A Systematic Investigation of Strain Relaxation, Surface Morphology and Defects in Tensile and Compressive InGaAs/InP Layers

1999 ◽  
Vol 578 ◽  
Author(s):  
C. Ferrari ◽  
L. Lazzarini ◽  
G. Salviati ◽  
M. Natali ◽  
M. Berti ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Scanning Force Microscopy ◽  
Systematic Investigation ◽  
Misfit Dislocations ◽  
Extended Defects ◽  
Strained Layers ◽  
Planar Defects ◽  
Transmission Electron ◽  
Metal Organic ◽  
Scanning Force

AbstractThe results of a systematic investigation by transmission electron microscopy (TEM), cathodoluminescence (CL), Rutherford backscattering (RBS), X-ray diffraction and topography and scanning force microscopy (SFM) techniques on several InGaAs/InP compressive and tensile strained layers covering the misfit range from −2.3 to 1.5×10−2 and grown by the metal organic vapor phase epitaxy (MOVPE) technique are reported. In compressively strained films the same dependence for the residual strain vs the film thickness as for the InGaAs/GaAs is found whereas a different strain release rate and different extended defects are found in tensile stressed InGaAs alloy. In particular in tensile stressed samples, grooves, planar defects and cracks are present in addition to the interfacial network of misfit dislocations. The correlation between the observed planar defects and the mechanisms of strain relaxation in the case of tensile strained layers is discussed.

Strain Relaxation of Self-nanostructured Solution Derived La0.7Sr0.3MnO3 Films

2009 ◽  
Vol 1174 ◽  
Author(s):  
Patricia Abellan ◽  
Sandiumenge Felip ◽  
Cesar Moreno ◽  
Marie-Jose Casanove ◽  
Teresa Puig ◽  
...  
Keyword(s):  
Microstructural Evolution ◽  
Strain Relaxation ◽  
Scanning Force Microscopy ◽  
Misfit Strain ◽  
Relaxation Mechanism ◽  
Space Mapping ◽  
Reciprocal Space ◽  
Reciprocal Space Mapping ◽  
Transmission Electron ◽  
Scanning Force

AbstractThe morphological and microstructural evolution associated with an exsolution driven self-nanostructuration process of La0.7Sr0.3MnO3 films, is investigated using scanning force microscopy, reciprocal space mapping and transmission electron microscopy. The focus is placed on the misfit strain relaxation mechanism. Surfaces with atomically flat terraces are already developed after 1hour at 1000 °C while first fingerprints of phase exsolution do not appear until 9-10 hours. X-ray diffraction reciprocal-space mapping reveals that 24 nm thick films remain strained during the whole microstructural evolution, while 12 hour annealed films undergo almost total plastic relaxation of the misfit strain at a thickness of 60 nm. Overall, these results point to a kinetic limitation of dislocation mechanisms. It is argued that chemical relaxation provides a significant contribution to misfit strain relief.

Misfit dislocations in green-emitting InGaN/GaN quantum well structures

2005 ◽  
Vol 892 ◽  
Author(s):  
Pedro MFJ Costa ◽  
Ranjan Datta ◽  
Menno J Kappers ◽  
Mary E Vickers ◽  
Colin J Humphreys
Keyword(s):  
Quantum Well ◽  
Strain Relaxation ◽  
Vapour Phase ◽  
Misfit Dislocations ◽  
Single Quantum Well ◽  
Vapour Phase Epitaxy ◽  
Quantum Well Structures ◽  
Transmission Electron ◽  
Metal Organic ◽  
Organic Vapour

AbstractMisfit dislocations (MDs) have been observed using transmission electron microscopy (TEM) in InGaN/GaN quantum well (MQW) structures grown under different metal-organic vapour phase epitaxy (MOVPE) regimes and with In-contents equal to or higher than 20%. These dislocations are even observed in a single quantum well 3 nm thick with an In-content of 22%. Conversely, no MDs were observed in QW structures with an In-content of 16%. The presence of MDs in the QW stack leads to strain relaxation which has been confirmed in the indium-rich structures by high resolution X-ray diffraction (HRXRD).

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Very Thick Coherently Strained GexSi1−x Layers Grown in a Narrow Temperature Window

1991 ◽  
Vol 220 ◽  
Author(s):  
C. H. Chern ◽  
K. L. Wang ◽  
G. Bai ◽  
M. -A. Nicolet
Keyword(s):  
Growth Temperature ◽  
Strain Relaxation ◽  
Gas Pressure ◽  
High Density ◽  
Misfit Dislocations ◽  
High Quality ◽  
Strained Layers ◽  
Temperature Window ◽  
Residual Gas

ABSTRACTStrain relaxation of GexSi1−x layers is studied as a function of growth temperature. Extremely thick coherently strained layers whose thicknesses exceed more than fifty times of the critical thicknesses predicted by Matthews and Blakeslee's model were successfully grown by MBE. There exits a narrow temperature window from 310 °C to 350 °C for growing this kind of high quality thick strained layers. Below this temperature window, the layers are poor in quality as indicated from RHEED patterns. Above this window, the strain of the layers relaxes very fast accompanied with a high density of misfit dislocations as the growth temperature increases. Moreover, for samples grown in this temperature window, the strain relaxation shows a dependence of the residual gas pressure, which has never been reported before.

Stress Relaxation in Uniquely Oriented SiGe/Si Epitaxial Layers

1999 ◽  
Vol 594 ◽  
Author(s):  
M. E. Ware ◽  
R. J. Nemanich
Keyword(s):  
Stress Relaxation ◽  
Surface Morphology ◽  
Strain Relaxation ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Deposited Films

AbstractThis study explores stress relaxation of epitaxial SiGe layers grown on Si substrates with unique orientations. The crystallographic orientations of the Si substrates used were off-axis from the (001) plane towards the (111) plane by angles, θ = 0, 10, and 22 degrees. We have grown 100nm thick Si(1−x) Ge(x) epitaxial layers with x=0.3 on the Si substrates to examine the relaxation process. The as-deposited films are metastable to the formation of strain relaxing misfit dislocations, and thermal annealing is used to obtain highly relaxed films for comparison. Raman spectroscopy has been used to measure the strain relaxation, and atomic force microscopy has been used to explore the development of surface morphology. The Raman scattering indicated that the strain in the as-deposited films is dependent on the substrate orientation with strained layers grown on Si with 0 and 22 degree orientations while highly relaxed films were grown on the 10 degree substrate. The surface morphology also differed for the substrate orientations. The 10 degree surface is relatively smooth with hut shaped structures oriented at predicted angles relative to the step edges.

Examination of Atomic (Scanning) Force Microscopy Probe Tips with the Transmission Electron Microscope

1997 ◽  
Vol 3 (3) ◽  
pp. 203-213 ◽  
Author(s):  
J.A. DeRose ◽  
J.-P. Revel
Keyword(s):  
Atomic Force Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Scanning Force Microscopy ◽  
Image Deconvolution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Force

Abstract: We have developed a method for the examination of atomic force microscopy (scanning force microscopy) tips using a high-resolution transmission electron microscope (TEM). The tips can be imaged in a nondestructive way, enabling one to observe the shape of an atomic force microscope probe in the vicinity of the apex with high resolution. We have obtained images of atomic force microscopy probes with a resolution on the order of 1 nm. The tips can be imaged repeatedly, so one can examine tips before and after use. We have found that the tip can become blunted with use, the rate of wear depending upon the sample and tip materials and the scanning conditions. We have also found that the tips easily accrue contamination. We have studied both commercially produced tips, as well as tips grown by electron beam deposition. Direct imaging in the TEM should prove useful for image deconvolution methods because one does not have to make any assumptions concerning the general shape of the tip profile.

Transmission electron microscopy of misfit dislocation and strain relaxation in lattice mismatched III-V heterostructures versus substrate surface treatment

2011 ◽  
Vol 1324 ◽  
Author(s):  
Y. Wang ◽  
P. Ruterana ◽  
L. Desplanque ◽  
S. El Kazzi ◽  
X. Wallart
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Treatment ◽  
Substrate Surface ◽  
Strain Relaxation ◽  
Dislocation Core ◽  
Misfit Dislocations ◽  
Heteroepitaxial Growth ◽  
Transmission Electron ◽  
Growth Initiation

ABSTRACTHigh resolution transmission electron microscopy in combination with geometric phase analysis is used to investigate the interface misfit dislocations, strain relaxation, and dislocation core behavior versus the surface treatment of the GaAs for the heteroepitaxial growth of GaSb. It is pointed out that Sb-rich growth initiation promotes the formation of a high quality network of Lomer misfit dislocations that are more efficient for strain relaxation.

Transition From Inclined to In-Plane 60° Misfit Dislocations in a Diffuse Interface

1993 ◽  
Vol 319 ◽  
Author(s):  
X. J. Ning ◽  
P. Pirouz
Keyword(s):  
Strain Relaxation ◽  
Classical Model ◽  
Diffuse Interface ◽  
Misfit Dislocations ◽  
Dislocation Loops ◽  
Boron Diffusion ◽  
Plan View ◽  
Transmission Electron ◽  
Mechanisms Of Formation ◽  
Film Substrate

AbstractDespite tremendous activity during the last few decades in the study of strain relaxation in thin films grown on substrates of a dissimilar material, there are still a number of problems which are unresolved. One of these is the nature of misfit dislocations forming at the film/substrate interface: depending on the misfit, the dislocations constituting the interfacial network have predominantly either in-plane or inclined Burgers vectors. While, the mechanisms of formation of misfit dislocations with inclined Burgers vectors are reasonably well understood, this is not the case for in-plane misfit dislocations whose formation mechanism is still controversial. In this paper, misfit dislocations generated to relax the strains caused by diffusion of boron into silicon have been investigated by plan-view and crosssectional transmission electron microscopy. The study of different stages of boron diffusion shows that, as in the classical model of Matthews, dislocation loops are initially generated at the epilayer surface. Subsequently the threading segments expand laterally and lay down a segment of misfit dislocation at the diffuse interface. The Burgers vector of the dislocation loop is inclined with respect to the interface and thus the initial misfit dislocations are not very efficient. However, as the diffusion proceeds, non-parallel dislocations interact and give rise to product segments that have parallel Burgers vectors. Based on the observations, a model is presented to elucidate the details of these interactions and the formation of more efficient misfit dislocations from the less-efficient inclined ones.

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