Transmission electron microscopy observation and optical property of sol-gel derived LiNbO3 films

1996 ◽  
Vol 11 (12) ◽  
pp. 3152-3157 ◽  
Author(s):  
K. Terabe ◽  
A. Gruverman ◽  
Y. Matsui ◽  
N. Iyi ◽  
K. Kitamura
Keyword(s):  
Lattice Mismatch ◽  
Sol Gel ◽  
Misfit Dislocations ◽  
Microscopy Observation ◽  
Continuous Film ◽  
Transmission Electron ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Interface Structures ◽  
Optical Waveguiding

Crystallization behavior, defects, and interface structures of sol-gel derived LiNbO3 films on three kinds of substrates were examined. The nucleation was found to occur epitaxially at the interface between the film and the substrate. The continuous film is formed by coalescence of the island-like crystallites. When sapphire substrate is used, which has large lattice mismatch with the LiNbO3, the resulting film contains a large amount of micropores, twin structures, and misfit dislocations. On the other hand, while LiTaO3 and 5% MgO-doped LiNbO3 substrates with smaller mismatch are used as substrates, the films show no evidence of the formation of dislocations and twins. The film on 5% MgO-doped LiNbO3 substrate shows better optical waveguiding property.

Equilibrium Analysis of Lattice-Mismatched Nanowire Heterostructures

2002 ◽  
Vol 737 ◽  
Author(s):  
E. Ertekin ◽  
P.A. Greaney ◽  
T. D. Sands ◽  
D. C. Chrzan
Keyword(s):  
Simple Model ◽  
Misfit Dislocation ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Equilibrium Analysis ◽  
Misfit Dislocations ◽  
Model Based ◽  
Large Lattice ◽  
Large Lattice Mismatch

ABSTRACTThe quality of lattice-mismatched semiconductor heterojunctions is often limited by the presence of misfit dislocations. Nanowire geometries offer the promise of creating highly mismatched, yet dislocation free heterojunctions. A simple model, based upon the critical thickness model of Matthews and Blakeslee for misfit dislocation formation in planar heterostructures, illustrates that there exists a critical nanowire radius for which a coherent heterostructured nanowire system is unstable with respect to the formation of misfit dislocations. The model indicates that within the nanowire geometry, it should be possible to create perfect heterojunctions with large lattice-mismatch.

Nucleation of misfit and threading dislocations in GaSb/GaAs(001) heterostructure

1996 ◽  
Vol 54 ◽  
pp. 946-947
Author(s):  
W. Qian ◽  
M. Skowronski ◽  
R. Kaspi ◽  
M. De Graef
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Extended Defects ◽  
Large Lattice ◽  
Threading Dislocation Density ◽  
Small Lattice ◽  
Large Lattice Mismatch

GaSb thin film grown on GaAs is a promising substrate for fabrication of electronic and optical devices such as infrared photodetectors. However, these two materials exhibit a 7.8% lattice constant mismatch which raises concerns about the amount of extended defects introduced during strain relaxation. It was found that, unlike small lattice mismatched systems such as InxGa1-xAs/GaAs or GexSi1-x/Si(100), the GaSb/GaAs interface consists of a quasi-periodic array of 90° misfit dislocations, and the threading dislocation density is low despite its large lattice mismatch. This paper reports on the initial stages of GaSb growth on GaAs(001) substrates by molecular beam epitaxy (MBE). In particular, we discuss the possible formation mechanism of misfit dislocations at the GaSb/GaAs(001) interface and the origin of threading dislocations in the GaSb epilayer.GaSb thin films with nominal thicknesses of 5 to 100 nm were grown on GaAs(001) by MBE at a growth rate of about 0.8 monolayers per second.

Nanopattern Formation by Periodic Array of Interfacial Misfit Dislocations in Bi(111)/Si(001) Heteroepitaxy

2007 ◽  
Vol 1059 ◽  
Author(s):  
Giriraj Jnawali ◽  
H. Hattab ◽  
C. Bobisch ◽  
A. Bernhart ◽  
E. Zubkov ◽  
...  
Keyword(s):  
Elasticity Theory ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Periodic Array ◽  
Misfit Dislocations ◽  
Strain Fields ◽  
Edge Type ◽  
Large Lattice ◽  
Large Lattice Mismatch

ABSTRACTDespite their large lattice mismatch of 18 %, the lattices of Bi(111) and Si(001) fit surprisingly well. A remaining compressive strain in the Bi film of 2.3 % along the direction is accommodated by the formation of a periodic array of edge-type misfit dislocations confined to the interface. The strain fields surrounding each dislocation interact with each other, producing a quasi-periodic nanopattern of grating-like periodic height undulations on the surface. The separation and the amplitude of the height undulations have been derived by spot profile analyzing LEED and STM surface height profiles. The observed undulations agree well with elasticity theory.

Epitaxial Growth of 3C-SiC on T-shape columnar Si Substrates

2004 ◽  
Vol 815 ◽  
Author(s):  
S. Nishino ◽  
A. Shoji ◽  
T. Nishiguchi ◽  
S. Ohshima
Keyword(s):  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Misfit Dislocations ◽  
High Electron ◽  
Large Area ◽  
Si Substrates ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Cubic Silicon Carbide

AbstractCubic silicon carbide (3C-SiC) is a suitable semiconductor material for high temperature, high power and high frequency electronic devices, because of its wide bandgap, high electron mobility and high saturated electron drift velocity. The usage of Si substrates has the advantage of large area substrates for the growth of 3C-SiC layers. However, large lattice mismatch between 3C-SiC and Si (>20%) has caused the generation of defects such as misfit dislocations, twins, stacking faults and threading dislocations at the SiC/Si interface. Lateral epitaxial overgrowth (ELOG) of 3C-SiC on Si substrates using SiO2 has been reported to reduce the defect density. In this report, epitaxial growth of 3C-SiC on T-shape patterned (100) Si substrates has been investigated to reduce interfacial defects.

Epitaxial Growth in Large Lattice Mismatch Systems: Characteristics of Domain Epitaxy

1992 ◽  
Vol 280 ◽  
Author(s):  
Tsvetanka S. Zheleva ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Epitaxial Growth ◽  
Interfacial Energy ◽  
Lattice Mismatch ◽  
Misfit Dislocations ◽  
Orientation Relationships ◽  
Epitaxial Relationship ◽  
Model Calculations ◽  
Large Lattice ◽  
Large Lattice Mismatch

ABSTRACTThe characteristics of epitaxial growth in large lattice mismatch TiN/Si and TiN/GaAs systems are analyzed. The epitaxial growth in these large mismatch systems is modelled in terms of various energy contributions to the epilayer. The new mode of growth, defined as domain epitaxial growth in these high mismatch systems is maintained by the formation of misfit dislocations at repeated intervals. The epitaxial relationship within the domain consists of n interplanar distances of the overlayer film closely matching with m interplanar distances of the substrate, where m and n are integers. The interfacial energy is found to be a very important term in determining the orientation relationships. The results of the model calculations are compared with the experimental observations.

Characterization of Interfacial Structure in Large Lattice Mismatch Heteroepitaxy: Ag/Si (111)

1990 ◽  
Vol 209 ◽  
Author(s):  
D.C. McKenna ◽  
G.-C. Wang ◽  
K. Rajan
Keyword(s):  
Lattice Mismatch ◽  
Interfacial Structure ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Diffraction Patterns

ABSTRACTThe interfacial structure of a large lattice mismatched (˜25%) (111) Ag-Si system was studied by using transmission electron diffraction (SADP - Selected Area Diffraction Pattern). The epitaxial films of Ag (600–1200Å) were grown by MBE on flat Si(111) and misoriented Si(1ll) surfaces. We have examined the interfacial structures of the Ag on 2° misoriented Si(111) using diffraction patterns of cross sectional view. Through a detail analysis of thelocation and shape of the diffraction spots, we can determine the epitaxial relationship between Ag and Si, the small tilt angle of Ag(111) planes withrespect to the misoriented Si(111), the period of the finite terrace size of the misoriented Si substrate, and the size of the ordered region in the Ag film. The O-lattice analysis developed by Bollmann has beenapplied to this interface andthe result is compared with the SADP observation.

Unique Defect-Induced Donor Structure at the Lattice Mismatched InAs/GaP Heterointerface

1998 ◽  
Vol 535 ◽  
Author(s):  
V. Gopal ◽  
E.-H. Chen ◽  
E. P. Kvam ◽  
J. M. Woodall
Keyword(s):  
Lattice Mismatch ◽  
Misfit Dislocations ◽  
High Electron ◽  
Epitaxial Relationship ◽  
Band Gap Engineering ◽  
Large Lattice ◽  
Device Applications ◽  
Direct Growth ◽  
Large Lattice Mismatch ◽  
Hall Sensors

AbstractWe have investigated the direct growth of narrow-gap InAs on wide-gap GaP by Molecular Beam Epitaxy. InAs and GaP have the largest mismatch among all the III-arsenides and the III-phosphides – 11%. A perfect epitaxial relationship is maintained between the InAs and the GaP despite the large lattice mismatch. Moreover, a reproducible defect structure with unique electronic properties is developed at the heterointerface. A point defect associated with the intersection of 90° misfit dislocations may act as an ordered, structural dopant. This dopant is fully ionized with a constant, high sheet carrier density of 1013 cm−2, independent of InAs layer thickness, and exhibits no freeze out even at 5 K. Device applications for such a system include temperature insensitive Hall sensors. We have also demonstrated high electron mobilities (over 10000 cm2/V-sec) in nominally undoped thick InAs layers grown on GaP. The explanation of this effect is presented to emphasize the exciting possibilities of band gap engineering in this system.

Characteristics of titanium oxide films deposited by an activated reactive evaporation method

1994 ◽  
Vol 9 (6) ◽  
pp. 1468-1473 ◽  
Author(s):  
Tatsuo Fujii ◽  
Naoki Sakata ◽  
Jun Takada ◽  
Yoshinari Miura ◽  
Yoshihiro Daitoh ◽  
...  
Keyword(s):  
Titanium Oxide ◽  
Lattice Mismatch ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Rutile Structure ◽  
Evaporation Method ◽  
Reactive Evaporation ◽  
Transmission Electron ◽  
Large Lattice Mismatch ◽  
Activated Reactive Evaporation

Titanium di- and sesquioxide films were epitaxially grown on the (001) surface of sapphire single-crystalline substrates by an activated reactive evaporation method. Formation range for each titanium oxide was determined as a function of oxygen pressure (Po2) by means of x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Films prepared at Po2 ≥ 2.0 × 10−4 Torr were stoichiometric (100)-oriented rutile of TiO2, and with decreasing Po2 they would accommodate more and more Ti3+ ions in the rutile structure. At Po2 = 0.6 × 10−4 Torr, on the other hand, (001)-oriented Ti2O3 was formed and an electrical transition was clearly detected at about 400 K. However, the large lattice mismatch between the substrate and these films leads to a periodic introduction of misfit dislocations in the case of the TiO2 films and a mixing of stacking sequences for the Ti2O3 films.

Structural Effects in Al(111)/Si(111) Heteroepitaxy by Partially Ionized Beam Deposition α

1988 ◽  
Vol 116 ◽  
pp. 465-470 ◽  
Author(s):  
A. S. Yapsir ◽  
C.-H. Choi ◽  
S. N. Yang ◽  
T.-M. Lu ◽  
M. Madden ◽  
...  
Keyword(s):  
Single Crystal ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
Atom Ratio ◽  
Transmission Electron ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Partially Ionized ◽  
Acceleration Voltage

AbstractSingle crystal Al(111) films were grown on Si(111) surface at room temperature under a conventional vacuum condition using the partially ionized beam (PIB) deposition technique. The Al films were deposited with an ion to atom ratio of about 0.3% and an acceleration voltage of 1 kV. Transmission electron microscopy (TEM) analysis showed that the as-deposited films were single crystal with certain density of dislocation networks. These dislocations disappeared following a heat treatment at 450°C for 30 min. From X-ray diffraction and TEM patterns, it was observed that the Al(111) was aligned to the substrate with Al<1l0>//Si<1l0>. Possible mechanisms of the PIB epitaxial growth and a novel structural defect that is unique to this large lattice mismatch system are discussed.

Structural Studies of an InAs-GaAs Superlattice Alloy

1985 ◽  
Vol 47 ◽  
Author(s):  
M. C. Tamargo ◽  
R. Hull ◽  
L. H. Greene ◽  
J. R. Hayes ◽  
N. Tabatabaie ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Layer Structure ◽  
Growth Conditions ◽  
Buffer Layers ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Strained Layer Superlattices ◽  
Lattice Matched

ABSTRACTThin alternating layers of InAs and GaAs have been grown by MBE on buffer layers lattice matched to InP. The layer structure was evaluated by transmission electron microscopy (TEM) and low angle X-ray scattering. Commensurate epitaxial layers approximately 15Å thick were obtained in spite of the large lattice mismatch (7%). These results and their implication for growth conditions of strained-layer superlattices will be discussed.

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