Maskless Lateral Epitaxial Overgrowth of GaN on Sapphire

1999 ◽  
Vol 572 ◽  
Author(s):  
P. Fini ◽  
H. Marchand ◽  
J. P. Ibbetson ◽  
B. Moran ◽  
L. Zhao ◽  
...  
Keyword(s):  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Defect Reduction ◽  
Lateral Epitaxial Overgrowth ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Crystallographic Tilt

ABSTRACTWe demonstrate a technique of lateral epitaxial overgrowth (LEO) of GaN, termed 'maskless' LEO, in which no mask is deposited prior to LEO regrowth. Instead, a bulk (> 2 μm) GaN layer on sapphire is selectively dry etched, leaving ∼5 μm-wide stripe mesas oriented in the <1010>GaN direction, with a 20 μm period. These stripes serve as seeds for LEO GaN growth, which proceeds from the tops of the stripes and expands laterally, resulting in a ‘T’, or overhang, morphology. As for LEO over an SiO2 mask, significant defect reduction (from ∼109 cm−2 to ∼106 cm−2 ) is observed in cross-sectional transmission electron microscopy (TEM). Atomic force microscopy of the top surface of the LEO GaN reveals that no threading dislocations with screw component terminate at the surfaces of laterally overgrown regions. X-ray diffraction measurements reveal that the wings exhibit a crystallographic tilt away from the seed regions in an azimuth perpendicular to the stripe direction; the tilt angle (∼0.4 – 0.5°) is relatively independent of growth temperature and wing aspect ratio.

Epitaxial BaTiO3 Thin Films on Different Substrates for Optical Waveguide Applications

1999 ◽  
Vol 597 ◽  
Author(s):  
M. Siegert ◽  
Judit G. Lisoni ◽  
C. H. Lei ◽  
A. Eckau ◽  
W. Zander ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Waveguides ◽  
Rutherford Backscattering Spectrometry ◽  
Optical Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Ion Channeling ◽  
Atomic Force ◽  
Transmission Electron

AbstractIn the process of developing thin film electro-optical waveguides we investigated the influence of different substrates on the optical and structural properties of epitaxial BaTiO3 thin films. These films are grown by on-axis pulsed laser deposition (PLD) on MgO(100), MgAl2O4(100), SrTiO3(100) and MgO buffered A12O3(1102) substrates. The waveguide losses and the refractive indices were measured with a prism coupling setup. The optical data are correlated to the results of Rutherford backscattering spectrometry/ion channeling (RBS/C). X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). BaTiO3 films on MgO(100) substrates show planar waveguide losses of 3 dB/cm and ridge waveguide losses of 5 dB/cm at a wavelength of 633 nm.

Analysis of Sn Behavior During Ni/GeSn Solid-State Reaction by Correlated X-ray Diffraction, Atomic Force Microscopy, and Ex-situ/In-situ Transmission Electron Microscopy

2020 ◽  
Vol 98 (5) ◽  
pp. 365-375
Author(s):  
Andrea Quintero ◽  
Patrice Gergaud ◽  
Jean-Michel Hartmann ◽  
Vincent Delaye ◽  
Nicolas Bernier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

(G03 Best Paper Award Winner) Analysis of Sn Behavior During Ni/GeSn Solid-State Reaction by Correlated X-ray Diffraction, Atomic Force Microscopy, and Ex-situ/In-situ Transmission Electron Microscopy

2020 ◽  
Vol MA2020-02 (24) ◽  
pp. 1750-1750
Author(s):  
Andrea Quintero Colmenares ◽  
Patrice Gergaud ◽  
Jean-Michel Hartmann ◽  
Vincent Delaye ◽  
Nicolas Bernier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ex Situ ◽  
Paper Award ◽  
X Ray Diffraction ◽  
Award Winner ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Evaluation of the Strain Field Inside and Around Growth Islands by Means of X-Ray Diffuse Scattering

1999 ◽  
Vol 583 ◽  
Author(s):  
Martin Schmidbauer ◽  
Thomas Wiebach ◽  
Helmut Raidt ◽  
Peter Schäfer ◽  
Michael hanke ◽  
...  
Keyword(s):  
Strain Field ◽  
Reciprocal Space ◽  
X Ray Diffraction ◽  
Abrupt Increase ◽  
X Ray ◽  
Force Microscopy ◽  
Self Organized ◽  
Atomic Force ◽  
Transmission Electron ◽  
Highly Strained

AbstractThe strain distribution inside and in the vicinity of coherently strained self-organized islands has been investigated by high-resolution x-ray diffraction (HRXRD). Finite element method (FEM) calculations were carried out in order to calculate the strain field, which was then used to simulate x-ray reciprocal space maps on the basis of kinematical scattering theory. For Si0 75Ge0.25 islands an abrupt increase in the Ge-concentration at about one third of the island height has been found. This behavior can be attributed to different nucleation stages during growth. Highly strained buried CdSe quantum dots (QDs) strongly influence the surrounding ZnSe matrix. From reciprocal space maps and FEM simulations we were able to estimate the shape and size of the islands. The results are in agreement with transmission electron microscopy (TEM) and UHV atomic force microscopy (AFM) data.

scholarly journals Effects of Size and Dispersity of Microcrystalline Celluloses on Size, Structure and Stability of Nanocrystalline Celluloses Extracted by Acid Hydrolysis

Nano LIFE ◽  
2014 ◽  
Vol 04 (04) ◽  
pp. 1441014 ◽  
Author(s):  
Qi Liu ◽  
Weiping Hao ◽  
Yongguang Yang ◽  
Aurore Richel ◽  
Canbin Ouyang ◽  
...  
Keyword(s):  
Particle Size ◽  
Acid Hydrolysis ◽  
Size Structure ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Sonication Treatment

Nanocrystalline celluloses (NCCs) were separated from four commercial microcrystalline celluloses (MCCs) by an acid hydrolysis–sonication treatment. Transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were conducted to investigate the NCCs. MCCs with different morphologies and particle sizes showed different aggregation degrees. The aggregation of MCCs followed the order MCC1 > MCC3 > MCC2 > MCC4, which is the same order of the heights of the resulting NCCs. The best uniformity and thermal stability were characterized for NCC3, which was produced by MCC3 with smallest original particle size and good dispersity among the four MCCs. This result suggests that both the original particle size and dispersity of MCCs had significant effects on separated NCCs.

scholarly journals Structural Property Study for GeSn Thin Films

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3645
Author(s):  
Liyao Zhang ◽  
Yuxin Song ◽  
Nils von den Driesch ◽  
Zhenpu Zhang ◽  
Dan Buca ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) and on Ge-buffered Si (001) wafers by chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction and cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection were collected by X-ray diffraction for both the whole structures and the GeSn epilayers. The broadenings of the features of the GeSn epilayers with different relaxations in the ω direction, along the ω-2θ direction and parallel to the surface were investigated. The dislocations were identified by transmission electron microscopy. Threading dislocations were found in MBE grown GeSn layers, but not in the CVD grown ones. The point defects and dislocations were two possible reasons for the poor optical properties in the GeSn alloys grown by MBE.

A Model for the Films Formation of Nb–Si–N Ternary Compound Deposited

2012 ◽  
Vol 476-478 ◽  
pp. 475-479 ◽  
Author(s):  
Yong Jun Jiang
Keyword(s):  
Film Formation ◽  
Composite Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanoscale Structures ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Step Model ◽  
Si Content

By means of the reactive magnetron sputtering method, a series of Nb–Si–N composite films with different Si contents were deposited in an Ar, N2 and SiH4 mixture atmosphere. These films’ chemical composition, phase formation, microstructure and mechanical properties were characterized by the energy dispersive spectroscopy, X-ray diffraction, transmission electron microcopy, atomic force microscopy and nanoindentation. In the Nb–Si–N films, 3 distinct concentration regions have been observed depending on the Si content. Based on the three concentration regions, a three-step model is proposed for the film formation of the Nb–Si–N thin films. This model correlates nanoscale structures with macroscopic properties of the films.

scholarly journals Ultrashort Pulsed Laser Ablation of Magnesium Diboride: Plasma Characterization and Thin Films Deposition

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Angela De Bonis ◽  
Agostino Galasso ◽  
Antonio Santagata ◽  
Roberto Teghil
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Optical Emission ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Laser Target ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

A MgB2target has been ablated by Nd:glass laser with a pulse duration of 250 fs. The plasma produced by the laser-target interaction, showing two temporal separated emissions, has been characterized by time and space resolved optical emission spectroscopy and ICCD fast imaging. The films, deposited on silicon substrates and formed by the coalescence of particles with nanometric size, have been analyzed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. The first steps of the films growth have been studied by Transmission Electron Microscopy. The films deposition has been studied by varying the substrate temperature from 25 to 500°C and the best results have been obtained at room temperature.

Optical And Structural properties of Vertical Aligned Self-Assembled InAs Quantum Dots Multilayers

2001 ◽  
Vol 676 ◽  
Author(s):  
J. C. González ◽  
M. I. N. da Silva ◽  
W. N. Rodrigues ◽  
F. M. Matinaga ◽  
R. Magalhaes-Paniago ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Structural Properties ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Self Assembled

ABSTRACTIn this work, we report optical and structural properties of vertical aligned self-assembled InAs quantum dots multilayers. The InAs quantum dots samples were grown by Molecular Beam Epitaxy. Employing Atomic Force Microscopy, Transmission Electron Microscopy, and Gracing Incident X-ray Diffraction we have studied the structural properties of samples with different number of periods of the multiplayer structure, as well as different InAs coverage. The optical properties were studied using Photoluminescence spectroscopy.

Epitaxial growth of PbTiO3 thin films on (001) SrTiO3 from solution precursors

1995 ◽  
Vol 10 (3) ◽  
pp. 680-691 ◽  
Author(s):  
Andreas Seifert ◽  
Fred F. Lange ◽  
James S. Speck
Keyword(s):  
Thin Films ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Amorphous Precursor ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Heat Treated ◽  
Film Substrate

A mixed alkoxide liquid precursor was used to form epitaxial PbTiO3 thin films by spin-coating on cubic (001) SrTiO3 substrates. The films were heat-treated at temperatures between 380 °C/1 h and 800 °C/1 h. X-ray diffraction, atomic force microscopy, scanning and transmission electron microscopy were used to characterize the microstructure of the films and to evaluate the epitaxial phenomena. At ∼400 °C/1 h, a polycrystalline, metastable Pb-Ti fluorite crystallizes from the pyrolyzed amorphous precursor. At slightly higher temperatures (∼420 °C/1 h), the thermodynamically stable phase with the perovskite structure epitaxially nucleates at the film/substrate interface. A small number of epitaxial grains grow through the film toward the surface and consume the nanocrystalline fluorite grains. Coarsening of the perovskite grains leads to a reduction in mosaic spread during further heating. Pores, which concurrently coarsen with grain growth, produce a pitted surface as they disappear from within the film. At 800 °C/1 ha dense epitaxial PbTiO3 film with a smooth surface is observed. Parameters governing the formation of a- and c-domains are discussed as well as the small tilts of the domain axes away from the substrate normal.

Sign in / Sign up

Export Citation Format

Share Document