Molecular beam epitaxial growth and characterization of zinc-blende ZnMgSe on InP (001) (original) (raw)
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Journal of Vacuum Science & Technology B, 2005
Lattice matched ZnMgSe grown on InP is of considerable interest for its potential applications as a cladding layer due to the high band-gap energy ͑ϳ3.6 eV͒ and for use in intersubband devices such as quantum cascade lasers. Several lattice matched Zn 0.5 Cd 0.5 Se/ Zn 0.13 Mg 0.87 Se quantum wells ͑QWs͒ were grown on InP ͑001͒ substrates. Emission ranging from the near UV to the visible spectral range was achieved by varying the thickness of the wells. The QW fundamental transition as function of the QW thickness was experimentally studied and modeled using an envelope calculation. The contactless electroreflectance measurements of a Zn 0.5 Cd 0.5 Se/ Zn 0.13 Mg 0.87 Se single QW yielded multiple transitions from the QW, allowing us to estimate the conduction band offset of this heterostructure to be as high as 1.12 eV.
Metalorganic vapor-phase epitaxy of ZnMgCdSe structures on InP
Journal of Crystal Growth, 2000
Metalorganic vapor-phase epitaxy of ternary ZnMgSe layers and, for the "rst time, quaternary ZnMgCdSe superlattices is presented. Lattice-matched Zn Mg Se with a high magnesium content x and a good structural quality was achieved by introducing a lattice-matched ZnCdSe bu!er and phosphorus stabilisation during InP deoxidation. We obtained a rocking curve half-width below 100 arcsec for a 300 nm thick layer with x"0.86. Lattice matching on InP was achieved for ZnMgCdSe layers with magnesium concentrations from 38% to 68%, corresponding to a bandgap of 2.9 and 3.4 eV, respectively. An overall optical gain of 35 cm\ was observed in a ZnMgCdSe superlattice structure. 2000 Elsevier Science B.V. All rights reserved.
ZnMgCdSe structures on InP grown by MOVPE
Journal of Crystal Growth, 2000
Metalorganic vapor-phase epitaxy of ternary ZnMgSe and ZnCdSe layers, quaternary ZnMgCdSe layers and superlattices on InP (1 0 0) is presented. The dependence of the Cd-and Mg-incorporation into the ternary compounds on the molar ratio in the vapor phase, and the in#uence of the bu!er material and the growth conditions on the structural quality are discussed. A tendency to segregation and increased mosaicity is found in quaternary ZnMgCdSe structures with magnesium fractions exceeding 40%, evaluated by X-ray di!raction, photoluminescence and transmission electron microscopy.
Low pressure MOVPE growth and structural properties of ZnMgSe epilayers on (100)GaAs
Journal of Crystal Growth, 2000
The low-pressure MOVPE growth of ZnMgSe on (1 0 0)GaAs is reported. ZnMgSe alloys were deposited after a thin pseudomorphic ZnSe bu!er layer by using dimethylzinc : triethylammine (Me Zn : Et N), ditertiarylbutilselenide (Bu Se) and bis(methylcyclopentadienyl)magnesium [(MeCp) Mg]. Zn \V Mg V Se (0.10(x(0.46) epilayers were grown at 3303C, 304 mbar and a high VI/II ratio in the vapour. Under these conditions the growth is limited by the mass transport of the II-group alkyls and good control of the composition was achieved. Rutherford backscattering spectrometry measurements allowed to determine the epilayer stoichiometry and deposited dose. The ZnMgSe solid}vapour distribution curve deviates from linearity due to the di!erent Mg and Zn alkyl vapour di!usion coe$cients, whose ratio turns out to be D + ! + /D + 8 "0.410. The epilayer crystalline properties were studied by double-crystal X-ray di!raction (DC-XRD) and high-resolution reciprocal space mapping (RSM) measurements. Rocking curve FWHM values of 540}900 nm thick Zn \V Mg V Se were in the 5}12 mrad range, indicating the occurrence of extended defects in the epilayers. RSM measurements in the vicinity of the (400)-peak of a Zn Mg Se/ZnSe/(1 0 0)GaAs sample showed a slight asymmetry of the ternary alloy peak along the growth direction, ascribed to an inhomogeneous relaxation of the epilayer. (P. Prete). blue}green light emitting laser diodes (LDs), in the form of GaAs-matched ZnMgSSe cladding layers for photon con"nement or quantum well barriers for the LD active region . Interest in the ZnMgSe ternary alloy has raised, for it borders the ZnMgSSe compound and its study helps to determine the structural and electronic properties of the quaternary alloys. Also, ZnMgSe/ZnSe quantum wells have been studied for the realisation 0022-0248/00/$ -see front matter
Wide-band-gap ZnMgBeSe alloys grown onto GaAs by molecular beam epitaxy
Journal of Crystal Growth, 2001
We have investigated ZnMgBeSe-quaternary wide-band-gap alloys grown by molecular beam epitaxy lattice-matched or moderately strained onto (0 0 1)-GaAs substrates, paying attention to preserve conditions compatible with the growth of other ZnSe-based compounds. Two-dimensional growth is obtained up to band gaps as high as 3.5 eV, as measured by reflectivity. Intense and narrow photoluminescence is observed for all samples, up to 3.6 eV. X-ray linewidths as narrow as 10 arcsec are obtained which compare very well with the substrate value of 7 arcsec. This reveals the high crystal quality of the epitaxial material. Our results show that this material is well suited for UVA detection. #
MBE Growth and Characterization of MgS-Rich Zinc-Blende ZnxMg1-xS1-ySey Alloys
Journal of the Korean Physical Society, 2008
Samples containing ZnMgSSe alloy were grown by using molecular beam epitaxy at 240 • C and were analyzed by using X-ray interference. The alloy composition was found to be Zn0.20Mg0.80S0.64Se0.36. The surfaces of these layers were found to be extremely flat, unlike MgS layers of similar thickness grown under identical conditions, which show pronounced ridges. Structures with Zn0.20Mg0.80S0.64Se0.36 barriers were grown with ZnSe quantum wells and showed good quantum confinement with a sharp PL peak. Calculations of the phase stability of ZnMgSSe alloys suggest that an alloy of this composition should phase separate. However, samples with this composition are demonstrably single phase, and the discrepancy with the calculation can be removed if the enthalpy of formation of zinc-blende MgS is reduced by less than 2 % to −231 kJ mol −1 .
Energy band gaps of Zn1−xMgxSySe1−y lattice matched to GaAs
Physica B: Condensed Matter, 2003
We report on theoretical study of the energy band gaps for the quaternary alloys Zn 1Àx Mg x S y Se 1Ày in conditions of lattice matching to GaAs substrates using simply the empirical pseudopotential method under the virtual crystal approximation which takes into account the effects of compositional disorder. Our results agree generally very well with the available experimental data. It is shown that the band-gap energies of Zn 1Àx Mg x S y Se 1Ày are expressed by the parabolic function of the composition considering the bowing parameter and that Zn 1Àx Mg x S y Se 1Ày can be a direct or an indirect semiconductor depending on the alloy composition. The Zn 0:35 Mg 0:65 S 0:6 Se 0:4 is predicted to meet requirement of the cladding layer for fabricating blue double heterostructure laser diodes using ZnS 0:06 Se 0:94 as the active layer.
Optical properties of Zn0.5Cd0.5Se thin films grown on InP by molecular beam epitaxy
Solid State Communications, 2003
We report photoluminescence (PL) and reflectivity measurements of Zn 0.5 Cd 0.5 Se epilayers grown by molecular beam epitaxy on InP substrates. The low-temperature PL spectra are dominated by asymmetric lines, which can be deconvoluted into two Gaussian peaks with a separation of ,8 meV. The behavior of these peaks is studied as a function of excitation intensity and temperature, revealing that these are free exciton (FE) and bound exciton emission lines. Two lower energy emission lines are also observed and assigned to the first and second longitudinal optical phonon replicas of the FE emission. The temperature dependence of the intensity, line width, and energy of the dominant emission lines are described by an Arrhenius plot, a Bose-Einstein type relationship, Varshni's and Bose-Einstein equations, respectively.
Molecular beam epitaxy and optical properties of ZnCdS/ZnMgS quantum wells on GaP
Journal of Crystal Growth, 2000
We report the growth of ZnCdS/ZnMgS quantum wells (QWs) and their optical properties. The constituent alloy layers were grown by molecular beam epitaxy under a large S #ux and a high substrate temperature. The layers exhibit high quality in terms of double crystal X-ray rocking curve and optical spectra including photoluminescence (PL), PL excitation and re#ection spectra. The ZnCdS/ZnMgS QWs exhibit strong emission from the ZnCdS well(s) through photo-excitation at the ZnMgS barriers. By changing the growth condition of the QW structures, PL line width can be reduced. Such QWs show PL up to room temperature.