Structural Characterization of Composition-Modulated ZnSel-xTex Epitaxial Films

1995 ◽  
Vol 417 ◽  
Author(s):  
S. P. Ahrenkiel ◽  
M. H. Bode ◽  
M. M. Al-Jassim ◽  
H. Luo ◽  
S. H. Xin ◽  
...  
Keyword(s):  
Cross Sections ◽  
Small Amplitude ◽  
Molecular Beam ◽  
Growth Direction ◽  
Epitaxial Films ◽  
Modulation Amplitude ◽  
Transmission Electron ◽  
Short Period ◽  
Strain Modulation

AbstractWe examine the microstructure of short-period (14–31 Å) composition modulations in epitaxial ZnSel-xTex ([email protected]) films grown by molecular-beam epitaxy (MBE) on vicinal (001) GaAs. Transmission electron microscope (TEM) images of cross-sections reveal highly-periodic contrast along the growth direction throughout the full thicknesses of the films (over 2 μm) that corresponds to a nearly sinusoidal variation between Se- and Te-rich compositions. Growth of ZnSe1-xTex at 285°C on substrates tilted 4° toward [1111 maximizes the strength and regularity of the modulation. Using dynamical electron-diffraction simulations, we estimate a modulation amplitude of [email protected](7) in a sample showing strong modulation. We assume a small amplitude of strain modulation to fit the experimental data.

An Electron Microscopic Characterization of Mbe-Grown ZnSe/CaAs and ZnSe/Ge Heterointerfaces

1990 ◽  
Vol 198 ◽  
Author(s):  
S.B. Sant ◽  
R.W. Smith ◽  
G.C. Weatherly
Keyword(s):  
Molecular Beam ◽  
Nucleation And Growth ◽  
Epitaxial Films ◽  
Defect Characterization ◽  
Initial Growth ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTMolecular beam epitaxy (MBE) grown ZnSe/GaAs and ZnSe/Ge heterointerfaces have been studied by transmission electron microscopy (TEM). Defect characterization of cross-sectional and planar specimens showed that ZnSe epitaxial films contain numerous twins that predominantly arise at the interface. Planar specimens of ZnSe/Ge were in-situ TEM annealed, for 5.5 hours at 873K. The twins are thermally very stable which would indicate that they arise during the growth process. The occurrence of these twins in the ZnSe film is explained by nucleation and growth of normal and twinned nuclei. Some of the ZnSe films grown on (10O)Ge substrates have low-angle boundaries indicating that the initial growth of the film is by the formation of islands.

Growth and characterization of In2Se3 epitaxial films by molecular beam epitaxy

1997 ◽  
Vol 175-176 ◽  
pp. 1045-1050 ◽  
Author(s):  
Tamotsu Okamoto ◽  
Akira Yamada ◽  
Makoto Konagai
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Epitaxial Films

Epitaxial Growth and Characterization of the Ordered Vacancy Compound CuIn3Se5 on GaAs (100) Fabricated by Molecular Beam Epitaxy

1994 ◽  
Vol 340 ◽  
Author(s):  
Art J. Nelson ◽  
M. Bode ◽  
G. Horner ◽  
K. Sinha ◽  
John Moreland
Keyword(s):  
Molecular Beam Epitaxy ◽  
Epitaxial Growth ◽  
Molecular Beam ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
Symmetric Vibration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTEpitaxial growth of the ordered vacancy compound (OVC) CuIn3Se5 has been achieved on GaAs (100) by molecular beam epitaxy (MBE) from Cu2Se and In2Se3 sources. Electron probe microanalysis and X-ray diffraction have confirmed the composition for the 1-3-5 OVC phase and that the film is single crystal Culn3Se5 (100). Transmission electron microscopy (TEM) characterization of the material also showed it to be single crystalline. Structural defects in the layer consisted mainly of stacking faults. Photoluminescence (PL) measurements performed at 7.5 K indicate that the bandgap is 1.28 eV. Raman spectra reveal a strong polarized peak at 152 cm−1, which is believed to arise from the totally symmetric vibration of the Se atoms in the lattice. Atomic force microscopy reveals faceting in a preferred (100) orientation.

Structural properties of molecular beam epitaxy grown Ni/Pt superlattices

1997 ◽  
Vol 12 (1) ◽  
pp. 161-174 ◽  
Author(s):  
W. Staiger ◽  
A. Michel ◽  
V. Pierron-Bohnes ◽  
N. Hermann ◽  
M. C. Cadeville
Keyword(s):  
Molecular Beam ◽  
Growth Direction ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Plan View ◽  
X Ray ◽  
Transmission Electron ◽  
Superlattice Peak ◽  
Diffraction Peaks ◽  
Diffraction Patterns

We find that the [Ni3.2nmPt1.6nm] × 15 and [Ni3.2nmPt0.8nm] × 15 multilayers are semicoherent and display a columnar morphology. From both the period of the moir’e fringes and the positions of the diffraction peaks in electronic (plan-view and crosssection geometries) and x-ray diffraction patterns, one deduces that the nickel is relaxed (at least in the error bars of all our measurements), whereas the platinum remains slightly strained (≈−1%). The interfaces are sharp; no intermixing takes place giving rise to neat contrasts in transmission electron microscopy (TEM) and to high intensities of the superlattice peaks in the growth direction in both diffraction techniques. The relaxation of the interfacial misfit occurs partially through misfit dislocations, partially through the strain of platinum. A quasiperiodic twinning occurs at the interfaces, the stacking fault which forms the twin being the most often located at the interface Pt/Ni, i.e., when a Pt layer begins to grow on the Ni layer. The simulation of the θ/2θ superlattice peak intensities takes into account the columnar microstructure. It shows that the roughness is predominantly at medium scale with a fluctuation of about 12.5% for Ni layers and negligible for Pt layers.

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.

Effects of substrates and catalysts compositions on the crystalline quality of InP Nanowires grown on SrTiO3 (001), Si(001) and InP (111)

2010 ◽  
Vol 1258 ◽  
Author(s):  
Khalid Naji ◽  
Herve Dumont ◽  
Guillaume Saint-Girons ◽  
Gilles Patriarche ◽  
michel Gendry
Keyword(s):  
Molecular Beam ◽  
Defect Formation ◽  
High Energy ◽  
Growth Direction ◽  
Crystalline Quality ◽  
Metal Catalyst ◽  
Cubic Phase ◽  
High Energy Electron ◽  
Transmission Electron

AbstractIndium phosphide (InP) nanowires (NWs) were grown by molecular beam epitaxy on various substrates including SrTiO3 (001), Si (001) and InP (111) at a growth temperature of 380°C. We used the Vapor Liquid Solid assisted method with Au as a metal catalyst. The composition of the catalyst particles and the crystalline structure of the nanowires were compared using reflection high energy electron diffraction, scanning electron microscopy and high resolution transmission electron microscope. It is found that InP nanowires grown onto InP and SrTiO3 substrates are structurally defects free with a wurtzite structure. On Si (001) substrates, the presence of stacking faults and cubic phase insertion along the growth direction is observed. The effect of the substrate on the composition of catalyst droplets and consequently on the crystalline quality of the nanowires is discussed for the conditions of nucleation and defect formation.

scholarly journals Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction

2017 ◽  
Vol 24 (5) ◽  
pp. 981-990 ◽  
Author(s):  
Arman Davtyan ◽  
Sebastian Lehmann ◽  
Dominik Kriegner ◽  
Reza R. Zamani ◽  
Kimberly A. Dick ◽  
...  
Keyword(s):  
Bragg Peak ◽  
Stacking Faults ◽  
Growth Direction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Patterson Function ◽  
Transmission Electron ◽  
Gaas Nanowires ◽  
Gaas Nanowire

Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [000\bar{1}] direction in the vicinity of the wurtzite 00\bar{1}\bar{5} Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire.

Characterization of zinc diffusion induced disordering in GaAs/AlGaAs multiquantum well structures by Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 734-735
Author(s):  
B. Bourqui ◽  
P. A. Buffat ◽  
J.D. Ganière ◽  
F. K. Reinhart
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Multilayered Structures ◽  
Transmission Electron ◽  
Zinc Diffusion ◽  
Secondary Ion ◽  
Diffusion Of Impurities ◽  
Multiquantum Well

Diffusion of impurities, such as zinc or silicon, enhances the intermixing of Ga-Al atoms at GaAs/AlGaAs interfaces. This process is useful to modify the bandedge properties of multilayered structures such as (AlxGa1-xAs/GaAs). Important technological applications are due to this effect. Information about electronic states of the disordered structure is directly obtained by photoluminescence. The impurity induced disordering depth is, usually, estimated either by scanning electron microscopy (SEM) or by secondary ion mass spectroscopy (SIMS). We used transmission electron microscopy on wedge shaped specimen (WTEM) is used to obtain local information on the disordering depth and to check the chemical homogeneities of the diffused samples.The multiquantum well structures (MQW) were grown by molecular beam epitaxy (MBE) on n doped [001] substrate at surface temperature of 600 °C. A specimen structure is given in Figure 1. Zinc diffusions were performed by using the sealed quartz tube method at 575°C. The ZnAs2 source provide sufficient partial pressure of arsine to maintain the surface at equilibrium.

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