Surface and Interface Damage Characterization of Reactive Ion Etched MBE Regrown GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
M.W. Cole ◽  
M. Dutta ◽  
J. Rossabi ◽  
D.D. Smith ◽  
J.L. Lehman
Keyword(s):  
Raman Spectroscopy ◽  
Structural Damage ◽  
Crystal Defects ◽  
Interface Roughness ◽  
Surface And Interface ◽  
Transmission Electron ◽  
Microstructural Evaluation ◽  
Wet Chemical ◽  
Power Densities

AbstractDamage resulting from reactive ion etching (RIE) and wet etching of MBE grown GaAs and the defects generated in subsequent GaAs regrowth was evaluated by Transmission Electron Microscopy (TEM), photoluminescence (PL) , and Raman spectroscopy. The samples were reactively etched with HCl and Cl2 at two power densities; 0.3 W/cm2 and 0.6 W/cm2. A wet chemical (H2O:H3PO4:H2O2) etched sample was used for comparison. The LO phonon intensities measured by room temperature Raman spectroscopy showed a strong correlation to the relative PL intensities, where the HCl sample was found to be inferior to the others. TEM microstructural evaluation showed both HCl RIE samples to have significant interface roughness, with the sample etched at 0.6 W/cm2 showing the most structural damage in the regrowth region. Defect densities for the Cl2. and wet etched samples were two orders of magnitude lower than that of the HCl etched samples. The extent of disorder in the regrowth region was largest for the HCl sample with respect to the Cl2 and wet etched samples. These microstructural and optical results suggest that the H+ ion plays an important role in the generation of crystal defects during the RIE process.

scholarly journals Characterization of ferrite nanoparticles for preparation of biocomposites

2017 ◽  
Vol 8 ◽  
pp. 1257-1265 ◽  
Author(s):  
Urszula Klekotka ◽  
Magdalena Rogowska ◽  
Dariusz Satuła ◽  
Beata Kalska-Szostko
Keyword(s):  
Chemical Method ◽  
Ferrite Nanoparticles ◽  
Chemical Activity ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

Ferrite nanoparticles with nominal composition Me0.5Fe2.5O4 (Me = Co, Fe, Ni or Mn) have been successfully prepared by the wet chemical method. The obtained particles have a mean diameter of 11–16 ± 2 nm and were modified to improve their magnetic properties and chemical activity. The surface of the pristine nanoparticles was functionalized afterwards with –COOH and –NH2 groups to obtain a bioactive layer. To achieve our goal, two different modification approaches were realized. In the first one, glutaraldehyde was attached to the nanoparticles as a linker. In the second one, direct bonding of such nanoparticles with a bioparticle was studied. In subsequent steps, the nanoparticles were immobilized with enzymes such as albumin, glucose oxidase, lipase and trypsin as a test bioparticles. The characterization of the nanoparticles was acheived by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and Mössbauer spectroscopy. The effect of the obtained biocomposites was monitored by Fourier transform infrared spectroscopy. The obtained results show that in some cases the use of glutaraldehyde was crucial (albumin).

Synthesis and Characterization of Calcium Tartrate Dihydrate Nanoparticles

2015 ◽  
Vol 14 (04) ◽  
pp. 1550013 ◽  
Author(s):  
Urvisha Tarpara ◽  
Poorvesh Vyas ◽  
Mihir J. Joshi
Keyword(s):  
Average Crystallite Size ◽  
Powder Xrd ◽  
Xrd Pattern ◽  
Crystalline Materials ◽  
Transmission Electron ◽  
Calcium Tartrate ◽  
Particle Size And Morphology ◽  
Wet Chemical ◽  
Size And Morphology

Calcium tartrate finds various applications. In the present study, calcium tartrate nanoparticles were synthesized by wet chemical method using surfactant mediated approach. The powder XRD pattern revealed the typical broadening of peaks indicating the nanostructured nature. The average crystallite size was calculated by applying the Scherrer's formula to powder XRD pattern and was found in the range of 22.8–23.9 nm. The particle size and morphology of the synthesized nanoparticles was confirmed by using transmission electron microscopy (TEM). FTIR spectroscopy was used to confirm the presence of various functional groups. From TGA, it was found that calcium tartrate nanoparticles remained stable up to 120°C and were having two water molecules associated with them. The results are compared with the bulk crystalline materials available in the literature.

Surface and Interface Characterization of Ion Beam Re-crystallized Si

2002 ◽  
Vol 750 ◽  
Author(s):  
P. K. Sahoo ◽  
B. Satpati ◽  
S. Dey ◽  
P. V. Satyam ◽  
T. Som ◽  
...  
Keyword(s):  
Ion Beam ◽  
Amorphous Layer ◽  
Amorphous Structure ◽  
Average Height ◽  
Force Microscopy ◽  
Surface And Interface ◽  
Atomic Force ◽  
Nano Crystalline ◽  
Transmission Electron

ABSTRACTIn the present work we have studied efficacy of ion beam induced epitaxial crystallization (IBIEC) to recover amorphous layers (300 – 350 nm) produced by MeV Kr ions in Si(100) and studied the associated changes occurring on surface and interface of the recrystallized region. IBIEC experiments were carried out at sample temperatures in the range of 200 − 400°C using 1 MeV N+ ion beam. Rutherford backscattering-Channeling technique showed planar and gradual recovery of the amorphous layer as a function of temperature. Transmission electron microscopy measurements show good crystalline structure of the recovered region at 400°C while at lower temperatures nano-crystalline Si formation embedded in the amorphous structure is evident. The surface topography studied by atomic force microscopy shows development of islands after IBIEC. The rms roughness is around 0.5 nm and average height of the islands is found to be 1.8 nm. The observed epitaxial growth and the surface topographical features have been correlated.

Microstructure and Properties of Nanosemicrystalline Si3N4 Ceramics with Doped Sintering Additives: Part I. Microstructural Characterization of Nanosemicrystalline Si3N4 Powders

1998 ◽  
Vol 13 (9) ◽  
pp. 2580-2587 ◽  
Author(s):  
K. H. Ryu ◽  
J-M. Yang
Keyword(s):  
Microstructural Characterization ◽  
Degree Of Crystallinity ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Additives ◽  
Transmission Electron ◽  
Wet Chemical ◽  
Si3n4 Ceramics

The characteristics of nanosized silicon nitride powders with doped Y2O3 and Al2O3 fabricated by a plasma-reacted chemical process were investigated. The chemical compositions of the powders were analyzed by wet chemical analysis. The morphology and the size distribution were determined by transmission electron microscopy (TEM). TEM with energy dispersive spectroscopy (EDS) was used to verify the existence of sintering additives in each individual particle. The crystal structure of the powders was identified by the selected area diffraction pattern (SADP). X-ray diffraction (XRD) technique was used for phase analysis and the measurement of degree of crystallinity. The characteristics of chemical bonding was analyzed by using Fourier transform infrared spectroscopy (FTIR).

Study and characterization of the carbon-based nanoparticles obtained from PET

2013 ◽  
Vol 1549 ◽  
pp. 149-154
Author(s):  
Alena Borisovna Kharissova ◽  
Edgar de Casas Ortiz ◽  
Oxana V. Kharissova ◽  
Ubaldo Ortiz Mendez ◽  
Boris I. Kharisov
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Normal Pressure ◽  
Transmission Electron ◽  
Polymer Type ◽  
Scanning Electron ◽  
Carbon Based

ABSTRACTMaterial like PET {polyethylene terephthalate (C10H8O4)n} are usually thrown away present in glasses of refreshments, water bottles between others which are hard to be degraded. However, this material can be recycled and used to acquire nanostructures. During this investigation the objective was to obtain nanoparticles and carbon based nanostructures from the polymer type PET by means of microwave irradiation at the temperature of 260°C at normal pressure and at 600 psi in the presence of acids, ethylene glycol and by means of calcinations. The obtained nanoparticles of ultrananocrystalline diamonds were studied by means of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and Raman spectroscopy.

scholarly journals Characterization of MXene as a Cancer Photothermal Agent Under Physiological Conditions

2021 ◽  
Vol 3 ◽  
Author(s):  
Samar Shurbaji ◽  
Nimshitha P. Abdul Manaph ◽  
Samia M. Ltaief ◽  
Abeer R. Al-Shammari ◽  
Ahmed Elzatahry ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Shear Stress ◽  
Cancer Cells ◽  
Fluid Shear Stress ◽  
Energy Dispersive Spectrometer ◽  
Physiological Conditions ◽  
Viability Assay ◽  
Transmission Electron ◽  
Power Densities

A growing interest has recently emerged in the use of nanomaterials in medical applications. Nanomaterials, such as MXene, have unique properties due to their 2D ultra-thin structure, which is potentially useful in cancer photothermal therapy. To be most effective, photothermal agents need to be internalized by the cancer cells. In this study, MXene was fabricated using chemical reactions and tested as a photothermal agent on MDA-231 breast cancer cells under static and physiological conditions. Fluid shear stress (∼0.1 Dyn/cm2) was applied using a perfusion system to mimic the physiological tumor microenvironment. The uptake of MXene was analyzed under fluid flow compared to static culture using confocal microscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM). Furthermore, a viability assay was used to assess cell’s survival after exposing the treated cells to photothermal laser at different power densities and durations. We showed that when incubated with cancer cells, 2D MXene nanoparticles were successfully internalized into the cells resulting in increased intracellular temperatures when exposed to NIR laser. Interestingly, dynamic culture alone did not result in a significant increase in uptake suggesting the need for surface modifications for enhanced cellular uptake under shear stress.

Structural Characterization of Nc-Si/A-Sio2 Superlattices Subjected To Thermal Treatment

1998 ◽  
Vol 536 ◽  
Author(s):  
G. F. Grom ◽  
L. Tsybeskov ◽  
K. D. Hirschman ◽  
P. M. Fauchet ◽  
J. P. McCaffrey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Defect Density ◽  
High Temperature Annealing ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Si Nanocrystals

AbstractThe morphology of nanocrystalline (nc)-Si/amorphous (a)-SiO2 superlattices (SLs) is studied using Raman spectroscopy in the acoustic and optical phonon ranges, transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is demonstrated that high temperature annealing (up to 1100°C) and oxidation in O2/H2O ambient do not destroy the SL structure, which retains its original periodicity and nc-Si/a-SiO2 interface abruptness. It is found that oxidation at high temperatures reduces the defect density in nc-Si/a-SiO2 SLs and induces the lateral coalescence of Si nanocrystals (NCs). The size, shape, packing density, and crystallographic orientation of the Si nanocrystals are studied as a function of the oxidation time.

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