Effect of SP3/(SP2+SP3) Carbon Fraction on the Photoelectric Threshold and Electron Affinity of Diamond Films

1998 ◽  
Vol 509 ◽  
Author(s):  
I.A. Akwani ◽  
E.D. Sosa ◽  
S.C. Lim ◽  
R.E. Stallcup ◽  
J.N. Castillega ◽  
...  
Keyword(s):  
Electron Affinity ◽  
Photoelectron Spectroscopy ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Negative Electron Affinity ◽  
Carbon Fraction ◽  
X Ray ◽  
Carbon Networks ◽  
Forms Of Carbon ◽  
Photoelectric Threshold

AbstractWe report a significant decrease in the photoelectric threshold of chemical vapor deposition grown diamond films as the fraction of sp3 carbon to sp2 plus sp3 carbon in the films decreases. Raman spectroscopy and x-ray photoelectron spectroscopy are used to characterize the different forms of carbon in the films and the sp3/(sp2 + sp3) carbon fraction at the surface. We observe a decrease in the photoelectric threshold from 4.5 eV to 3.9 eV as the sp3/(sp2 + sp3) carbon fraction at the surface decreases from 71% to 55%. Ultraviolet photoelectron spectroscopy of the films shows that they have a negative electron affinity surface. Therefore, the work function of the films decreases from 4.5 eV to 3.9 eV. We propose that the decrease in photoelectric threshold is due to a decrease in the band gap of sp2-sp3 carbon networks at the grain boundaries. The observed decrease in photoelectric threshold can be used to tailor the electronic properties of diamond films for specific applications.

X-ray Photoelectron Spectroscopy of the Interface Between Diamond Films and Tantalum Substrates

1993 ◽  
Vol 317 ◽  
Author(s):  
M.M. Waitew ◽  
S. Ismat Shah
Keyword(s):  
Photoelectron Spectroscopy ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Plasma Chemical ◽  
X Ray ◽  
Plasma Chemical Vapor Deposition ◽  
Stages Of Growth ◽  
Diamond Peak

ABSTRACTDiamond films were deposited in a microwave plasma chemical vapor deposition (MPCVD) system on Ta substrates using a mixture of hydrogen and methane gases. The films were grown for varying lengths of time to provide samples with no diamond growth to a continuous diamond film. These films were analyzed using X-ray photoelectron spectroscopy (XPS) in order to understand the time dependent interactions between the substrate and the incoming carbon flux. Photoelectron peaks in the Ta 4f, C Is and Ols regions have been analyzed. In the initial stages of growth, a layer of carbide forms on the substrate. As the substrate becomes supersaturated with carbon, graphite starts to form on the surface. A diamond peak begins to appear after about 30 Minutes of deposition.

Variation of the Photoelectric Threshold of Boron Doped Diamond Films

1998 ◽  
Vol 509 ◽  
Author(s):  
I.A. Akwani ◽  
E.D. Sosa ◽  
J. Bernhard ◽  
S.C. Lim ◽  
R.E. Stallcup ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Boron Doping ◽  
Boron Doped Diamond ◽  
Si Substrates ◽  
Band Emission ◽  
Boron Doped ◽  
Photoelectric Threshold

AbstractBoron doped polycrystalline diamond films grown on p-type single-crystal Si substrates using chemical vapor deposition with a gas mixture of hydrogen, methane and diborane were characterized with scanning electron microscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Raman spectroscopy and photoelectric current measurements. The energy distributions are not sensitive to boron doping for diborane concentrations from 0 to 4.75 ppm, although the boron doping modifies the surface morphology and the photoemission intensity. The photoemission intensity is high where the microcrystalline content is highest (at diborane concentrations of 2.91 and 4.75 ppm. The photoelectric threshold is found to be at 4.38 eV, in agreement with earlier measurements. The present results are characteristic of valence band emission at 4.38, 4.63, 4.92, 5.12 and 5.30 eV for incident photons between 4.87 and 5.63 eV.

Growth of diamond films and characterization by Raman, scanning electron microscopy, and x-ray photoelectron spectroscopy

1990 ◽  
Vol 5 (11) ◽  
pp. 2424-2432 ◽  
Author(s):  
S. C. Sharma ◽  
M. Green ◽  
R. C. Hyer ◽  
C. A. Dark ◽  
T. D. Black ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Methane Concentration ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Scanning Electron Micrographs ◽  
Xps Spectra ◽  
X Ray ◽  
Scanning Electron

We have deposited diamond films on Si〈111〉 using hot filament assisted chemical vapor deposition at low pressures ∼25 Torr. Diamond films deposited at different relative concentrations of methane (ranging from 0.25% to 2.0%) in methane-hydrogen mixtures have been characterized by Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. With varying methane concentration, Raman spectra show features characteristic of crystalline diamond, diamond-like carbon, and polycrystalline graphite. Scanning electron micrographs show densely packed diamond crystallites. SEM measurements made on diamond films grown as a function of time show that the median grain size of the diamond crystallites increases linearly with time during the initial phase of the growth. X-ray photoelectron spectroscopy reveals differences between the diamond sp3 covalent bonding and sp2 graphitic bonding as well as the extent of s-p hybridization as a function of methane concentration. The plasmon loss shoulder, characteristic of graphite, is absent from the spectrum of 0.25% methane concentration film. But it appears in the XPS spectra of films grown at higher concentrations.

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

Nitrogen (N2) Implantation to Suppress Growth of Interfacial Oxide in Mocvd Bst and Sputtered Bst Films

1999 ◽  
Vol 567 ◽  
Author(s):  
Renee Nieh ◽  
Wen-Jie Qi ◽  
Yongjoo Jeon ◽  
Byoung Hun Lee ◽  
Aaron Lucas ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Interfacial Layer ◽  
Gate Dielectric ◽  
Nitrogen Concentration ◽  
Chemical Vapor ◽  
Future Generation ◽  
Oxide Thickness ◽  
Layer Growth ◽  
X Ray ◽  
Bst Films

ABSTRACTBa0.5Sr0.5TiO3 (BST) is one of the high-k candidates for replacing SiO2 as the gate dielectric in future generation devices. The biggest obstacle to scaling the equivalent oxide thickness (EOT) of BST is an interfacial layer, SixOy, which forms between BST and Si. Nitrogen (N2) implantation into the Si substrate has been proposed to reduce the growth of this interfacial layer. In this study, capacitors (Pt/BST/Si) were fabricated by depositing thin BST films (50Å) onto N2 implanted Si in order to evaluate the effects of implant dose and annealing conditions on EOT. It was found that N2 implantation reduced the EOT of RF magnetron sputtered and Metal Oxide Chemical Vapor Deposition (MOCVD) BST films by ∼20% and ∼33%, respectively. For sputtered BST, an implant dose of 1×1014cm−;2 provided sufficient nitrogen concentration without residual implant damage after annealing. X-ray photoelectron spectroscopy data confirmed that the reduction in EOT is due to a reduction in the interfacial layer growth. X-ray diffraction spectra revealed typical polycrystalline structure with (111) and (200) preferential orientations for both films. Leakage for these 50Å BST films is on the order of 10−8 to 10−5 A/cm2—lower than oxynitrides with comparable EOTs.

scholarly journals Optical Constant and Conformality Analysis of SiO2 Thin Films Deposited on Linear Array Microstructure Substrate by PECVD

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 510
Author(s):  
Yongqiang Pan ◽  
Huan Liu ◽  
Zhuoman Wang ◽  
Jinmei Jia ◽  
Jijie Zhao
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Deposition Rate ◽  
Optical Constant ◽  
Photoelectron Spectroscopy ◽  
Linear Array ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
X Ray ◽  
Sio2 Thin Film

SiO2 thin films are deposited by radio frequency (RF) plasma-enhanced chemical vapor deposition (PECVD) technique using SiH4 and N2O as precursor gases. The stoichiometry of SiO2 thin films is determined by the X-ray photoelectron spectroscopy (XPS), and the optical constant n and k are obtained by using variable angle spectroscopic ellipsometer (VASE) in the spectral range 380–1600 nm. The refractive index and extinction coefficient of the deposited SiO2 thin films at 500 nm are 1.464 and 0.0069, respectively. The deposition rate of SiO2 thin films is controlled by changing the reaction pressure. The effects of deposition rate, film thickness, and microstructure size on the conformality of SiO2 thin films are studied. The conformality of SiO2 thin films increases from 0.68 to 0.91, with the increase of deposition rate of the SiO2 thin film from 20.84 to 41.92 nm/min. The conformality of SiO2 thin films decreases with the increase of film thickness, and the higher the step height, the smaller the conformality of SiO2 thin films.

High Quality GaAs Mis Diodes With Very Low Surface State Density

1990 ◽  
Vol 209 ◽  
Author(s):  
Yoshihisa Fujisaki ◽  
Sumiko Sakai ◽  
Saburo Ataka ◽  
Kenji Shibata
Keyword(s):  
Chemical Vapor Deposition ◽  
Density Of States ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
State Density ◽  
High Quality ◽  
Metal Insulator ◽  
X Ray ◽  
Mis Devices

ABSTRACTHigh quality GaAs/SiO2 MIS( Metal Insulator Semiconductor ) diodes were fabricated using (NH4)2S treatment and photo-assisted CVD( Chemical Vapor Deposition ). The density of states at the GaAs and SiO2 interface is the order of 1011 cm-2eV-1 throughout the forbidden energy range, which is smaller by the order of two than that of the MIS devices made by the conventional CVD process. The mechanism attributable to the interface improvement was investigated through XPS( X-ray Photoelectron Spectroscopy ) analyses.

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