Characterization and Manipulation of Exposed Ge Nanocrystals

2004 ◽  
Vol 818 ◽  
Author(s):  
I.D. Sharp ◽  
Q. Xu ◽  
C.Y. Liao ◽  
D.O. Yi ◽  
J.W. Ager ◽  
...  
Keyword(s):  
Hydrofluoric Acid ◽  
Metal Films ◽  
Silica Matrix ◽  
Size Distributions ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Oxide Matrix ◽  
Ge Nanocrystals

AbstractIsotopically pure 70Ge and 74Ge nanocrystals embedded in SiO2 thin films on Si substrates have been fabricated through ion implantation and thermal annealing. Nanocrystals were subsequently exposed using a hydrofluoric acid etching procedure to selectively remove the oxide matrix while retaining up to 69% of the implanted Ge. Comparison of transmission electron micrographs (TEM) of as-grown crystals to atomic force microscope (AFM) data of exposed crystals reveals that the nanocrystal size distribution is very nearly preserved during etching. Therefore, this process provides a new means to use AFM for rapid and straightforward determination of size distributions of nanocrystals formed in a silica matrix. Once exposed, nanocrystals may be transferred to a variety of substrates, such as conducting metal films and optically transparent insulators for further characterization.

Development of Ge Nanoparticles Embedded in GeO2 Matrix

2008 ◽  
Vol 8 (8) ◽  
pp. 4081-4085 ◽  
Author(s):  
Y. Batra ◽  
D. Kabiraj ◽  
D. Kanjilal
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Spectroscopic Studies ◽  
Electron Beam Evaporation ◽  
Granular Structure ◽  
Raman Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Ge Nanocrystals

Germanium (Ge) nanoparticles have attracted a lot of attention due to their excellent optical properties. In this paper, we report on the formation of Ge nanoparticles embedded in GeO2 matrix prepared by electron beam evaporation and subsequent annealing. Transmission electron microscopy (TEM) studies clearly indicate the formation of Ge nanocrystals in the films annealed at 500 °C. Fourier transform infrared (FTIR) spectroscopic studies are carried out to verify the evolution of the structure after annealingat each stage. Micro-Raman analysis also confirms the formation of Ge nanoparticles in the annealed films. Development of Ge nanoparticles is also established by photoluminescence (PL) analysis. Surface morphology study is carried out by atomic force microscopy (AFM). It shows the evolution of granular structure of the films with increasing annealing temperature.

Formation of Sub-100 NM GE Wires on Si by E-Beam Evaporation/Lithography

1995 ◽  
Vol 380 ◽  
Author(s):  
C. Deng ◽  
J. C. Wu ◽  
C. J. Barbero ◽  
T. W. Sigmon ◽  
M. N. Wybourne
Keyword(s):  
Cross Section ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Si Substrates ◽  
Novel Technique ◽  
Atomic Force ◽  
Transmission Electron ◽  
First Time ◽  
Scanning Electron

ABSTRACTA fabrication process for sub-100 nm Ge wires on Si substrates is reported for the first time. Wires with a cross section of 6 × 57 nm2 are demonstrated. The wire structures are analyzed by atomic force (AFM), scanning electron (SEM), and transmission electron microscopy (TEM). Sample preparation for TEM is performed using a novel technique using both pre and in situ deposition of multiple protection layers using a Focused Ion Beam (FIB) micromachining system.

Ion Beam Synthesis of Luminescent SI and GE Nanocrystals in a Silicon Dioxide Matrix

1993 ◽  
Vol 316 ◽  
Author(s):  
H.A. Atwater ◽  
K.V. Shcheglov ◽  
S.S. Wong ◽  
K.J. Vahala ◽  
R.C. Flagan ◽  
...  
Keyword(s):  
Ion Beam ◽  
Optoelectronic Device ◽  
Structural Defects ◽  
Si Substrates ◽  
Localized State ◽  
Transmission Electron ◽  
Ion Beam Synthesis ◽  
Theoretical Predictions ◽  
Device Applications ◽  
Ge Nanocrystals

ABSTRACTIon beam synthesis of Si and Ge nanocrystals in an SiO2 matrix is performed by precipitation from supersaturated solid solutions created by ion implantation. Films of SiO2 on (100) Si substrates are implanted with Si and Ge at doses 1 × 1016/cm2 - 5 × 1016/cm2. Implanted samples are subsequently annealed to induce precipitation of Si and Ge nanocrystals. Raman spectroscopy and high-resolution transmission electron microscopy indicate a correlation between visible room-temperature photoluminescence and the formation of diamond cubic nanocrystals approximately 2–5 nm in diameter in annealed samples. As-implanted but unannealed samples do not exhibit luminescence. Rutherford backscattering spectra indicate a steepening of implanted Ge profiles upon annealing. Photoluminescence spectra are correlated with annealing temperatures, and compared with theoretical predictions for various possible luminescence mechanisms, such as radiative recombination of quantum-confined excitons, as well as possible localized state luminescence related to structural defects in SiO2. Potential optoelectronic device applications are also discussed.

Nanomechanical Properties and Nanostructure of CMG and CMP Machined Si Substrates

2008 ◽  
Vol 381-382 ◽  
pp. 525-528 ◽  
Author(s):  
B.L. Wang ◽  
Han Huang ◽  
Jin Zou ◽  
Li Bo Zhou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Substrate Surface ◽  
Transmission Electron Microscopy Analysis ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Electron Microscopy Analysis

Silicon (100) substrates machined by chemo-mechanical-grinding (CMG) and chemicalmechanical- polishing (CMP) were investigated using atomic force microscopy, cross-sectional transmission electron microscopy and nanoindentation. It was found that the substrate surface after CMG was slightly better than machined by CMP in terms of roughness. The transmission electron microscopy analysis showed that the CMG-generated subsurface was defect-free, but the CMP specimen had a crystalline layer of about 4 nm in thickness on the top of the silicon lattice as evidenced by the extra diffraction spots. Nanoindentation results indicated that there exists a slight difference in mechanical properties between the CMG and CMP machined substrates.

RBS, XRD, Raman and AFM Studies of Microwave Synthesized Ge Nanocrystals

2011 ◽  
Vol 1354 ◽  
Author(s):  
N Srinivasa Rao ◽  
A P Pathak ◽  
G Devaraju ◽  
V Saikiran ◽  
S V S Nageswara Rao
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Rf Magnetron Sputtering ◽  
Silica Matrix ◽  
Raman Spectrometry ◽  
Force Microscopy ◽  
Microwave Annealing ◽  
Atomic Force ◽  
Scattering Spectra ◽  
Raman Scattering Spectra ◽  
Ge Nanocrystals

ABSTRACTGe nanocrystals embedded in silica matrix have been synthesized on Si substrate by co-sputtering of SiO2 and Ge using RF magnetron sputtering technique. The as-deposited films were subjected to microwave annealing at 800 and 9000C. Rutherford backscattering spectrometry (RBS) has been used to measure the Ge composition and film thickness. The structural characterization was performed by using X-ray diffraction (XRD) and Raman spectrometry. XRD measurements confirmed the formation of Ge nanocrystals. Raman scattering spectra showed a peak of Ge-Ge vibrational mode around 299 cm−1, which was caused by quantum confinement of phonons in the Ge nanocrystals. Surface morphology of the samples was studied by atomic force microscopy (AFM). Variation of nanocrystal size with annealing temperature has been discussed. Advantages of microwave annealing are explained in detail.

Surface Morphology of SiGe Epitaxial Layers Grown on Uniquely Oriented Si Substrates

2000 ◽  
Vol 648 ◽  
Author(s):  
Morgan E. Ware ◽  
Robert J. Nemanich
Keyword(s):  
Surface Morphology ◽  
Lattice Mismatch ◽  
Morphological Structure ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Relationship Of

AbstractThe 4% lattice mismatch between Si and Ge creates strain in epitaxial layers of SiGe alloys on Si, and this strain can manifest itself in the morphological structure of the surface of the epitaxial layer. This study explores the relationship of the evolution of the surface morphology of SiGe layers grown on a range of Si surface orientations. We have grown thin, strained and thick, relaxed layers of Si0.7Ge0.3 by solid source molecular beam epitaxy on substrates with surface normals rotated from [001] towards [111] by angles of θ = (0, 2, 4, 10, 22) degrees. The surface morphology was investigated by atomic force microscopy, which showed considerable ordering of surface features on relaxed samples. These features evolve from hut-like structures at 0 degrees to large mesa-like structures separated by pits and crevices at 22 degrees. The organization of these features is also shown to vary with the substrate orientation. Each surface has characteristic directions along which features are aligned, and these directions vary continuously with the angle of rotation of the substrate. Transmission electron microscopy confirmed that misfit dislocations had formed along those same directions. The state of relaxation of each layer is quantified by Raman spectroscopy in order to make a direct correlation between residual strain and surface morphology.

Comparative Studies of Pb/Cu(001) by TEM, AFM and STM

1998 ◽  
Vol 528 ◽  
Author(s):  
Franck Bocquet ◽  
Camille Cohen ◽  
Didier Schmaus ◽  
André Rocher ◽  
Jacques Crestou ◽  
...  
Keyword(s):  
Accurate Determination ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Specific Orientation

AbstractThe same specimen of Pb/Cu grown under Ultra High Vacuum (UHV) conditions has been investigated by Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). We show that the information obtained by these techniques is consistent when comparable, and complementary. In particular, three different morphologies of Pb islands with specific orientation relationship are observed; AFM reveals the faceted shape of the islands; STM permits an accurate determination of the atomic structure of the facets; TEM moir6 patterns reveal that Pb islands are well relaxed.

3C-SiC Heteroepitaxy on (100), (111) and (110) Si Using Trichlorosilane (TCS) as the Silicon Precursor.

2008 ◽  
Vol 600-603 ◽  
pp. 243-246 ◽  
Author(s):  
Ruggero Anzalone ◽  
Andrea Severino ◽  
Giuseppe D'Arrigo ◽  
Corrado Bongiorno ◽  
Patrick Fiorenza ◽  
...  
Keyword(s):  
Growth Process ◽  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
Tem Analysis ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
The Impact

The aim of this work is to improve the heteroepitaxial growth process of 3C-SiC on Si substrates using Trichlorosilane (SiHCl3) as the silicon growth precursor. With this precursor it has been shown that it is possible to simultaneously increase the growth rate of the process and avoid the nucleation of silicon droplets in the gas phase. Growth experiments were conducted on three (3) Si substrate orientations in order to assess the impact of the Si substrate on the resulting 3C-SiC film. X-ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) analysis show the important role of the substrate orientation for the growth process. The different orientation of the substrate modifies the morphology of the 3C-SiC crystalline structure, mostly by changing the density of micro-twins and stacking faults inside the film.

scholarly journals Liberation of Ion Implanted Ge Nanocrystals from a Silicon Dioxide Matrix via Hydrofluoric Acid Vapor Etching

2003 ◽  
Vol 777 ◽  
Author(s):  
I.D. Sharp ◽  
Q. Xua ◽  
C. Y. Liao ◽  
J.W. Ager ◽  
J.W. Beeman ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Raman Spectra ◽  
Hydrofluoric Acid ◽  
Peak Frequency ◽  
Atmospheric Conditions ◽  
Phonon Confinement ◽  
Acid Vapor ◽  
Si Substrates ◽  
Wide Range ◽  
Ge Nanocrystals

AbstractA method to liberate germanium (Ge) nanocrystals from silicon dioxide (SiO2) thin films by hydrofluoric acid (HF) vapor etching is presented. Multi-energy implantation of mass separated Ge ions into 500-nm-thick wet oxide layers on silicon (Si) substrates followed by thermal annealing produces nanocrystals that are 2 to 8 nm in diameter. Raman spectra exhibit the expected asymmetric line shapes due to the phonon confinement effect, but with a higher peak frequency than predicted. To free the nanocrystals, samples are etched in HF vapor to selectively remove the SiO2 matrix and expose the nanocrystal surfaces. Raman spectra of etched samples display peak frequencies consistent with relief of compressive stress. The liberated nanocrystals show long-term stability under ambient atmospheric conditions. Ge nanocrystals can be removed from etched surfaces using an ultrasonic methanol cleaning procedure. The nanocrystal-containing solution is applied to a TEM grid and the solvent is evaporated. Subsequently obtained electron diffraction patterns confirm that the nanocrystals survive this transfer step. Thus, liberated Ge nanocrystals are expected to be accessible for a wide range of manipulation processes and direct characterization techniques.

Formation of Ge Nanocrystals in SiO2 by Electron Beam Evaporation

2008 ◽  
Vol 8 (2) ◽  
pp. 818-822 ◽  
Author(s):  
P. Basa ◽  
G. Molnár ◽  
L. Dobos ◽  
B. Pécz ◽  
L. Tóth ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Sheet Resistance ◽  
Electron Beam Evaporation ◽  
Nanocrystal Size ◽  
Cross Sectional ◽  
Si Substrates ◽  
Transmission Electron ◽  
Weber Type ◽  
Ge Nanocrystals

Ge nanocrystals were formed by electron beam evaporation on SiO2 covered Si substrates. The size and distribution of the nanocrystals were studied by atomic force microscopy, scanning electron microscopy and cross-sectional transmission electron microscopy. Dependencies of the nanocrystal size, of the nanocrystal surface coverage, and sheet resistance obtained by van der Pauw method of the Ge layer have been found on the evaporation time. The suggested growth mechanism for the formation of nanocrystals is the Volmer-Weber type. The sheet resistance exhibited a power dependence on the nanocrystal size.

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