Defect Structures in Epitaxially Grown InAs Films on InP Substrates

1991 ◽  
Vol 238 ◽  
Author(s):  
A. K. Ballal ◽  
L. Salamanca-Riba ◽  
D. L. Partin ◽  
J. Heremans ◽  
L. Green ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Organic Chemical ◽  
Misfit Dislocations ◽  
Defect Structures ◽  
Substrate Interface ◽  
Film Substrate ◽  
Inp Substrates

ABSTRACTIn this paper we study the lattice-mismatch induced defect structures of InAs films grown on semi-insulating InP substrates using metal organic chemical vapor deposition. The defect structure studies were carried out on films of equal total thicknesses but for different duration for nucleation of a layer of InAs deposited at low temperature on the substrate. Misfit strain is caused by the inherent lattice mismatch of approximately three percent and this is partially relieved by the generation of misfit dislocations at the film/substrate interface. Transmission electron microscopy studies show the presence of an intrinsic strain and the generation of thermal etchpits at the heteroepitaxial interface. Our studies show that there is a direct correlation between the density of dislocations generated at the film/substrate interface and the duration of nucleation of the film on the substrate. Dislocation densities at the surface of the InAs films and at the heteroepitaxial interface differed by almost two orders of magnitude. High resolution electron microscopy reveals abrupt and sharp interfaces in films with thick nucleation layers and also confirms that the lattice mismatch is partially accommodated by the generation of misfit dislocations at the film/substrate interface.

Defect Characterization of InAs Films Grown by Two-Step MOCVD on (100) InP Substrates

1992 ◽  
Vol 280 ◽  
Author(s):  
A. K. Ballal ◽  
L. Salamanca-Riba ◽  
D. L. Partin
Keyword(s):  
Electron Microscopy ◽  
Lattice Mismatch ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Plan View ◽  
Inp Substrates

ABSTRACTIn this paper we investigate the defect morphology and misfit strain in InAs films grown on (100) InP substrates using two-step metal organic chemical vapor deposition (MOCVD). High quality InAs films were obtained despite the 3.2% lattice-mismatch between the InAs film and the InP substrate. Cross-sectional and plan-view transmission electron microscopy has been used to characterize the ∼3μm thick InAs films. Almost all the lattice mismatch is accomodated by an orthogonal array of pure edge Lomer dislocations which are favored over the 60° type since they are more efficient in relieving misfit strain. In addition to misfit dislocations, threading dislocations were observed propagating through the film. Most of the threading dislocations were 60° type dislocations along the < 211 > and < 110 > directions on inclined {111} planes. The threading dislocations originate from island coalescence during film growth. High resolution electron microscopy shows the epitaxial relationship between the film and the substrate and reveals an abrupt and sharp interface with periodic dislocation cores.

HIGH RESOLUTION ELECTRON MICROSCOPE STUDY OF CdTe-Cd0.6Mn0.4 Te SUPERLATTICES

1985 ◽  
Vol 56 ◽  
Author(s):  
C. CHOI ◽  
N. OTSUKA ◽  
L. A. KOLODZIEJSKI ◽  
R. L. GUNSHOR-a
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Contrast ◽  
Electron Microscope Study ◽  
Lattice Mismatch ◽  
Thick Layer ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
High Resolution Electron Microscope

AbstractStructures of CdTe-Cd0.6Mn0.4Te superlattices which are caused by the lattice mismatch between suterlattice layers have been studied by high resolution electron microscopy (HREM). In thin-layer superlattices, the crystal lattice in each layeris elastically distorted, resulting in the change of the crystal symmetry from cubic to rhombohedral. The presence of the small rhombohedral distrotion has been confirmed through a phase contrast effect in HREM images. In a thick-layer superlattice, the lattice mismatch is accommodated by dissociated misfit dislocations. Burgers vectors of partial misfit dislocations have been identified from the shift of lattice fringes in HREM images.

Epitaxial Growth and Structure of Cubic and Pseudocubic Perovskite Films on Perovskite Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
P. A. Langjahr ◽  
T. Wagner ◽  
M. RÜhle ◽  
F. F. Lange
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Ternary Oxide ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Resolution Electron

AbstractCubic and pseudocubic perovskite films on perovskite substrates are used to study the influence of the lattice mismatch on the epitaxial growth of thin films on substrates of the same structure. For the growth of the films, a metalorganic decomposition route (MOD) using 2-ethylhexanoates and neodecanoates as precursors, was developed. The decomposition of the precursors was investigated with thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The films were spin-coated on (001)-oriented SrTiO3- and LaAlO3-substrates, pyrolyzed and afterwards annealed between 600°C and 1200°C. XRD-nvestigations and conventional transmission electron microscopy (CTEM) show, that epitaxial films with the orientation relationship [100](001) film ║ [100](001) substrate can be grown. With XRD, it could be shown, that not only ternary oxide films (SrZrO3, BaZrO3 and BaCeO3), but also perovskite solid solution films (SrTi0.5Zr0.5O3and BaCe0.5Zr0.5O3) can be prepared. Strong interdiffusion, detected by a shift of the film lattice parameter towards the substrate lattice parameter was found in SrZrO3- and BaZrO3-films on SrTiO3, annealed at temperatures above 1050°C. High resolution electron microscopy (HREM) studies of SrZrO3 on SrTiO3 show that a crystalline semicoherent interface with a periodical array of misfit dislocations is present.

Variant structure in metal-organic-chemical-vapor-deposition-derived SnO2 thin films on sapphire (0001)

1995 ◽  
Vol 10 (6) ◽  
pp. 1516-1522 ◽  
Author(s):  
Donhang Liu ◽  
Q. Wang ◽  
H.L.M. Chang ◽  
Haydn Chen
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Organic Chemical ◽  
Metal Organic ◽  
Film Substrate ◽  
Organic Chemical Vapor Deposition

Tin oxide (SnO2) thin films were deposited on sapphire (0001) substrate by metal-organic chemical vapor deposition (MOCVD) at temperatures of 600 and 700 °C. The microstructure of the deposited films was characterized by x-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). At the growth conditions studied, films were single-phase rutile and epitaxial, but showed variant structures. Three distinct in-plane epitaxial relationships were observed between the films and the substrate. A crystallographic model is proposed to explain the film morphology. This model can successfully predict the ratio of the width to the length of an averaged grain size based upon the lattice mismatch of the film-substrate interface.

High Resolution Transmission Electron Microscopy Investigation of the Defect Structure in CdMnTe Layers Grown on GaAs by MOCVD

1987 ◽  
Vol 102 ◽  
Author(s):  
J. H. Mazur ◽  
P. Grodzinski ◽  
A. Nouhi ◽  
R. J. Stirn
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Organic Chemical ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Resolution Electron

ABSTRACTElectron diffraction and high resolution electron microscopy were used for analysis of Cd1−xMnxTe films grown on (100)2°[011] GaAs substrates by metal organic chemical vapor deposition (MOCVD) at 420°C (x=O.3) and 450°C (x=0.5). It has been found that these two conditions produce dramatically different microstructures. Two orientation relationships of the epilayers with respect to the substrate were observed. It is suggested that this phenomenon may be related to GaAs substrate surface morphology.

HREM study of heteroepitaxial interfaces in the Ni.50Co.50O/Al2MgO4(100) system

1992 ◽  
Vol 50 (1) ◽  
pp. 374-375
Author(s):  
W. Cao ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Film ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Epitaxial Films ◽  
Critical Factors ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Film Substrate

Epitaxial CoO/NiO multilayers and alloys have been produced which show interesting structural and magnetic properties. Typically, epitaxial films are grown either by chemical vapor deposition or evaporation. However, sputtering can also yield high quality epitaxial films. The structure of the substrate and the interface of the film/substrate are critical factors to determine the quality of the epitaxial film. The CoO/NiO epitaxial films on the α-Al2O3 had been studied extensively in our previous work. In this paper, the heteroepitaxial interface in the Ni.50Co.50O/Al2MgO4 is studied by using high resolution electron microscopy. Transmission electron microscopy was performed using the JEOL-200CX and JEOL-ARM1000 microscopes at the National Center for Electron Microscopy, Berkeley.

Structural properties of epitaxial TiO2 films grown on sapphire (11$\overline 1$0) by MOCVD

1992 ◽  
Vol 7 (9) ◽  
pp. 2495-2506 ◽  
Author(s):  
H.L.M. Chang ◽  
H. You ◽  
Y. Gao ◽  
J. Guo ◽  
C.M. Foster ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Properties ◽  
Growth Temperature ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Organic Chemical ◽  
Resolution Electron ◽  
Titanium Dioxide Thin Films ◽  
Deposited Films

Titanium dioxide thin films were grown on sapphire (11$\overline 1$0) substrates in a low-pressure metal-organic chemical vapor deposition system at temperatures ranging from 400 to 800 °C. Raman scattering, x-ray diffraction, transmission electron microscopy, and high resolution electron microscopy techniques were employed to characterize the structural properties of the deposited films. The resultant phases and structures of the deposited films depended on both the growth temperature and the substrate surface properties (surface imperfections, steps, etc.). At the growth temperature of 800 °C, single-crystal rutile films were obtained reproducibly with two possible epitaxial relationships. At lower temperatures (400 to 775 °C), the deposited films can be epitaxial or polycrystalline with highly oriented grains. The similarity between the atomic arrangements of the substrate and the film is discussed in detail to explain the observed epitaxial relationships and abruptness of the interfaces.

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).

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