the highly mismatched GaSb layers grown on a GaAs substrate.
Optical properties of GaSbAlSb heterostructures grown by molecular beam epitaxy
Materials Science and Engineering: B, 1993
In the first part of this paper we discuss the optimization of the growth conditions of molecular beam epitaxy GaSb layers. Then we present preliminary results for GaSb-AlSb multiple quantum wells which have one excitonic absorption line peaking at about 1.5 #m at room temperature. Finally we present a 10 pair Bragg reflector which shows 97% reflectivity. These preliminary results allow the GaSb-AISb system to be considered for optoelectronic devices.
Dependence of the AlSb buffers on GaSb/GaAs(0 0 1) heterostructures
2007
The strain-relief and structural properties of GaSb films with thin AlSb islands and thick AlSb buffer layers grown on GaAs (0 0 1) substrate at low temperature (LT) by molecular beam epitaxy are investigated by atomic force microscopy and transmission electron microscopy. The strain arising from depositing the buffer layer onto the GaAs substrate was relieved by a periodic array of the 901 misfit dislocations with the Burgers vector of 1/2a /1 1 0S for the thin AlSb islands buffer, but by both 601 and 901 misfit dislocations for the thick rough-and-flat AlSb buffer. The 901-misfit dislocation array of AlSb/GaAs interface had an average spacing of 4.80 nm. The mean roughness of the GaSb film on the thin AlSb islands buffer layer was found to be less than 1 nm. These results clearly demonstrate that the presence of a thin, LT AlSb islands initiation layer is very useful for improving the quality of GaSb crystals grown on GaAs substrates.
Interface structure of deposited GaSb on GaAs (001): Monte Carlo simulation and experimental study
Journal of Materials Science, 2011
The growth of GaSb thin films by MBE on GaAs (001) is investigated experimentally, using TEM, and theoretically, using KMC simulations. The atomic scale mechanisms inherent to the growth are discussed and described in the KMC model in which the strain is introduced through an elastic energy term based on a valence force field approximation. We observe that the first two monolayers of the deposited films form strained three-dimensional clusters, but further deposition induces film relaxation and rough 3D growth with valley formation presenting (111) facets with unstable bottoms. We show that the roughening morphology and creation of grooves during growth are in agreement with experimental TEM observations.
Molecular beam epitaxial growth of GaSb/GaAs quantum dots on Ge substrates
Journal of Crystal Growth, 2014
We perform structural and optical investigations of GaSb/GaAs quantum dots (QDs) grown on Ge (001) substrates by molecular beam epitaxy. Anti-phase domains (APDs) of GaAs are distributed on Ge substrate after the growth of GaAs due to the growth nature of III-V compound on group IV semiconductors having polar and non-polar behaviors. The APDs affect the QD growth as demonstrated by the growth of conventional InAs QDs on this surface. For GaSb QDs, the GaSb layer is grown on GaAs APD surface and compared with the GaSb layer on conventional (001) GaAs surface. Self-assembled QDs are formed on both surfaces but structural analysis reveals evidence of shape and size differences, which is attributed to the influence of the initial surface. Photoluminescence of GaSb/GaAs QDs grown on both Ge and GaAs substrates is studied. Emission from GaSb/GaAs QDs on Ge substrate can be detected till near room temperature (270 K).
Japanese Journal of Applied Physics, 2013
Growth of 90° interfacial-misfit-dislocation (IMF) array at heterointerfaces offers low dislocation densities in highly mismatched heterostructures such as GaSb/GaAs. We investigated time-integrated and time-resolved photoluminescence (PL) properties of a GaSb/AlGaSb quantum well (QW) structure grown on (001) GaAs substrate with and without IMF array at the GaSb-buffer/GaAs interface. Our observation reveals that the low-temperature PL from the QW with IMF is twice more intense than that of the QW without IMF, indicating higher quantum efficiency with IMF. The QW with IMF also exhibited the band filling effect at higher excitation power revealed from the spectrally resolved PL decay measurements. These results are the indication of subdued dislocation density with the IMF growth mode. Our PL measurement results along with supportive band-structure calculation of the GaSb/AlGaSb QW show that the luminescence efficiency of the present QW structure is limited by the hole leakage at ele...