The Structure of Dislocations in GaN Grown by MBE as a Function of the Gallium to Nitrogen Ratio

2003 ◽  
Vol 798 ◽  
Author(s):  
Marcus Q. Baines ◽  
David Cherns ◽  
Sergei V. Novikov ◽  
Michael J. Manfra ◽  
C. Thomas Foxon
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Fundamental Property ◽  
Growth Surface ◽  
Force Microscopy ◽  
The Core ◽  
Weak Beam ◽  
Atomic Force ◽  
Transmission Electron ◽  
Nitrogen Ratio

ABSTRACTTransmission electron microscopy (TEM) and atomic force microscopy (AFM) have been used to analyse the core structure of dislocations in GaN grown by molecular beam epitaxy (MBE) as a function of the gallium to nitrogen ratio. Ga-rich samples had a much smoother morphology; TEM observations showed that amorphous deposits decorated some dislocations and occasional surface pits, but weak beam and end-on imaging suggested that, away from the growth surface, dislocations of all types had closed core structures, in contrast to previous observations (Hsu et al, Appl. Phys. Lett. 78, 3980 (2001), Baines et al, Mat. Res. Soc. Symp. Proc. 743, L2.5 (2003)). Ga-poor samples were found to have much rougher surfaces; dislocations were often at the centers of deep surface pits but were observed to be undecorated and to have closed core structures. It is concluded that in growth under Ga-rich conditions, decoration of dislocation cores depends on the accumulation of Ga at surface pits, rather than being a fundamental property of dislocation formation.

TEM Studies on the Microstructure of m-Face Grown 4H-SiC by Solution Growth

2020 ◽  
Vol 1004 ◽  
pp. 414-420
Author(s):  
Junro Takahashi ◽  
Kotaro Kawaguchi ◽  
Kazuhiko Kusunoki ◽  
Tomoyuki Ueyama ◽  
Kazuhito Kamei
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solution Growth ◽  
Spiral Growth ◽  
Growth Surface ◽  
Vicinal Surface ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

We have studied the microstructure of the growth surface of the 4H-SiC grown by the m-face solution growth. Atomic Force Microscopy (AFM) revealed the micro-striped morphology with the asperity of several nm in the band-like morphology region. The cross-sectional Transmission Electron Microscopy (XTEM) showed that the growth surface consisted of a bunch of nanofacets and vicinal surface. This peculiar morphology is totally different from that of conventional spiral growth on c-face, which can be closely related with the growth mechanism of the m-face solution growth.

A transmission electron microscopy investigation of SiC films grown on Si(111) substrates by solid-source molecular beam epitaxy

1998 ◽  
Vol 13 (12) ◽  
pp. 3571-3579 ◽  
Author(s):  
U. Kaiser ◽  
S. B. Newcomb ◽  
W. M. Stobbs ◽  
M. Adamik ◽  
A. Fissel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Growth Parameters ◽  
Force Microscopy ◽  
Molecular Beam Epitaxial ◽  
Atomic Force ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Sic Films

The effects of different growth parameters on the microstructure of the SiC films formed during simultaneous two-source molecular-beam-epitaxial (MBE) deposition have been investigated. Substrate temperatures as low as 750–900 °C have been used. The relationship between a number of different growth morphologies and deposition conditions has been established. The formation of single-crystal 3C films has been found to occur at low growth rates but within a limited Si: C adatom ratio. A combination of transmission electron microscopy (TEM) and atomic force microscopy (AFM) has been used to examine the different films, and the results of these investigations are described.

Ordering of InGaAs Quantum Dots Grown by Molecular Beam Epitaxy under As2 gas flux

2015 ◽  
Vol 1792 ◽  
Author(s):  
Mourad Benamara ◽  
Yuriy I. Mazur ◽  
Peter Lytvyn ◽  
Morgan E. Ware ◽  
Vitaliy Dorogan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Atomic Force Microscopy ◽  
Molecular Beam Epitaxy ◽  
Large Scale ◽  
Molecular Beam ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTThe influence of the substrate temperature on the morphology and ordering of InGaAs quantum dots (QD), grown on GaAs (001) wafers by Molecular Beam Epitaxy (MBE) under As2 flux has been studied using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Photoluminescence (PL) measurements. The experimental results show that lateral and vertical orderings occur for temperatures greater than 520°C and that QDs self-organize in a 6-fold symmetry network on (001) surface for T=555°C. Vertical orderings of asymmetric QDs, along directions a few degrees off [001], are observed on a large scale and their formation is discussed.

Dislocation reduction with quantum dots in GaN grown on sapphire substrates by molecular beam epitaxy

2002 ◽  
Vol 722 ◽  
Author(s):  
David J. Smith ◽  
Daming Huang ◽  
Michael A Reshchikov ◽  
Feng Yun ◽  
T. King ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Aln Buffer

AbstractWe have investigated a novel approach for improving GaN crystal quality by utilizing a stack of quantum dots (QDs) in GaN grown on sapphire substrates by molecular beam epitaxy. The GaN films were grown on GaN/AlN buffer layers containing multiple QDs and characterized using x-ray diffraction, photoluminescence, atomic force microscopy, and transmission electron microscopy. The density of the dislocations in the films was determined by defect delineation wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN QD layers in the buffer layer effectively reduced the density of the dislocations in the epitaxial layers. As compared to a density of ∼1010cm-2in typical GaN films grown on AlN buffer layers, a density of ∼3×107cm-2was demonstrated in GaN films grown with the QD layers. Transmission electron microscopy observations confirmed termination of threading dislocations by the QD layers.

scholarly journals Nominal PbSe nano-islands on PbTe: grown by MBE, analyzed by AFM and TEM

2004 ◽  
Vol 829 ◽  
Author(s):  
Peter Moeck ◽  
Mukes Kapilashrami ◽  
Arvind Rao ◽  
Kirill Aldushin ◽  
Jeahuck Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Probe Microscopy ◽  
Strain State ◽  
Molecular Beam ◽  
Scanning Probe ◽  
Crystallographic Structure ◽  
Number Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTNominal PbSe nano-islands were grown in the Stranski-Krastanow mode on (111) oriented PbTe/BaF2 pseudo-substrates by molecular beam epitaxy (MBE). The number density and morphology of these islands were assessed by means of atomic force microscopy (AFM). Transmission electron microscopy (TEM) was employed to determine the strain state and crystallographic structure of these islands. On the basis of both AFM and TEM analyses, we distinguish between different groups of tensibly strained islands. The suggestion is made to use such nano-islands as part of nanometrology standards for scanning probe microscopy.

Slipline Offset of In.25Ga.75As/GaAs (100) Imaged by Atomic Force Microscopy

1993 ◽  
Vol 308 ◽  
Author(s):  
S.E. Harvey ◽  
J.E. Angelo ◽  
W.W. Gerberich
Keyword(s):  
Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Surface Instability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
The Difference ◽  
Scanning Electron

ABSTRACTWe have discovered a surface instability in In.25GaAs.75/GaAs (100) grown by molecular beam epitaxy (MBE) by direct comparison of atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigations. While slipline spacings measured by AFM correspond fairly well with those measured by TEM and SEM, the height displacement measured by AFM was seven times greater than that inferred from dislocations observed with TEM; the number of dislocations are insufficient to produce such dramatic heights. The difference in height measured by AFM with respect to the theoretical height calculated by strain relaxation and TEM dislocation number measurement can be attributed to a surface instability.

Investigation of the Shape of InGaAs/GaAs Quantum Dots

2002 ◽  
Vol 737 ◽  
Author(s):  
Susan Y. Lehman ◽  
Alexana Roshko ◽  
Richard P. Mirin ◽  
John E. Bonevich
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Molecular Beam ◽  
Length Scale ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Three Samples

ABSTRACTThree samples of self-assembled In0.44Ga0.56As quantum dots (QDs) grown on (001) GaAs by molecular beam epitaxy (MBE) were studied using atomic force microscopy (AFM) and high-resolution transmission electron microscopy (TEM) in order to characterize the height, faceting, and densities of the QDs. The cross-sectional TEM images show both pyramidal dots and dots with multiple side facets. Multiple faceting has been observed only in dots more than 8.5 nm in height and allows increased dot volume without a substantial increase in base area. Addition of a GaAs capping layer is found to increase the diameter of the QDs from roughly 40 nm to as much as 200 nm. The areal QD density is found to vary up to 50 % over the central 2 cm x 2 cm section of wafer and by as much as 23 % on a length scale of micrometers.

Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 215
Author(s):  
Rajeev R. Kosireddy ◽  
Stephen T. Schaefer ◽  
Marko S. Milosavljevic ◽  
Shane R. Johnson
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Interface Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Lateral Variations

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

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