Structural Studies Of (ZnSe/FeSe) Superlattices By Transmission Electron Microscopy

1991 ◽  
Vol 238 ◽  
Author(s):  
K. Park ◽  
L. Salamanca-Riba ◽  
B. T. Jonker
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Misfit Strain ◽  
Structural Studies ◽  
Ordered Structure ◽  
Chemical Ordering ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTThe structural properties of (ZnSe/FeSe) superlattices, grown with and without a ZnSe buffer layer on (001) G a As substrates by molecular beam epitaxy, have been studied by transmission electron microscopy. High quality (ZnSe/FeSe) superlattices are obtained when grown on a ZnSe buffer layer on (001) GaAs substrates. In contrast, nominal (ZnSe/FeSe) superlattices grown directly on (001) GaAs substrates without a buffer layer showed evidence for intermixing of the layers in the superlattice indicating that the superlattice is unstable. We observed a disordered structure and an ordered structure in the resulting Zn1−xFexSe solid solution. The ordered structure corresponds to chemical ordering of Zn and Fe atoms along the < 100 > and < 110 > directions. We have studied the effect of misfit strain in the (ZnSe/FeSe) superlattices on the film quality.

Layer Tilt and Relaxation in InGaAs/GaAs Graded Buffer Layers

1995 ◽  
Vol 379 ◽  
Author(s):  
K.M. Matney ◽  
J.W. Eldredge ◽  
M.S. Goorsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
Cross Section ◽  
Mole Fraction ◽  
Molecular Beam ◽  
Reciprocal Space ◽  
Buffer Layers ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTWe investigated the effect of substrate inclination and direction on the structural properties of an InGaAs linearly compositionally graded buffer layer with a AlGaAs/InGaAs superlattice grown by molecular beam epitaxy on 2° offcut GaAs substrates. Reciprocal space maps were used to determine the relaxation and tilt of the buffer layer and superlattice with respect to each other and to the substrate. From (004) reciprocal space maps, a linear relationship between tilt and In mole fraction was observed for the buffer layer. This tilt was greatly reduced near the top of the buffer which was found to be completely strained. Interestingly, the tilt along a <110> direction was greater than that observed along the miscut axis. This may be due to the miscut axis not being parallel to a low index plane. Reciprocal space maps of asymmetric diffraction planes were used to determine the relaxation of the buffer layer as a function of In mole fraction. Along a <110> direction in which no tilt was seen in the (004), the majority of the buffer layer was found to be completely relaxed. However, the top of the buffer layer was found to be completely strained, corresponding to a denuded zone observed in cross section transmission electron microscopy.

Defects in Mbe-Grown GaAs/ScxEr1–xAs/GaAs Layers

1990 ◽  
Vol 198 ◽  
Author(s):  
Jane G. Zhu ◽  
Chris J. Palmstrdøm ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Growth Stage ◽  
Molecular Beam ◽  
Gaas Layer ◽  
Stacking Fault ◽  
Initial Growth ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTThe microstructure and the structure of defects in GaAs/ScxEr1–xAs/GaAs (x=0 and 0.3) heterostructures grown on (100) GaAs substrates by molecular beam epitaxy have been characterized using transmission electron microscopy. The top GaAs layer forms islands on ScxEr1–xAs at the initial growth stage, and the area covered by GaAs varies with the growth temperature. In addition to regions of epitactic (100) GaAs, regions of {122}- and (111)-oriented GaAs are observed on (100)-oriented ScxEr1–xAs. A high density of stacking-fault pyramids is found in epilayers of GaAs grown on a thin epilayer of ErAs, where the ErAs layers are only one or two monolayers thick. The apex of each stacking-fault pyramid is located at the ScxEr1–xAs/GaAs interface.

Tem Study of the Accidental Modulation of Mbe Grown AlxGal-x As

1986 ◽  
Vol 82 ◽  
Author(s):  
E.G. Britton ◽  
W.M. Stobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Long Range ◽  
Molecular Beam ◽  
Ordered Structure ◽  
Transmission Electron

ABSTRACTComposition modulations with a wavelength of -1-3 nm have been observed by transmission electron microscopy in nominally uniform AlxGa1-x As grown by molecular beam epitaxy. We describe the characterisation of this phenomenon and discuss its possible origins, in the light of the reported existence of a long range ordered structure.

Structural Characterization of Low-Temperature InN Buffer Layer Grown by RF-MBE

2003 ◽  
Vol 798 ◽  
Author(s):  
T. Araki ◽  
Y. Nanishi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Cubic Phase ◽  
Local Fluctuations ◽  
Transmission Electron ◽  
Surface Migration

ABSTRACTThe microstructure of an InN buffer layer grown on (0001) sapphire at low temperature by radio-frequency molecular beam epitaxy (RF-MBE) is characterized by transmission electron microscopy. The low-temperature InN buffer layer is found to contain local inhomogeneous regions of island-like grains surrounded by misoriented InN grains and inclusions of cubic phase. The generation of such anti-phase InN nuclei near the island-like grains is expected to give rise to defects at the interface. It is considered that these anti-phase InN nuclei are formed by local fluctuations of stoichiometry due to inadequate surface migration during the growth of the InN buffer layer, indicating the important of controlling the surface stoichiometry during InN growth.

A Tem study of Epitaxial FE/AG and MN/AG Superlattices

1989 ◽  
Vol 160 ◽  
Author(s):  
S. Nahm ◽  
L. Salamanca — Riba ◽  
B. T. Jonker ◽  
G. A. Prinz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
Seed Layer ◽  
Gaas Substrate ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Strain Modulation ◽  
Film Substrate ◽  
Sharp Interfaces

AbstractWe have studied the epitaxial growth and structural properities of single crystal Fe/Ag and Mn/Ag superlattices grown on (001) GaAs substrates using transmission electron microscopy. A buffer layer of Ag (001) was grown on a 5 monolayer Fe seed layer on the (001) GaAs substrate before the growth of the superlattice to obtain good quality films. For some samples an intermediate buffer layer of ZnSe was used, as well. Both Fe/Ag and Mn/Ag superlattices with a Ag buffer layer show very sharp interfaces. The densities of dislocations in the film and the buffer layer are the same suggesting that the dislocations originate at the film/substrate interface. We have observed evidence for a strain modulation of ≈ 8 Å in the Mn layer for thick (≈ 22 Å) Mn layers in the superlattice samples but not in samples with a thin Mn layer.

Vertical self-organization of Ge1−xMnx nanocolumn multilayers grown on Ge(001) substrates

2016 ◽  
Vol 30 (20) ◽  
pp. 1650269 ◽  
Author(s):  
Thi Giang Le ◽  
Minh Tuan Dau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Elastic Constant ◽  
Structural Properties ◽  
Molecular Beam ◽  
Self Organization ◽  
Transmission Electron ◽  
2D Model

High-resolution transmission electron microscopy (HR-TEM) has been used to investigate the structural properties of GeMn/Ge nanocolumns multilayer samples grown on Ge(001) substrates by means of molecular beam epitaxy (MBE) system. Four bilayers with the spacer thickness in the range between 6 nm and 15 nm and 10 periods of bilayers of Ge[Formula: see text]Mn[Formula: see text]/Ge nanocolumn are presented. A simplified 2D model based on the theory of elastic constant interactions has been used to provide reasonable explanations to the vertical self-organization of GeMn nanocolumns in multilayers.

Asymmetric Cracking in Znse/ZnSxSel−x Superlattices Grown by Molecular Bean Epitaxy

1987 ◽  
Vol 102 ◽  
Author(s):  
Richard J. Dalby ◽  
John Petruzzello
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Expansion ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Sulfur Concentration ◽  
Transmission Electron ◽  
Theoretical Predictions ◽  
Superlattice Layer

ABSTRACTOptical and transmission electron microscopy have been used to study cracks appearing in ZnSe/ZnSxSe1−x (x ∼ 0.38) superlattices grown by Molecular Beam Epitaxy. It Is shown that when a fracture occurs it is confined, in most cases, to the superlattice and propagates along <011> cleavage directions in these <001> oriented epilayers. Cracks were not observed in all superlattices and their onset is discussed in relation to sulfur concentration, overall superlattice height, individual superlattice layer thicknesses, and stress, tensile or compressive, due to lattice mismatch and thermal expansion differences between buffer layer and superlattice. It was found that by adjusting the controllable parameters, cracks in the superlattices could be eliminated. Orientation and density of these features have been related to asynnmetric cracking associated with the zincblende structure of these II-VI materials. Experimental results are shown to be in agreement with theoretical predictions of critical heights for the onset of cracking.

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