Tem Studies of GaAs/AlGaAs Heterostructures Grown on Patterned Substrates

1987 ◽  
Vol 102 ◽  
Author(s):  
D. M. Hwang ◽  
E. Kapon ◽  
M. C. Tamargo ◽  
J. P. Harbison ◽  
R. Bhat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Chemical Etching ◽  
Molecular Beam ◽  
Patterned Substrates ◽  
Lateral Direction ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Device Applications ◽  
Substrate Surfaces

ABSTRACTEpitaxical growth rates depend strongly on the crystalline orientations of substrate surfaces. Multilayer growth on pre-patterned substrates with various crystal facets exposed results in a large variation of layer thicknesses in the lateral direction. This lateral definition can be used in device applications. Alternating layers of GaAs and AIGaAs were grown by molecular beam epitaxy on (100) GaAs substrates patterned with grooves and ridges along the [01T] and [011] directions by chemical etching. The results were analyzed with transmission electron microscopy using vertical cross-section techniques. Examples of using this method to fabricate ridges with tips of atomic sharpness and quantum-well lasers are presented.

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.

Threading Dislocations in InxGabxAs/GaAs System

1991 ◽  
Vol 240 ◽  
Author(s):  
M. Tamura ◽  
A. Hashimoto ◽  
Y. Nakatsugawa
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Cross Section ◽  
Molecular Beam ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Edge Type ◽  
Transmission Electron ◽  
Fixed Film

ABSTRACTThreading dislocation morphologies and characters, as well as their generation conditions in InxGa1−xAs films grown by molecular-beam epitaxy on GaAs (001) substrates have been examined, mainly using cross-section al transmission electron microscopy (XTEM) as a function of x and film thickness. The formation of severe threading dislocations is detected in epilayers ofx≧0.2 at a fixed film thickness of 3 μm and with film thicknesses greater than 2μmat x=0.2. Most of the observed threading dislocations are 60°- and pure-edge type dislocations along the <211> and [001] directions, respectively. The former type dislocations are mainly observed in layers of x≧0.2; the latter predominantly exist in layers of X≧O.3.

A transmission electron microscopy investigation of SiC films grown on SiC substrates by solid-source molecular beam epitaxy

1999 ◽  
Vol 14 (8) ◽  
pp. 3226-3236 ◽  
Author(s):  
U. Kaiser ◽  
I. Khodos ◽  
P. D. Brown ◽  
A. Chuvilin ◽  
M. Albrecht ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Substrate Surfaces ◽  
Step Flow Growth ◽  
Sic Films

The relationship between the defect microstructure of SiC films grown by solid-source molecular-beam epitaxy on 4H and 6H–SiC substrates and their growth conditions, for substrate temperatures ranging between 950 and 1300 °C, has been investigated by a combination of transmission electron microscopy and atomic force microscopy. The results demonstrate that the formation of defective cubic films is generally found to occur at temperatures below 1000 °C. At temperatures above 1000 °C our investigations prove that simultaneous supply of C and Si in the step-flow growth mode on vicinal 4H and 6H substrate surfaces results in defect-free hexagonal SiC layers, and defect-free cubic SiC can be grown by the alternating deposition technique. The controlled overgrowth of hexagonal on top of cubic layers is demonstrated for thin layer thicknesses.

Dopant Analysis on Advanced CMOS Technologies

2008 ◽  
Author(s):  
Frank Siegelin ◽  
Anja Dübotzky ◽  
Bodo Danzfuss ◽  
Stephan Schömann
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Chemical Etching ◽  
Semiconductor Devices ◽  
Spreading Resistance ◽  
Transmission Electron ◽  
Top View

Abstract This paper gives an overview of methods for imaging the distributions of dopant in semiconductor devices. Top view imaging by means of NanoSIMS and chemical etching will be discussed as well as cross section imaging on etched transmission electron microscopy (TEM) lamellas and Scanning Spreading Resistance Microscopy (SSRM).

A study of ordered domains in Ga0.5In0.5P Grown by MOVPE

1993 ◽  
Vol 51 ◽  
pp. 812-813
Author(s):  
Jane G. Zhu ◽  
D. J. Friedman ◽  
M. M. Al-Jassim ◽  
J. M. Olson
Keyword(s):  
Electron Microscopy ◽  
Chemical Etching ◽  
Atomic Ordering ◽  
Plan View ◽  
Substrate Orientation ◽  
The Past ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Ordered Alloys ◽  
Lattice Matched

Atomic ordering in III-V alloys is known to influence the physical properties of these materials. Therefore, the understanding and the control of the formation of ordered alloys are very important. Ordering in Ga0.5In0.5P, which is lattice matched to GaAs, occurs on two out of four {111} planes, i.e., . The substrate orientation can affect the selection between the two ordered variants. Studies on atomic ordering in III-V alloys have been carried out during the past several years.Transmission electron microscopy (TEM) and selected-area diffraction have been used in this study to investigate the ordered domains in Ga0.5In0.5P layers. The samples were grown on misoriented (100) GaAs substrates, mostly 2° towards [001] unless otherwise specified, by metalorganic vapor phase epitaxy at 670°C with a growth rate ∼5 μm/hr. The layer thicknesses range from 1.5 to 12 μm. Plan-view specimens were prepared by chemical etching from the substrate sides and examined using a Philips CM30 microscope operated at 300 kV.

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.

Atomic Structure of HgTe and CdTe Epitaxial Layers Grown by MBE on GaAs Substrates

1986 ◽  
Vol 90 ◽  
Author(s):  
F. A. Ponce ◽  
G. B. Anderson ◽  
J. M. Ballingall
Keyword(s):  
Electron Microscopy ◽  
Atomic Structure ◽  
Molecular Beam ◽  
Atomic Level ◽  
Point Of View ◽  
Defect Structures ◽  
Mbe Growth ◽  
Molecular Beam Epitaxial ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTUsing high resolution transmission electron microscopy (HRTEM) it is possible to directly image the projected structure of semiconductors with point resolutions at the atomic level. This technique has been applied to the study of interface and defect structures associated with molecular beam epitaxial (MBE) growth of HgCdTe layers on GaAs substrates. The structure of the CdTe/GaAs interfaces is described for (100) and (111) epitaxy. From the atomic structure, a model for the early stages of epitaxial growth is presented. The structure of HgTe-CdTe superlattices is discussed from the HRTEM point of view.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

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