On The Optimized Nucleation of Near-Single-Crystal Cvd Diamond Film

1995 ◽  
Vol 416 ◽  
Author(s):  
L. C. Chen ◽  
C. C. Juan ◽  
J. Y. Wu ◽  
K. H. Chen ◽  
J. W. Teng
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Morphological Evolution ◽  
Present Report ◽  
Ex Situ ◽  
Nucleation Density ◽  
Induced Current ◽  
Current Time ◽  
Single Crystal Diamond

ABSTRACTNear-single-crystal diamond films have been obtained in a number of laboratories recently. The optimization of nucleation density by using a bias-enhanced nucleation (BEN) method is believed to be a critical step. However, the condition of optimized nucleation has never been clearly delineated. In the present report, a novel quantitative technique was established to monitor the nucleation of diamond in-situ. Specifically, the induced current was measured as a function of nucleation time during BEN. The timedependence of induced current was studied under various methane concentrations as well as substrate temperatures. The optimized nucleation condition can be unambiguously determined from the current-time plot. Besides the in-situ current probe, ex-situ x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were also used to investigate the chemical and morphological evolution. Characteristic XPS and AFM features of optimized nucleation is discussed.

Ion Beam Study of Early Stages of Growth of GaN films on Sapphire

2002 ◽  
Vol 743 ◽  
Author(s):  
Eugen M. Trifan ◽  
David C. Ingram
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ion Beam ◽  
Ex Situ ◽  
Crystallographic Axis ◽  
In Situ Characterization ◽  
X Ray ◽  
Ion Channeling ◽  
Stages Of Growth ◽  
Early Stages

ABSTRACTAn innovative approach for in-situ characterization has been used in this work to investigate the composition, growth mode, morphology and crystalline ordering of the early stages of growth of GaN films grown on sapphire by MOCVD for substrate temperatures in the range of 450°C to 1050°C. We have performed in-situ characterization by Rutherford Backscattering Spectroscopy (RBS), Ion Channeling, X-ray Photoelectron Spectroscopy (XPS), and Low Energy Electron Diffraction. Ex-situ the films have been characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and thickness profilometry. The films have been grown in an in-house designed and build MOCVD reactor that is attached by UHV lines to the analysis facilities. RBS analysis indicated that the films have the correct stoichiometry, have variable thickness and for low substrate temperature completely cover the substrate while for temperatures 850°C and higher islands are formed that may cover as few as 5 percent of the substrate. From Ion Channeling and LEED we have determined the crystallographic phase to be wurtzite. The crystalline quality increases with higher deposition temperature and with thickness. The films are epitaxialy grown with the <0001> crystallographic axis and planes of the GaN films aligned with the sapphire within 0.2 degrees.

scholarly journals In situ spectroscopic monitoring of CO2 reduction at copper oxide electrode

2017 ◽  
Vol 197 ◽  
pp. 517-532 ◽  
Author(s):  
Liying Wang ◽  
Kalyani Gupta ◽  
Josephine B. M. Goodall ◽  
Jawwad A. Darr ◽  
Katherine B. Holt
Keyword(s):  
Infrared Spectroscopy ◽  
Copper Oxide ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Modified Electrodes ◽  
Starting Material ◽  
Ex Situ ◽  
Spectroscopic Monitoring ◽  
Carbonate Species

Copper oxide modified electrodes were investigated as a function of applied electrode potential using in situ infrared spectroscopy and ex situ Raman and X-ray photoelectron spectroscopy. In deoxygenated KHCO3 electrolyte bicarbonate and carbonate species were found to adsorb to the electrode during reduction and the CuO was reduced to Cu(i) or Cu(0) species. Carbonate was incorporated into the structure and the CuO starting material was not regenerated on cycling to positive potentials. In contrast, in CO2 saturated KHCO3 solution, surface adsorption of bicarbonate and carbonate was not observed and adsorption of a carbonato-species was observed with in situ infrared spectroscopy. This species is believed to be activated, bent CO2. On cycling to negative potentials, larger reduction currents were observed in the presence of CO2; however, less of the charge could be attributed to the reduction of CuO. In the presence of CO2 CuO underwent reduction to Cu2O and potentially Cu, with no incorporation of carbonate. Under these conditions the CuO starting material could be regenerated by cycling to positive potentials.

scholarly journals Nitrogen and Silicon Defect Incorporation during Homoepitaxial CVD Diamond Growth on (111) Surfaces

2015 ◽  
Vol 1734 ◽  
Author(s):  
Samuel L. Moore ◽  
Yogesh K. Vohra
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Microwave Plasma ◽  
Nitrogen Concentration ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Diamond Growth ◽  
Defect Center ◽  
Defect Centers ◽  
Single Crystal Diamond

ABSTRACTChemical Vapor Deposited (CVD) diamond growth on (111)-diamond surfaces has received increased attention lately because of the use of N-V related centers in quantum computing as well as application of these defect centers in sensing nano-Tesla strength magnetic fields. We have carried out a detailed study of homoepitaxial diamond deposition on (111)-single crystal diamond (SCD) surfaces using a 1.2 kW microwave plasma CVD (MPCVD) system employing methane/hydrogen/nitrogen/oxygen gas phase chemistry. We have utilized Type Ib (111)-oriented single crystal diamonds as seed crystals in our study. The homoepitaxially grown diamond films were analyzed by Raman spectroscopy, Photoluminescence Spectroscopy (PL), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The nitrogen concentration in the plasma was carefully varied between 0 and 1500 ppm while a ppm level of silicon impurity is present in the plasma from the quartz bell jar. The concentration of N-V defect centers with PL zero phonon lines (ZPL) at 575nm and 637nm and the Si-defect center with a ZPL at 737nm were experimentally detected from a variation in CVD growth conditions and were quantitatively studied. Altering nitrogen and oxygen concentration in the plasma was observed to directly affect N-V and Si-defect incorporation into the (111)-oriented diamond lattice and these findings are presented.

Excimer laser cleaning, annealing, and ablation of β–SiC

1989 ◽  
Vol 4 (6) ◽  
pp. 1480-1490 ◽  
Author(s):  
Pehr E. Pehrsson ◽  
Ray Kaplan
Keyword(s):  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Carbon Surface ◽  
Laser Exposure ◽  
Electron Loss ◽  
Bulk Heating ◽  
Surface Contaminants ◽  
Excimer Laser Irradiation

The effects of ArF excimer laser irradiation on β–SiC in UHV were examined for a variety of laser intensities and pulse densities. The samples were analyzed in situ with Auger and electron loss spectroscopies, and ex situ with x-ray photoelectron spectroscopy. With progressively higher laser intensities, the SiC surface was initially cleaned of carbon and oxygen surface contaminants, and the Si–LVV Auger lineshape changed from the oxide to the carbide. Still higher laser intensities then partially reordered the surface. A carbon surface layer developed, and the C-KLL lineshape transformed from carbidic to graphitic. Finally, the surface segregated into an almost pure Si layer and an underlying carbon-rich layer, followed by ablation and pitting. Bulk heating during laser exposure may enhance reordering of sputtered or implanted material.

In-situ and ex-situ AFM imaging of μN load indents on silicate glass/alumina interfaces

1996 ◽  
Vol 54 ◽  
pp. 660-661
Author(s):  
A. V. Zagrebelny ◽  
E. T. Lilleodden ◽  
J. C. Nelson ◽  
S. Ramamurthy ◽  
C. B. Carter
Keyword(s):  
Single Crystal ◽  
Silicate Glass ◽  
Small Volume ◽  
Ex Situ ◽  
Surface Roughening ◽  
Mechanistic Approach ◽  
Afm Imaging ◽  
Indentation Analysis ◽  
Single Crystal Sapphire

Contact which only involves a small volume of material is becoming increasingly important to many industries including micromachines, microelectronics, and magnetic recording. The ability to characterize surface roughening on the micro- and nanoscopic scale is invaluable in understanding microplasticity due to indentation, scratches, wear, fatigue and epitactic mismatch. It has been demonstrated that AFM studies are appropriate for developing a mechanistic approach to μN load indentation analysis since they allow deformation volumes and residual depths to be measured and characterized directly and unambiguously.In the present study, interfaces between silicate glass and single-crystal α-Al2O3 have been studied using AFM and nanoindentation. The interfaces between the glass and the crystalline grains were prepared by growing films of anorthite (CaAl2Si2O8) composition with thickness ranging 100-200 nm on single-crystal sapphire substrates of {1120} (A-plane) and {1102} (R-plane) crystallographic orientations by pulsed-laser deposition (PLD). Some specimens were subjected to heat treatments in a conventional box furnace causing films to dewet the substrates. Fig. 1 shows schematically the morphology of the dewetted film which has resulted in the formation of distinctive islands, 0.5-2 μm in size. Both types of specimens were tested with two different micro/nanomechanical testers.

Preparation of single-crystal diamond for Small Angle X-ray Scattering in situ loading test

2021 ◽  
pp. 108719
Author(s):  
X.C. Liu ◽  
X.G. Ge ◽  
Y.F. Li ◽  
X.M. An ◽  
L. Jiang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Small Angle ◽  
Loading Test ◽  
X Ray ◽  
X Ray Scattering ◽  
Single Crystal Diamond ◽  
Ray Scattering

Structural and Morphological Properties of Ultrathin HfO2 Dielectrics on 4H-SiC (0001)

2006 ◽  
Vol 527-529 ◽  
pp. 1075-1078 ◽  
Author(s):  
Carey M. Tanner ◽  
Jun Lu ◽  
Hans Olof Blom ◽  
Jane P. Chang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Field Effect Transistors ◽  
High Energy ◽  
Oxide Semiconductor ◽  
Ex Situ ◽  
Morphological Properties ◽  
Layer By Layer ◽  
Island Growth ◽  
X Ray

The material properties of HfO2 thin films were studied to evaluate their potential as a high-κ gate dielectric in 4H-SiC power metal-oxide-semiconductor field effect transistors. Stoichiometric HfO2 films were deposited on n-type 4H-SiC (0001) by atomic layer deposition (ALD) at substrate temperatures of 250-450°C. No significant interfacial layer formation was observed by in-situ X-ray photoelectron spectroscopy (XPS) and an abrupt interface was confirmed by high-resolution transmission electron microscopy (HRTEM). A temperature-dependent transition from amorphous layer-by-layer growth to crystalline three-dimensional island growth was identified by in-situ reflection high-energy electron diffraction (RHEED) and ex-situ atomic force microscopy (AFM). X-ray diffraction (XRD) confirmed the presence of monoclinic HfO2 domains in crystallized films.

scholarly journals Small AgNP in the Biopolymer Nanocomposite System

2020 ◽  
Vol 21 (24) ◽  
pp. 9388
Author(s):  
Małgorzata Zienkiewicz-Strzałka ◽  
Anna Deryło-Marczewska
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Metallic Nanoparticles ◽  
Silver Ions ◽  
Membrane System ◽  
Added Value ◽  
Ex Situ ◽  
Membrane Properties ◽  
Homogeneous Distribution

In this work, ultra-small and stable silver nanoparticles (AgNP) on chitosan biopolymer (BP/AgP) were prepared by in situ reduction of the diamminesilver(I) complex ([Ag(NH3)2]+) to create a biostatic membrane system. The small AgNP (3 nm) as a stable source of silver ions, their crystal form, and homogeneous distribution in the whole solid membrane were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The X-ray photoelectron spectroscopy (XPS) and Auger analysis were applied to investigate the elemental composition, concentration, and chemical state of surface atoms. It was found that ultra-small metallic nanoparticles might form a steady source of silver ions and enhance the biostatic properties of solid membranes. Ultra-small AgNP with disturbed electronic structure and plasmonic properties may generate interaction between amine groups of the biopolymer for improving the homogeneity of the nanometallic layer. In this work, the significant differences between the typical way (deposition of ex-situ-prepared AgNP) and the proposed in-situ synthesis approach were determined. The improved thermal stability (by thermogravimetry and differential scanning calorimetry (TG/DSC) analysis) for BP/AgP was observed and explained by the presence of the protective layer of a low-molecular silver phase. Finally, the antibacterial activity of the BP/AgP nanocomposite was tested using selected bacteria biofilms. The grafted membrane showed clear inhibition properties by destruction and multiple damages of bacteria cells. The possible mechanisms of biocidal activity were discussed, and the investigation of the AgNP influence on the bacteria body was illustrated by AFM measurements. The results obtained concluded that the biopolymer membrane properties were significantly improved by the integration with ultra-small Ag nanoparticles, which added value to its applications as a biostatic membrane system for filtration and separation issues.

scholarly journals Thermal Behavior of Single-Crystal Diamonds Catalyzed by Titanium Alloy at Elevated Temperature

2020 ◽  
Vol 10 (13) ◽  
pp. 4651
Author(s):  
Pengyu Hou ◽  
Ming Zhou ◽  
Haijun Zhang
Keyword(s):  
Titanium Alloy ◽  
Tool Wear ◽  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Elevated Temperatures ◽  
Tool Material ◽  
Alloy Sheet ◽  
Machine Material ◽  
X Ray ◽  
Single Crystal Diamond

Single-crystal diamonds are considered as the best tool material for ultra-precision machining. However, due to its low thermal conductivity, small elastic modulus and strong chemical activity, titanium alloy has poor machinability and is a typically difficult-to-machine material. Excessive tool wear prevents diamonds from cutting titanium alloy. This study conducts a series of thermal analytic experiments under conditions of different gas atmospheres in order to research the details of thermochemical wear of diamonds catalyzed by titanium alloy at elevated temperatures. Raman scattering analysis was performed to identify the transformation of the diamond crystal structure. The change in chemical composition of the work material was detected be means of energy dispersive X-ray analysis. X-ray photoelectron spectroscopy was used to confirm the resultant interfacial thermochemical reactions. The results of the study reveal the diffusion law of the single-crystal diamond under the action of titanium in the argon and air environment. From the experimental results, the product of the chemical reaction corresponding to the interface between the diamond and the titanium alloy sheet could be found. The research results provide a theoretical basis for elucidating the wear mechanism of diamond tools in the titanium alloy cutting process and for exploring the measures to suppress tool wear.

Sign in / Sign up

Export Citation Format

Share Document