MBE growth and characterisation of AlxGa1−xSb layers on GaSb substrates (original) (raw)
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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
Secondary-ion-mass spectrometry and high-resolution x-ray diffraction are used to investigate Al x Ga 1Ϫx Sb/GaSb heterostructures (0.2ϽxϽ1) grown by molecular beam epitaxy. We show that the AlCs ϩ and GaCs ϩ intensities, obtained by using caesium cluster secondary-ion-mass spectrometry mode, vary linearly with the relative concentrations, and therefore, allows us to evaluate quantitatively the aluminum and gallium contents in the epitaxial layers. Intermixing of Ga/Al species at the GaSb/AlSb interfaces could be clearly detected by secondary-ion-mass spectrometry and is also confirmed by high-resolution x-ray diffraction. The intermixing is the result of a particular mechanism in order to minimize the strain energy, and occurs prior to the lattice relaxation, which generates structural defects taking place. The analyses also give evidence of a constant arsenic contamination ͑ϳ0.5%͒ both in the GaSb buffer and in the Al x Ga 1Ϫx Sb layers. In fact, As contamination occurs if the molecular beam epitaxy chamber has been used previously for the growth of As-compound materials. We show that the signal obtained by using the caesium cluster secondary-ion-mass spectrometry mode AsCs ϩ is nearly unaffected by the changes of the Al content throughout the total structure ͑matrix effects͒ contrary to what occurs for single As ions.
Liquid phase epitaxial growth of AlGaAsSb on GaSb
Journal of Crystal Growth, 1992
1_~As~Sb1_(x 0.37 and 0.47) alloy has been grown on GaSb substrate by liquid phase epitaxy from melts containing X'(Al) = 0.02 and 0.03. Satisfactory layers could be obtained at T°= 605°Cusing small supercooling (iT = I -4°C) and small As content in the melt (X t(As) = l0~~). The conditions of growing lattice-matched structures have been theoretically evaluated and experimentally determined. Growth kinetics obey the law: d = KziTt'~2,which is characteristic of a diffusion-limited growth, with K=0.054 jim°C' s"2 for (100) orientation and K=0.036~m0C~~_l/2 for the (111)B. Undoped layers are p-type with a residual carrier concentration p 1016 cm3. Photoluminescence measurements at 2 K show excitonic and phonon assisted lines, characteristic of good quality indirect gap material. High doping levels were achieved by Ge doping (p = 1019 cm3) and Te doping(n = 2x10'8 cm3).
Advances in Materials Science and Engineering, 2010
EpitaxialAlxGa1-xSb layers on GaAs substrate have been grown by atmospheric pressure metalorganic chemical vapour deposition using TMAl, TMGa, and TMSb. We report the effect of V/III flux ratio and growth temperature on growth rate, surface morphology, electrical properties, and composition analysis. A growth rate activation energy of 0.73 eV was found. For layers grown on GaAs at 580∘C and 600∘C with a V/III ratio of 3 a high quality surface morphology is typical, with a mirror-like surface and good composition control. It was found that a suitable growth temperature and V/III flux ratio was beneficial for producing good AlGaSb layers. Undoped AlGaSb grown at 580∘C with a V/III flux ratio of 3 at the rate of 3.5 μm/hour shows p-type conductivity with smooth surface morphology and its hole mobility and carrier concentration are equal to 237 cm2/V.s and 4.6 × 1017 cm-3, respectively, at 77 K. The net hole concentration of unintentionally doped AlGaSb was found to be significantly dec...
Opto-Electronics Review, 2011
The antimonide laser heterostructures growth technology using MBE epitaxy is currently well−developed, while MOVPE method is still being improved. It is known that the principal problem for MOVPE is the oxygen and carbon contamination of aluminium containing waveguides and claddings. The solution would be to apply a proper aluminium precursor. In this study we present the results of metal−organic epitaxy of In− and Al−containing layers and quantum well structures composing antimonide lasers devices. Special emphasis was put on the aluminium precursor and its relation to AlGaSb and AlGaAsSb materials properties. The crystalline quality of the layers grown with two different Al precursors was compared, very good structural quality films were obtained. The results suggested a substantial influence of precursors pre−reactions on the epitaxial process. The oxygen contamination was measured by SIMS, which confirmed its dependence on the precursor choice. We also optimised the GaSb substrate thermal treatment to deposit high quality GaSb homoepitaxial layers. Quater− nary InGaAsSb layers were obtained even within the predicted miscibility gap, when arsenic content reached high above 10% values. InGa(As)Sb/AlGa(As)Sb quantum wells were grown and their optical properties were characterised by photoluminescence and photoreflectance spectroscopy. Type−I quantum wells showed a fundamental optical transition in the 1.9-2.1 μm range at room temperature. The epitaxial technology of the structures was subjected to an optimisation proce− dure. The investigated layers and heterostructures can be considered for application in laser devices.
Characterization of Al0.047Ga0.953Sb layers grown on GaSb using reciprocal space maps
Materials Letters, 2016
Structures of Al 0.047 Ga 0.953 Sb layers on GaSb (100) substrates were studied by high resolution X-ray diffraction (HRXRD) using reciprocal space maps (RSM) and rocking curves around the (004) and (115) reflections. The layers were grown at 450°C with a supersaturation of 10°C in a conventional Liquid Phase Epitaxy (LPE) system varying the growth time from 1 to 4 min resulting in an increment of thickness. It was found that tilt, relaxation and dislocation density of the layers can be calculated using its rocking curves and reciprocal space mapping and it is found that these characteristics are influenced by the thickness of layer.
Study of optical and electrical properties of GaSb/Al/sub x/Ga/sub 1-x/Sb grown by MOCVD
2000 International Semiconducting and Insulating Materials Conference. SIMC-XI (Cat. No.00CH37046), 2000
We report the metalorganic chemical vapour deposition (MOCVD) growth conditions and properties of GaSb and AI,Gal.,Sb in the regime d. 2 5 , including the effect of VmI ratio and growth temperature on electrical and optical properties. GaSb and AhGal.$b compound layers were grown on GaAs substrate using TMAI, TMGa and TMSb precursors. Growth temperatures in the range of 520°C to 680°C and V/III ratios between 1 to 5 have been investigated.
Optical characterization of AlxGa1-xSb/GaSb epitaxial layers
Spectroscopic ellipsometry from 1.4 to 5 eV was used to systematically characterize epitaxial heterostructures AlxGa1-xSb/GaSb for different x concentrations (x ≤ 0.5). The structures were grown by MBE at temperatures and beam equivalent pressure ratios which optimize their low-temperature photoluminescence properties. Complex dielectric functions ε(ω) of AlxGa1-xSb versus x were derived, for the first time, from the ellipsometric spectra after mathematically removing the oxide overlayer effects. The ε(ω) spectra were analyzed with their second energy-derivatives in term of standard analytical lineshapes in particular the E1, E1 + Δ1 and E2 critical point energies, broadening and amplitude parameters were derived as a function of x. On this basis we verified that the energy-shift model is appropriate to interpolate ε(ω) for any x ≤ 0.5, thus allowing a nondestructive optical diagnostic of layer thickness and composition of epitaxial heterostructures based on AlxGa1-xSb.
Structural characterization of AlxGa1−xSb grown by LPE
Materials Science in Semiconductor Processing, 2012
Al x Ga 1 À x Sb ternary solid solutions lattice-matched to the GaSb (001) substrate with composition in the range 0.05 r x r 0.2 were grown by liquid phase epitaxy. High resolution X-ray diffraction and Raman scattering techniques were applied to characterize Al x Ga 1 À x Sb alloys. The out of plane lattice parameter was estimated directly from the asymmetrical diffractions of planes (115) and (À 1 À 15). The out of plane lattice parameter as a function of Aluminium content is higher than the corresponding bulk lattice parameter of Al x Ga 1 À x Sb layers obtained with Vegard's law. These results show that some of the layers are more strained than others. Two peaks are observed in their Raman spectra over this composition range. The assignment of the observed modes to GaSb-like modes is discussed. The studies of the chemical composition of the layers by SIMS exhibit the presence of tellurium, carbon and oxygen like the main residual impurities.