Evolution of Stress and Relaxation of Strain of Ge and SiGe Alloy Films on Si(001)

2001 ◽  
Vol 696 ◽  
Author(s):  
R. Koch ◽  
J. J. Schulz ◽  
B. Wassermann ◽  
G. Wedler
Keyword(s):  
Strain Relaxation ◽  
Misfit Strain ◽  
Growth Mode ◽  
Ex Situ ◽  
Scanning Tunneling ◽  
Misfit Dislocations ◽  
Tunneling Microscopy ◽  
Structural Investigations ◽  
Alloy Films ◽  
Sige Alloy

AbstractWe report on real time stress measurements by a sensitive cantilever beam technique of Ge and SiGe Alloy Films on Si(001) in combination with structural investigations by in situ STM (scanning tunneling microscopy) and ex situ AFM (atomic force microscopy). Characteristic features in the stress curves provide detailed insight into the development and relief of the misfit strain as well as the respective growth mode. For the Stranski-Krastanow system Ge/Si(001) the strain relaxation proceeds mainly in two steps: (i) by the formation of 3D islands on top of the Ge wetting layer and (ii) via misfit dislocations in larger 3D islands and upon their percolation. Co-deposition of Si influences the stress behavior drastically. The growth mode changes from Stranski-Krastanow to a kinetic 3D island mode at Si concentrations of about 20% leading to the so far smallest quantum dots of the Ge/Si system.

A Model for Lattice-Mismatched Epitaxy: A Continuum View

1992 ◽  
Vol 280 ◽  
Author(s):  
B. G. Orr ◽  
C. W. Snyder
Keyword(s):  
Surface Diffusion ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
High Energy ◽  
Growth Mode ◽  
Scanning Tunneling ◽  
Physical Factors ◽  
Diffusion Kinetics ◽  
Tunneling Microscopy ◽  
Lattice Mismatched Epitaxy

To date, primarily only idealized equilibrium models for the growth mode and strain relaxation of elastically strained overlayers have been proposed. Here we present a general continuum model for lattice-mismatched epitaxy. As molecular beam epitaxy is inherently a nonequilibrium growth process, surface diffusion kinetics is incorporated in the model. Additionally, a new strain relaxation mechanism in a dislocation-free film is considered. Experimental support for our view is obtained from measurements made by reflection high energy electron diffraction, scanning tunneling microscopy, and transmission electron microscopy on the growth of InGaAs on GaAs(100). These results demonstrate the strong effects which strain, surface diffusion kinetics, and surface energy have on growth mode. From analytical and numerical analysis in 1 + 1 dimensions, the interrelationship of such physical factors is revealed. Our improved understanding enables control over the growth behavior of strained-layer superlattices and heterostructures.

Surface evolution of strained SrRuO3 films deposited at various temperatures on SrTiO3 (001) substrates

2006 ◽  
Vol 21 (6) ◽  
pp. 1550-1560 ◽  
Author(s):  
Sang Ho Oh ◽  
Chan Gyung Park
Keyword(s):  
Epitaxial Growth ◽  
Ion Beam ◽  
Strain Relaxation ◽  
Scanning Tunneling ◽  
Misfit Dislocations ◽  
Ion Beam Sputtering ◽  
Ambient Conditions ◽  
Tunneling Microscopy ◽  
Surface Evolution ◽  
Relaxation Stage

Surface evolution was studied for strained SrRuO3 films with a nominal 75 nm thickness deposited at various substrate temperatures (650–850 °C). Epitaxial growth of the films was achieved on single TiO2-terminated SrTiO3 (001) substrates by using ion-beam sputtering. The surface morphology of the deposited films was investigated by scanning tunneling microscopy in ambient conditions, and their microstructure was characterized by transmission electron microscopy. The self-organized step-terrace structure was observed for the films deposited at lower than 800 °C, suggesting that the epitaxial growth proceeded by step-flow growth. In particular, each film showed characteristic surface evolutions pertinent to the misfit strain relaxation stage, mostly influenced by the moving segment of misfit dislocations threading up to the surface: surface undulations for the film at the initial stage of relaxation (deposited at 650 °C), circular growth spirals during the relaxation stage (700 °C), and well-ordered step-terrace structure after almost full development of misfit dislocations (750 and 800 °C).

Growth of Si on Ge(001)2×l by gas-source molecular beam epitaxy

1993 ◽  
Vol 51 ◽  
pp. 806-807
Author(s):  
H.Z. Xiao ◽  
R. Tsu ◽  
I.M. Robertson ◽  
H.K. Birnbaum ◽  
J.E. Greene
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
High Energy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Gas Source ◽  
High Quality Result ◽  
Strained Layer Superlattices

The growth of SiGe strained-layer superlattices (SLS) has been received considerable attention due to the electronic and optoelectronic properties of these layers. In addition, these structures offer tantalizing possibilities for "band gap engineering" through the use of strain and chemically ordered alloys. The remaining barriers to grow the SiGe SLS structures with high quality result from the generation of large densities of defects, such as dislocations, twins, stacking faults, etc., at the heterointerfaces arising from the misfit strain relaxation. Other problems associated with the growth of the SiGe SLS structures are segregation and low incorporation of the dopants and inter-diffusion of Si and Ge. In the present study, the inter-mixing of Si and Ge and the generation of the defects in Si epilayers grown on Ge(001)2×1 at 550 °C by gas-source molecular beam epitaxy (MBE) from Si2H6 were studied using transmission electron microscopy (TEM), in-situ reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM) and electron energy-loss spectroscopy (EELS).

COMBINED HRLEED AND STM INVESTIGATIONS ON THE INITIAL STAGES OF Cu HETEROEPITAXY Ru(0001)

1997 ◽  
Vol 04 (06) ◽  
pp. 1167-1171 ◽  
Author(s):  
CH. AMMER ◽  
K. MEINEL ◽  
H. WOLTER ◽  
A. BECKMANN ◽  
H. NEDDERMEYER
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Strain Relaxation ◽  
Local Scale ◽  
Low Energy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Layer Structures ◽  
Low Energy Electron

Recent scanning tunneling microscopy (STM) observations revealed different layer structures in the heteroepitaxial Cu/Ru(0001) system with increasing film thickness attributed to various stages of strain relaxation. High-resolution low-energy electron diffraction (HRLEED) analysis permits one to derive more exactly both lattice periodicities and lattice rotations. Furthermore, the representative character of local STM results can be proved. However, STM measurements are needed to identify and to assign the satellite spots to coexistent different superstructures which are superposed incoherently in the diffraction pattern. Generally, the integral LEED results confirm the crystallographic data obtained by STM in a local scale.

Growth mode of 2-mercaptobenzoxazole on Cu(100) studied by scanning tunneling microscopy

2000 ◽  
Vol 470 (1-2) ◽  
pp. L7-L12 ◽  
Author(s):  
G. Contini ◽  
V.Di Castro ◽  
A. Angelaccio ◽  
N. Motta ◽  
A. Sgarlata
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Growth Mode ◽  
Scanning Tunneling ◽  
Tunneling Microscopy

Mechanisms of misfit strain relaxation in epitaxially grown BLT (Bi4-xLaxTi3O12, x = 0.75) thin films

2003 ◽  
Vol 779 ◽  
Author(s):  
Hyung Seok Kim ◽  
Sang Ho Oh ◽  
Ju Hyung Suh ◽  
Chan Gyung Park
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
20 Nm

AbstractMechanisms of misfit strain relaxation in epitaxially grown Bi4-xLaxTi3O12 (BLT) thin films deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, that was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (~1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film.

Microwave Phase Shifters: Epitaxial Growth by Pulsed Laser Deposition of Dielectric Ba0.5Sr0.5TiO3 Thin Films on MgO

2005 ◽  
Vol 902 ◽  
Author(s):  
YauYau Tse ◽  
P. S. Suherman ◽  
T. J. Jackson ◽  
I. P. Jones
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Strain Relaxation ◽  
Pulsed Laser ◽  
Phase Shifters ◽  
Laser Deposition ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Epitaxial Relationship

AbstractBa0.5Sr0.5TiO3 (BSTO) thin films were grown on (001) MgO using pulsed-laser deposition (PLD). The microstructures of in-situ and ex-situ annealed BSTO films were studied by X-ray diffraction and transmission electron microscopy (TEM). The films showed a cube on cube epitaxial relationship with <100> BSTO // <100> MgO. They were essentially single crystals with a columnar structure and possessed smooth surfaces. The interfaces of the BSTO films and substrates were atomically sharp, with misfit dislocations. Better crystallinity and full strain relaxation was obtained in films grown in 10-1 mbar oxygen and annealed ex-situ. A 30% increase in dielectric tuneability was achieved compared with in-situ annealing and deposition at 10-4 mbar. Threading dislocations are the dominant defects in the films grown in 10-1 mbar oxygen and annealed ex-situ, while the films with in-situ annealing show columnar structures with low angle boundaries.

SiC SURFACE RECONSTRUCTION: RELEVANCY OF ATOMIC STRUCTURE FOR GROWTH TECHNOLOGY

1999 ◽  
Vol 06 (06) ◽  
pp. 1129-1141 ◽  
Author(s):  
U. STARKE ◽  
J. BERNHARDT ◽  
J. SCHARDT ◽  
K. HEINZ
Keyword(s):  
Silicon Oxide ◽  
Electronic Device ◽  
Defect Density ◽  
Ex Situ ◽  
Scanning Tunneling ◽  
Hydrogen Treatment ◽  
Tunneling Microscopy ◽  
Layer Stacking ◽  
Device Applications ◽  
Sic Wafer

Growth of SiC wafer material, of heterostructures with alternating SiC crystal modifications (polytypes), and of oxide layers on SiC are of importance for potential electronic device applications. By investigation of hexagonal SiC surfaces the importance of atomic surface structure for control of the respective growth processes involved is elucidated. Different reconstruction phases prepared by ex situ hydrogen treatment or by Si deposition and annealing in vacuum were analyzed using scanning tunneling microscopy (STM), Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED) crystallography. The extremely efficient dangling bond saturation of the SiC(0001)-(3×3) phase allows step flow growth for monocrystalline homoepitaxial layers. A switch to cubic layer stacking can be induced on hexagonal SiC(0001) samples when a [Formula: see text] phase is prepared. This might serve as seed for polytype heterostructures. Finally, we succeeded in preparing an epitaxially well matching silicon oxide monolayer with [Formula: see text] periodicity on both SiC(0001) and SiC[Formula: see text]. This initial layer promises to facilitate low defect density oxide films for MOS devices.

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