Electronic Structure of Polycrystalline PECVD Diamond Surfaces

1995 ◽  
Vol 416 ◽  
Author(s):  
T. P. Humphreys ◽  
D. P. Malta ◽  
R. E. Thomas ◽  
J. B. Posthill ◽  
M. J. Mantini ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electron Emission ◽  
Hydrogen Plasma ◽  
High Vacuum ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Low Energy ◽  
Diamond Surfaces ◽  
Single Crystal Diamond

ABSTRACTUltraviolet and X-ray photoelectron spectroscopy techniques have been employed in a preliminary study of the electronic structure of polycrystalline diamond films that have been grown on Si substrates by if-plasma enhanced chemical vapor deposition using water/ethanol growth chemistries. In particular, polycrystalline diamond films with distinctly different surface morphologies and Raman scattering characteristics have been investigated. Corresponding ultraviolet photoemission spectra from air-exposed samples have shown the presence of a prominent low-energy secondary electron emission peak indicative of a negative electron affinity (NEA) surface. Chemical stability of the polycrystalline diamond NEA surface has been demonstrated following conventional acid cleans and hydrogen plasma processing. In contrast, an oxygen (20%)/Ar plasma exposure has been shown to extinguish the photoemission of low-energy secondary electrons and remove the NEA. However, by employing a high-temperature anneal at 750 °C for 15 min in ultra-high vacuum the NEA surface can be restored. Compared to NEA single crystal diamond surfaces the photoexcited low-energy electron emission from chemical vapor deposited polycrystalline diamond films is more robust.

Effect of Annealing and Microwave Hydrogen Plasma Treatment on Structural, Chemical, and Electronic Properties of Ion Irradiated Diamond Films

2000 ◽  
Vol 650 ◽  
Author(s):  
Alexander Laikhtman ◽  
Alon Hoffman
Keyword(s):  
Plasma Treatment ◽  
Electron Affinity ◽  
Electron Emission ◽  
Hydrogen Plasma ◽  
Diamond Films ◽  
Ion Bombardment ◽  
Near Surface ◽  
Diamond Surfaces ◽  
X Ray ◽  
Emission Properties

ABSTRACTIn the present study we correlate between the secondary electron emission (SEE) of variously treated Xe+ ion-damaged diamond films and their bonding structure in the near-surface region as identified by near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy. The 50 keV Xe+ ion bombardment of hydrogenated polycrystalline diamond films to a dose of 2×1015 cm−2 results in the transformation of near-surface diamond to sp2-bonded amorphous carbon, increased oxygen adsorption, shift of the electron affinity from negative to positive, and strong degradation of its electron emission properties, although it does not induce a pronounced depletion of hydrogen. Exposure of the ion-bombarded films to microwave (MW) hydrogen plasma treatment for 30 min produces negative electron affinity diamond surfaces, but only partially regenerates SEE properties, retains some imperfection in the near-surface atomic layers, as determined by NEXAFS, and the concentration of oxygen remains relatively high. Subsequent annealing to 610 °C produces oxygen-free diamond films and somewhat increases their SEE. Annealing to 1000 °C results in desorption of the surface hydrogen, formation of a positive electron affinity surfaces and drastically degrades their electron emission properties. Prolonged, up to three hours MW hydrogen plasma treatment of as-implanted diamond films gradually improves the crystal quality and results in further increase of SEE intensity. This treatment does not, however, substantially reduce the concentration of oxygen in the previously damaged diamond, indicating its bulk diffusion during or after ion bombardment. To fully recover electron emission properties it is necessary to both remove the defects and hydrogenate the diamond surfaces.

Electrical Properties of Hydrogen Terminated P-Type Diamond Film

2010 ◽  
Vol 663-665 ◽  
pp. 625-628
Author(s):  
Fu Yuan Xia ◽  
Lin Jun Wang ◽  
Jian Huang ◽  
Ke Tang ◽  
Ji Jun Zhang ◽  
...  
Keyword(s):  
Carrier Concentration ◽  
Microwave Plasma ◽  
Hydrogen Plasma ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Plasma Chemical ◽  
Plasma Chemical Vapor Deposition ◽  
P Type ◽  
Effect Method

Undoped high quality polycrystalline diamond films were grown by the microwave plasma chemical vapor deposition (MPCVD) method. The effects of hydrogen plasma treatment and vacuum annealing process on the p-type behavior of diamond films were investigated by the Hall effect method. The sheet carrier concentration increased and the sheet resistivity decreased with the treating time of hydrogen plasma and a stable value was achieved finally. After annealing the samples in vacuum at temperature above 600 °C, the sheet carrier concentration dropped dramatically. The origin of this hydrogen terminated p-type conductive layers is also discussed.

Growth Technique For Large Area Mosaic Diamond Films†

1992 ◽  
Vol 242 ◽  
Author(s):  
R. W. Pryor ◽  
M. W. Geis ◽  
H. R. Clark
Keyword(s):  
Single Crystal ◽  
Electronic Properties ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Growth Conditions ◽  
Large Area ◽  
Si Substrates ◽  
Single Crystal Diamond ◽  
The Individual

ABSTRACTA new technique has been developed to grow semiconductor grade diamond substrates with dimensions comparable to those of currently available Si wafers. Previously, the synthetic single crystal diamond that could be grown measured only a few millimeters across, compared with single crystal Si substrates which typically are 10 to 15 cm in diameter. In the technique described, an array of features is first etched in a Si substrate. The shape of the features matches that of inexpensive, synthetic faceted diamond seeds. A diamond mosaic is then formed by allowing the diamond seeds to settle out of a slurry onto the substrate, where they become fixed and oriented in the etched features. For the experiments reported, the mosaic consists of seeds ∼ 100 μm across on 100 μm centers. A mosaic film is obtained by chemical vapor deposition of homoepitaxial diamond until the individual seeds grow together. Although these films contain low angle (<1°) grain boundaries, smooth, continuous diamond films have been obtained with electronic properties substantially better than those of polycrystalline diamond films and equivalent to those of homoepitaxial single crystal diamond films. The influence of growth conditions and seeding procedures on the crystallographic and electronic properties of these mosaic diamond films is discussed.

Seeding With a Diamond Suspension for Growth of Smooth Polycrystalline Diamond Surfaces

1996 ◽  
Vol 423 ◽  
Author(s):  
I. St. Omer ◽  
T. Stacy ◽  
E. M. Charlson ◽  
E. J. Charlson
Keyword(s):  
Surface Roughness ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Diamond Powder ◽  
Diamond Surface ◽  
Nucleation Density ◽  
Diamond Grit ◽  
Diamond Surfaces ◽  
Carrier Fluid

AbstractA number of techniques have been used to smooth polycrystalline diamond films. Recent work in substrate seeding with nanocrystalline diamond powder, alone or in a carrier fluid, has shown that diamond seeding improves nucleation density and reduces diamond surface roughness. In this work, silicon substrates were seeded using a commercially available waterbased 0.1 micrometer diamond polishing suspension. Growth was achieved using conventional hot-filament chemical vapor deposition (HFCVD). Films were characterized using optical microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD), and surface profilometry. The resulting diamond films exhibited well-faceted crystals, small grain size and minimal surface roughness. Additionally, the silicon substrate was chemically etched in order to permit examination of the backside of the diamond film. Results show that the diamond surface at the silicon-diamond interface is ultra-smooth. Comparison of the backside of these surfaces with those prepared using conventional diamond grit abrasion indicates that a significant improvement in surface quality is achieved using this diamond seeding technique.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

Low energy ion-induced damage of polycrystalline diamond films

1994 ◽  
Vol 3 (4-6) ◽  
pp. 663-671 ◽  
Author(s):  
J. Ullmann ◽  
A. Weber ◽  
B. Mainz ◽  
J. Stiegler ◽  
T. Schuhrke
Keyword(s):  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Low Energy

Fibrous structures on diamond and carbon surfaces formed by hydrogen plasma under direct-current bias and field electron-emission properties

2003 ◽  
Vol 18 (2) ◽  
pp. 305-326 ◽  
Author(s):  
Koji Kobashi ◽  
Takeshi Tachibana ◽  
Yoshihiro Yokota ◽  
Nobuyuki Kawakami ◽  
Kazushi Hayashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Direct Current ◽  
Electron Emission ◽  
Microwave Plasma ◽  
Hydrogen Plasma ◽  
Polycrystalline Diamond ◽  
Metal Catalyst ◽  
Direct Current Bias ◽  
Conical Structures

Polycrystalline diamond films, single crystal bulk diamonds, and diamond powder were treated in microwave plasma of hydrogen at 1.6 torr under a negative direct-current bias of −150 to −300 V without metal catalyst. It was found that fibrous structures, uniformly elongated along the direction normal to the specimen surface, were formed on the diamond surfaces. Similar experiments for glasslike carbon resulted in conical structures with frizzy fibers at the tops. Transmission electron microscopy measurements indicated that the fibers formed on diamond consisted of randomly oriented diamond nanocrystals with diameters of less than 10 nm, while the conical structures formed on glasslike carbon consisted of graphite nanocrystals. Field emission measurements of the fibrous specimens exhibited better emission efficiency than untreated ones. The field emission electron microscopy of the fibrous glasslike carbon showed a presence of discrete electron emission sites at a density of approximately 10,000 sites/cm2.

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