Strain Relaxation in Si1-xGex Thin Films on Si (100) Substrates: Modeling and Comparisons with Experiments

AbstractStrained semiconductor thin films grown epitaxially on semiconductor substrates of different composition, such as Si1-xGex/Si, are becoming increasingly important in modern microelectronic technologies. In this paper, we report a hierarchical computational approach for analysis of dislocation formation, glide motion, multiplication, and annihilation in Si1-xGex epitaxial thin films on Si substrates. Specifically, a condition is developed for determining the critical film thickness with respect to misfit dislocation generation as a function of overall film composition, film compositional grading, and (compliant) substrate thickness. In addition, the kinetics of strain relaxation in the epitaxial film during growth or thermal annealing (including post-implantation annealing) is analyzed using a properly parameterized dislocation mean-field theoretical model, which describes plastic deformation dynamics due to threading dislocation propagation. The theoretical results for Si1-xGex epitaxial thin films grown on Si (100) substrates are compared with experimental measurements and are used to discuss film growth and thermal processing protocols toward optimizing the mechanical response of the epitaxial film.

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Development of Cross-Hatch Morphology During Growth of Lattice Mismatched Layers

MRS Proceedings ◽

10.1557/proc-673-p5.2 ◽

2001 ◽

Vol 673 ◽

Author(s):

A. Maxwell Andrews ◽

J.S. Speck ◽

A.E. Romanov ◽

M. Bobeth ◽

W. Pompe

Keyword(s):

Misfit Dislocation ◽

Film Growth ◽

Strain Relaxation ◽

Dislocation Generation ◽

Force Microscopy ◽

Step Flow ◽

Atomic Force ◽

Subsequent Step ◽

Step Flow Growth ◽

Lateral Scale

ABSTRACTAn approach is developed for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth. It is demonstrated that both strain relaxation associated with misfit dislocation formation and subsequent step elimination (e.g. by step-flow growth) are responsible for the appearance of nanoscopic surface height undulations (0.1-10 nm) on a mesoscopic (∼100 nm) lateral scale. The results of Monte Carlo simulations for dislocation- assisted strain relaxation and subsequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ∼50 Å in an approximately 70% strain relaxed In0.25Ga0.75As layers. The model is supported by atomic force microscopy (AFM) observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation generation.

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Growth study of epitaxial FexZn1−xF2 thin films

Journal of Materials Research ◽

10.1557/jmr.2001.0244 ◽

2001 ◽

Vol 16 (6) ◽

pp. 1769-1775 ◽

Cited By ~ 6

Author(s):

J. McChesney ◽

M. Hetzer ◽

H. Shi ◽

T. Charlton ◽

D. Lederman

Keyword(s):

Thin Films ◽

Film Growth ◽

Magnetic Phase Diagram ◽

Epitaxial Thin Films ◽

X Ray Diffraction ◽

Growth Study ◽

Lattice Match ◽

Different Temperatures ◽

Bulk Single Crystals ◽

The Ideal

The FexZn1−xF2 alloy has been shown to be a model system for studying the magnetic phase diagram of dilute magnets. Whereas the growth of bulk single crystals with fixed Zn concentrations is difficult, the thin film growth is comparatively simpler and more flexible. To gain an understanding of the growth of FexZn1−xF2 films, a method was developed to grow smooth films at fixed concentrations. This was done by depositing a MgF2 buffer layer on MgF2(001) substrates and then depositing FeF2 and ZnF2 [001]-orientated epitaxial thin films at different temperatures. Surprisingly, the lattice spacing depends strongly on the growth temperature, for 44-nm-thick FeF2 films and 77-nm-thick ZnF2 films. This indicates a significant amount of stress, despite the close lattice match between the films and the MgF2 substrate. Thick alloy samples (approximately 500 nm thick) were grown by co-evaporation from the FeF2 and ZnF2 sources at the ideal temperature determined from the growth study, and their concentration was accurately determined using x-ray diffraction.

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Effect of strain relaxation of oxidation-treated SiGe epitaxial thin films and its nanomechanical characteristics

Applied Surface Science ◽

10.1016/j.apsusc.2009.12.022 ◽

2010 ◽

Vol 256 (10) ◽

pp. 3299-3302 ◽

Cited By ~ 9

Author(s):

Bo-Ching He ◽

Hua-Chiang Wen ◽

Tun-Yuan Chinag ◽

Zue-Chin Chang ◽

Derming Lian ◽

...

Keyword(s):

Thin Films ◽

Strain Relaxation ◽

Epitaxial Thin Films

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Donald William Pashley. 21 April 1927 — 16 May 2009

Biographical Memoirs of Fellows of the Royal Society ◽

10.1098/rsbm.2010.0009 ◽

2010 ◽

Vol 56 ◽

pp. 317-340 ◽

Cited By ~ 1

Author(s):

Bruce A. Joyce ◽

Michael J. Stowell

Keyword(s):

Thin Films ◽

Electron Microscope ◽

Electron Diffraction ◽

Film Growth ◽

Epitaxial Thin Films ◽

Disorder Effects ◽

Transmission Electron ◽

Innovative Materials ◽

Low Dimensional

Donald William (Don) Pashley was one of the most innovative materials scientists of his generation. He was distinguished for his electron diffraction and transmission electron microscope studies of epitaxial thin films, especially for in situ investigations, work that contributed enormously to our understanding of film growth processes. He pioneered the use of moiré patterns to reveal dislocations and other defects. He also made important contributions to long-range disorder effects on semiconductor surfaces and to the structure of low-dimensional semiconductor systems.

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Crystallization of Epitaxial Lanthanum Aluminate and Spinel Thin Films Derived from Nitrate Precursors

MRS Proceedings ◽

10.1557/proc-341-145 ◽

1994 ◽

Vol 341 ◽

Cited By ~ 2

Author(s):

Man Fai Ng ◽

Michael J. Cima

Keyword(s):

Thin Films ◽

Epitaxial Film ◽

Amorphous Film ◽

Zero Field ◽

Epitaxial Thin Films ◽

Lanthanum Aluminate ◽

Initial Nucleation ◽

Metalorganic Deposition ◽

Current Densities ◽

Higher Temperature

AbstractBoth lanthanum aluminate (LaAIO 3) and spinel (MgAl2O 4) epitaxial thin films have been deposited on either planar and stepped (100) SrTiO3 single crystal substrates by pyrolysis of mixed nitrate precursors. The precursors pyrolyze initially into amorphous films. Nucleation of lanthanum aluminate and spinel occurs at the filnVsubstrate interface at higher temperature. Crystallization of LaAlO3 on SrTiO3 substrates occurs at approximately 650°C, whereas nucleation occurs at approximately 800'C without lattice-matched substrates. Similarly, latticematched substrates reduce the crystallization temperature of spinel to below 700°C. The epitaxial film grows at the expense of the amorphous film after the initial nucleation at the interface. The rapid growth and volume change due to the crystallization leave behind an epitaxial film with nanoporosity of 15 to 30 nm. Nevertheless, the surfaces of these films have roughness of only 6–9 Å. Ba2Ycu3O7-x films derived from metalorganic deposition of metal trifluoroacetate precursors was deposited on these epitaxial LaAlO3 films on both planar and stepped SrTiO3 substrates. The resultant YBCO films on LaAlO3 film on planar SrTiO3 substrate have critical current densities of > 2 × 106 A/cm2 at 77K and zero field.

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