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"Properties Band Structure, Alan T. Collins Diamond Morphology, Robert E. Clausing Mechanical Properties of Diamond, Diamond Films, Diamond-Like Carbon, and Like-Diamond Materials, Peter J. Gielisse Surface Properties of Diamond, Mark P. D'Evelyn Thermal Properties Heat Capacity, Conductivity, and the Thermal Coefficient of Expansion, V. I. Nepsha Thermal Measurement Techniques, John E. Graebner Optical Properties, Alexander M. Zaitsev Electrical and Electronic Properties, Alexander G. Gontar Characterization Characterization Methods, Karen McNamara Rutledge and Karen K. Gleason Mined Diamond Natural Diamond, Henry O. A. Meyer and Michael Seal Theory Theory of Diamond Chemical Vapor Deposition, David G. Goodwin and James E. Butler Modeling and Diagnostics of Plasma Reactors Introduction, A. Gicquel Basic Processes in Plasmas Under Conditions Typical for Diamond Deposition, A. Gicquel Basic Processes: Plasma/Surface Interactions, A. Gicquel The Boltzmann Equation, Matt Gordon Flow Modeling for a Plasma Assisted Diamond Deposition Reactor, K. Hassouni, C. D. Scott, and S. Farhat Electromagnetic Field Modeling of Diamond CVD Reactors, Timothy A. Grotjohn Modeling of the Diffusional Transport of an H2 Plasma Obtained Under Diamond Deposition Discharge Conditions, K. Hassouni, C. D. Scott, and S. Farhat Spatially Resolved Spectroscopic Analysis of the Plasma, A. Gicquel, M. Chenevier, and M. Lefebvre Methods of Chemical Vapor Deposition Growth Hot-Filament CVD Methods, Alberto Argoitia, Christopher S. Kovach, and John C. Angus Microwave Plasma Chemical Vapor Deposition of Diamonds, Peter K. Bachmann Diamond CVD Using Radio-Frequency Plasmas, Steven L. Girshick Synthesis of Diamond, Mark A. Cappelli Low Temperature CVD, Akimitsu Hatta and Akio Hiraki Structural Modification of Diamond Nucleation and Epitaxy, S. P. Bozeman, B. R. Stoner, and J. T. Glass Ion Implantation of Diamond and Diamond Films, R. Kalish and S. Prawer Processing, Victor G. Ralchenko and Sergei M. Pimenov Applications of Industrial Diamond Abrasive Applications of Diamond, K. Subramanian and V. R. Shanbhag Active Devices, David L. Dreifus and Bradley A. Fox Applications of Diamond in Computers, Richard C. Eden Diamond Vacuum Electronics, George R. Brandes Special Applications, Naoji Fujimori Cutting and Wear Applications, R. A. Hay and J. M. Galimberti Economics Economics and Commercialization, Adam T. Singer and John V. Busch "

The color centers on the front and back of five free-standing diamond films grown by hot-filament CVD were characterized by cathodoluminescence and photoluminescence. The film quality was assessed by measuring the full width at half-maximum (FWHM) of the characteristic Raman diamond peak at 1332 cm−1. A correlation between the color center luminescence and the film quality was derived. The cathodoluminescence study clearly showed that the intensities of band A and the 600 nm emission band increased with increasing quality. Conversely, the intensity of the 1.68 eV photoluminescence decreased as the film quality improved. The lower intensity of the 1.68 eV luminescence in higher quality films, observed in the samples grown in a silicon-free reactor, is different from the usual 1.681 eV luminescence from silicon-related centers, which shows a greater intensity in higher quality films.

10 B doped diamond films grown by hot filament chemical vapor deposition were neutron irradiated for 4 weeks. The as-irradiated, and annealed samples, along with unirradiated samples, were analyzed using Raman, cathodoluminescence, and electrical conductivity measurements. The feasibility of the restoration of the quality of the irradiated films upon annealing was shown. The cathodoluminescence and electrical resistivity measurements showed that donor centers are formed during annealing in the irradiated samples. These donor levels may be Li atoms that move into interstitial sites of the lattice and become donors. The other possibility is the formation of donor levels owing to the interaction of Li atoms with some lattice defects induced by neuron irradiation. Prime novelty: transmutation doping of diamond using reaction 10 B (n, α) 7 Li.

10B doped diamond films grown by hot filament chemical vapor deposition were neutron irradiated at moderately high fluence levels. The as-irradiated and annealed samples, along with an unirradiated sample, were analyzed using Raman spectroscopy and x-ray diffraction. It was found that a non-diamond amorphous phase was formed on irradiation. This phase transformed back to diamond on annealing. No graphite formation was observed. A comparison with nanodiamond powder was made. A similarity between irradiated diamond films and nanocrystalline diamond powder is discussed.

Diamond films have been grown by hot filament chemical vapor deposition (CVD) on mirror-polished positively biased Si substrates. Very smooth films a few micrometers thick were obtained in only 30 min. SEM, x-ray diffraction patterns, and Raman were used to characterize the films. Not only diamond but other carbon phases, were also detected. The initial structure showed a high density of defects and large stresses. Structural changes in time were found to occur with films apparently undergoing a phase transformation.

Diffusion of boron, lithium, nitrogen, oxygen, and hydrogen into type IIa natural diamond was studied. The diffusion was performed in two steps. First, diffusion of Li and oxygen was performed in nitrogen atmosphere at 860 °C for one hour. The sample was then placed in a hot filament chemical vapor deposition (CVD) growth reactor and diffusion was performed for two hours in hydrogen atmosphere from a boron solid source placed on the surface of the sample. The condition of diffusion were those used routinely during CVD growth. After diffusion, the concentration of Li was of the order of 2×1016 cm−3 at the depth of 0.5 micrometer, and oxygen, nitrogen, and boron were found to be in the range (1–4)×1020 cm−3 at the same depth. The diffusion of hydrogen under conditions specific to CVD growth has also been studied for the first time and was found to be quite strong.

Diamond technology is a major area of worldwide semiconductor research. It has been said that the current status of diamond semiconductor technology is similar to that of silicon technology in 1960. Most of the research on diamond is in high quality film production (e.g., purity, and single crystalline versus polycrystalline). A few groups are concentrating on the development of diamond electronic devices. In this endeavor, both p-type and n-type diamond films have been produced. The p-type diamond has excellent properties while the ntype diamond is very high resistance. A primitive p-n junction has been demonstrated. Several groups have demonstrated Schottky diodes including the high bandgap semiconductor group at the University of Missouri-Columbia.

Summary and conclusions 1. lntroduction Diamond has great potential for electronic, optical. mechanical, chemical, and nuclear applications due to its superior properties. However. natural diamond is rare and expensive. being a metastable phase at normal pressure and temperature. The diamond synthesis at high temperatures and high pressures (HTHP), u her-e diamond is a stilble phase [I], was a breakthrough for large scale industrial applications. However, synthetic diamond is used mainly in abrasive and cutting tools industries [I], the crystals obtained by the HTHP method being too small and expensive for many applications in optics, electronics, or other industries [3]. Polycrystalline as well as single-crystal films of diamond on single-crystal diamond substrates were first obtained in the seventies by the Russian team of Spitsyn, Bouilov. Derjaguin, and coworkers [4 to 101 by the gas chemical transport reaction (CTR) method. Crystals of several micrometers in size and polycrystalline films, grown on various foreign substrates (Cu, Au, Si, W, Mo), were reported by the same team [8]. The discovery of the metastable growth of diamond films using atomic hydrogen and carbon containing gases or vapors at pressures belo~v atmospheric and not too high temperatures (600 to 1000 "C), has permitted diamond growth on non-diamond substrates.

Three natural type IIa diamond crystals were used for forced diffusion of boron. The diffusion was performed under bias otherwise with the same conditions. The boron diffusion coefficient in diamond was found to be 8.4 × 10−15 and 4 × 10−14 cm2/s at 1000 °C, depending on the direction of the electric field. The drift velocity of boron in diamond under 850 V at 1000 °C was found to be about 1.2 × 10−8 cm/s.

Polycrystalline high quality freestanding 300-μm-thick diamond films were doped by diffusion of B and Li under electric bias in order to fabricate vertical p-n junctions. Circular contacts were obtained by high dose ion implantation of B and Li. The I–V characteristics were rectifying. When illuminated by deuterium lamp, an open circuit voltage was 2.6 eV. The shape of the I–V characteristic under illumination points to the existence of shunt and series resistances. The obtained structure is most probably a p-n junction with bad contacts.

The amount of bonded hydrogen in polycrystalline diamond films grown by hot filament CVD at various deposition temperatures was measured by the thermal desorption method. The amount of hydrogen evolved from as-grown diamond films had the tendency to increase with deposition temperature. After vacuum annealing at 1470 K the samples were exposed to air at room temperature. It was shown that the presence of bonded hydrogen in these films was related to water adsorption on the diamond surface. The surface morphology of the films was studied by scanning electron microscopy. It was found that the higher the deposition temperature and the greater the sample thickness, the larger are the crystals with {111} faces.

Novel low energy molecular implantation of trimethyl phosphite was used to make rectifying junctions with indium contacts on boron doped diamond grown on silicon substrates. Diamond growth utilized hot‐filament enhanced chemical vapor deposition (HFCVD). To our knowledge, this is the first report of molecular implantation on diamond and the only implanted junction with HFCVD polycrystalline diamond on silicon as the starting material. The rectifying contacts have high current density in forward bias and exhibit linear inverse squared capacitance‐voltage characteristics at high frequencies, unlike other rectifying diamond junctions.

Schottky diodes were fabricated using sputter deposited silver contacts to boron doped polycrystalline diamond thin films grown by a hot‐filament chemical vapor deposition process with trimethyl borate as an in situ dopant source. High forward current density and a high forward‐to‐reverse current ratio were exhibited by these diodes. Current density‐voltage and capacitance‐voltage‐frequency characteristics of these diodes are very similar to those of Schottky diodes fabricated using a single‐crystal diamond substrate.

The doping of diamond and diamond films with electrically active impurities can be accomplish during synthesis [1], or by ion implantation [2]. An alternate method of doping with impurities in diamond is transmutation doping. It is especially important for realization of a n-type in diamond, the creation of which is complicated. Recently an opportunity for Li doping of diamond films by means of the reaction 10B (n,α)7Li [3,4] was shown. Transmutational doping is connected to formation of defects, rendering significant influence to the electrical and optical characteristics of the diamond films. In this work paramagnetic defects in the doped 10B initial diamond films, irradiated by neutrons and subjected to subsequent thermal annealing have been studied.

Nanophase diamond is a material obtained in an explosion of carbon containing charge in a closed vessel. It consist of two phases: diamond and metastable carbon phase which can be transformed into diamond upon annealing. Nanodiamond powder was hot pressed at 7.7 GPa in the temperature range 750–1400 °C. The metastable carbon phase was transformed into diamond by this method. Hot pressing binds the nanocrystals and transforms the powder into a bulk material approaching diamond quality. There will be a variety of applications for such a diamond material in various industries from aerospace to manufacturing.

A technique for radiation induced modifications is introduced. The process can be thought of as internal and uniform ion implantation. It has been shown that ion implantation can modify the surface properties of a material. However, its disadvantages are small and nonuniform interaction volumes. The proposed technique bypasses these limitations and could be suitable for large area modifications. This process could be used to form new composites and compounds. Additionally, the electronic and optical properties of materials could be specifically tailored. Promising experimental data using CVD diamond is presented.

Four CVD diamond films grown on tungsten carbide were used for diffusion. Diffusion was performed in a hydrogen atmosphere. Three methods of diffusion were used: conventional diffusion due to concentration gradient, forced diffusion under a dc electric bias with thermal ionization and forced diffusion with optical and thermal ionization of boron acceptor level in diamond. The temperature dependence of the electrical conductivity of the diffused samples was measured in the temperature range 300–600 K. The increase of approximately six order of magnitude in conductivity of the films doped by forced diffusion was obtained. The samples diffused with boron by conventional diffusion due to concentration gradient showed only one order of magnitude increase in electrical conductivity.

The experimental and theoretical results on would-be donor impurities in diamond lattice: N, P, Li, and Na, are reviewed. New methods of forced diffusion and ion assisted doping during growth are discussed. Experimental data on n-type conductivity obtained by forced diffusion into the diamond CVD films are also presented.

Diffusion of boron, hydrogen, oxygen and lithium in single crystalline and polycrystalline diamond is reported. Diffusion under DC electric field was used to enhance the diffusion rate. SIMS analyses were used to determine the impurity concentration. A novel method is proposed for the determination of the state of an impurity (donor, acceptor or deep level) in a semiconductor lattice. To demonstrate the method boron was diffused into Ia type natural diamond under a DC electric field. The concentration and diffusion profiles of boron were affected by the applied field. Boron diffuses as a negative ion since it is an acceptor shallow enough to be partially ionized at the temperature of diffusion. The drift velocity of boron ions at the temperature of diffusion was also estimated. Diffusion under DC electric field of lithium, oxygen and fluorine in high quality diamond films was also studied.

A study of boron diffusion into diamond lattice was performed. Diffusion was made in hydrogen atmosphere at 30 torr. Two type IIa diamonds were heated at 1200 and 1400 °C for 20 hours and 5 minutes, respectively. Boron powder was used as a dopant source. The boron concentration profiles of both samples were measured by secondary ion mass spectrometry. Based on Fick's law, the diffusion coefficients were computed.

The hydrogen content of free-standing polycrystalline CVD diamond samples was determined by Fourier Transform Infrared (FTIR) measurements and was quantified by a notched neutron spectrum technique. The latter measures the total bonded and unbonded hydrogen. The concentration of total hydrogen in these samples was of the same order of magnitude. The FTIR measurements, which are sensitive to the bonded hydrogen, indicated different hydrogen to diamond peak ratios.

Chemical vapor deposition (CVD) is widely used to grow diamond polycrystalline thin films. However at present the films synthesized by CVD contain a fairly large amount of defects. Electron Spin Resonance (ESR) has been used for the study paramagnetic impurities and defects, predetermine the physicochemical properties of synthetic diamond. The defects may present an important obstacle if the films are used as semiconducting materials. Correlations between the number of broken carbon bonds and conductivity in diamond [1], and diamond-like films [2] are being found. Over recent years the ESR study of diamond layers, grown by microwave plasma CVD [3,4] has been reported.

Undoped and 10B doped diamond films were neutron irradiated at a moderately high fluence level (thermal neutron fluence of 1.3 × 1020 n/cm2 and a fast neutron (E> 0.1 MeV) fluence of 1.6 × 1020 n/cm2). The unirradiated, irradiated, irradiated and annealed samples were studied using Fourier Transform Infrared (FTIR) and Raman spectroscopies. A dependence of radiation induced stress on the initial boron concentration was observed. The radiation induced stress was lower for the undoped samples. Correlations between FTIR and Raman data were found. The radiation damage was removed after annealing, as measured by Raman and FTIR spectroscopy.

Aluminum nitride (AlN) films were grown by chemical vapor deposition (CVD) on boron-doped diamond films deposited by the hot-filament CVD (HFCVD) method. The films were characterized by scanning electron microscopy, x-ray diffraction, and Raman spectroscopy. The electrical characterization of the AlN/diamond interface was performed by current-voltage (I-V) and capacitance- voltage measurements. The resulting films showed one x-ray diffraction peak of (100) oriented AlN and three diamond diffraction peaks of (111), (220) and (331) orientation. The Raman spectra showed two peaks, one at 660 cm-1 due to scattering by the AlN lattice and the other at 1335 cm-1 by the diamond lattice. The I-V measurements on the metal(W)/diamond/Si/Al structure showed ohmic behavior from which the diamond film resistivity of 5 X 105 (Omega) -cm was estimated. The I-V measurements on the W/AlN/diamond/Si/Al structure showed rectifying behavior. The capacitance of the film was independent of the applied voltage and was dominated by the diamond bulk capacitance.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper is a review on would-be donor impurities in diamond lattice: N, P, Li, and Na. Other impurities like oxygen and sulfur are also discussed. As the solubility of donor impurities in the diamond lattice is predicted to be low, new methods of forcing the introduction of impurities into the diamond lattice are discussed. We propose a new method of electric-field-assisted diffusion and a method of increasing the sticking coefficient of the impurities by growth under electric bias. We also discuss the method of ion-assisted doping during growth proposed by a research group from SI Technologies.

The content of bonded hydrogen in hot filament grown diamond films was determined by Fourier transform Infrared (FTIR) measurements before and after annealing. The quantity of bonded hydrogen was found to remain unchanged on annealing in diamond films with high amounts of microcrystalline diamond and amorphous carbon. The hydrogen content was found to decrease on annealing ∼9 times in diamond film of good crystalline quality. The change of the bulk hydrogen content did not seem to be linked to changes in resistivity of the samples.

Li salts (LiCiO 4 and Li 2 CO 3 ) were used for diffusion under bias in polycrystalline diamond films. Hot-probe and conductance measurements were performed. A change in conductance of more than 10 orders of magnitude due to diffusion was observed. The p-type conductivity was obtained by conventional hot-probe measurements. The sign of the thermoelectric power was found to depend on the electric field normal to the surface. A hypothesis was advanced regarding the existence of a p-type inversion layer on the surface of the n-type bulk diffused layer.

Metal/semiconductor unipolar barrier structures with boron-doped polycrystalline diamond films were fabricated and their electrical and photoelectric properties investigated. The photovoltage of a photoconverter exceeded 0.7 V as measured in open circuit and could be controlled by the bias voltage. A memory effect was evidenced in metal/polycrystalline diamond structures which consists of an increasing photovoltage after a short time biasing.

The crystalline quality of a diamond film with two different preferential orientations (100) and (111), obtained in the same run by hot filament chemical deposition, has been studied. The quality of the film determined by Raman spectroscopy measurements was found to be nearly the same for both orientations. The second order Raman spectrum for diamond film was observed by using an infrared excitation.

The diffusion of oxygen, lithium, chlorine, and fluorine in CVD diamond films was performed under bias at 700 and 1000 °C. SIMS and Auger analyses were used to determine the impurity concentration. After diffusion, the concentrations of Li and O in the diamond films were found to be of the order of (3–4)×1019 cm-3. The fluorine concentration was of order of (l-2)×1017 cm-3. The conductivity was p-type. The change in the resistivity due to diffusion was nearly nine orders of magnitude for the sample diffused under electric field, and six orders of magnitude for the samples diffused without field. No dependence of the impurity concentration on the applied bias was observed except for fluorine. The fluorine concentration dependence on the electric field indicates that fluorine may have formed a shallow level in the diamond band gap. The fact that large concentrations of impurities can be diffused into diamond films at relatively low temperatures indicates the presence in the films of many lattice defects (including grain boundaries).

High quality, freestanding “white” CVD diamond films, 230 μm thick, polished on both sides and with resistivity 10 14 Ω cm were used for diffusion of impurities to obtain n-type conductivity. Diffusion of lithium, oxygen and chlorine was performed under a bias. Auger analysis was used to determine the impurity concentrations. After diffusion, the concentrations of Li, O and Cl in the diamond films were found to be about (3–4) × 10 19 cm −3 . Raman scattering, cathodoluminescence, microwave photoconductivity, electron spin resonance, optical absorption, Hall effect and electrical conductivity measurements were employed for the film characterization. The measurements showed that the initial high structural quality of the film was not deteriorated after diffusion. The hall effect measurements showed n-type conductivity. The sheet resistance of the diffused layer was 10 5 Ω/□. The carrier mobility was estimated to be about 50 cm 2 V −1 s −1 .

Smooth diamond films have been grown by hot filament chemical vapor deposition under d.c. bias on mirror-polished Si substrates. Films a few micrometers thick were obtained in 30 minutes. Raman spectra showed very broad diamond peaks. X-ray diffraction showed the presence of diamond and also other carbon phase with a line 2.11 Å. With time, the films apparently underwent a phase transformation.