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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 "

Quantitative information on acceptor concentration, donor concentration and donor activation energy has been obtained for Si-doped GaN epitaxial layers grown by reactive MBE through simultaneous fitting of the temperature dependent Hall mobility ( μ ) and carrier concentration ( n ) data. The analysis indicates that the electron mobility at high temperatures is significantly influenced by crystal defects. But the dominant scattering at low temperatures is by ionized impurities. Fitting the mobility data over a wide temperature range yields a good estimate of the acceptor concentration ( N A ) in the sample which is then used as a known parameter in the fit to the n vs T data in order to determine the other important parameters, namely the donor activation energy ( E D ) and donor concentration ( N D ). Correct estimation of N A is very important because the fitted value of E D is very sensitive to the value of N A . For a good fit, two donor levels had to be used in all the Si-doped GaN layers except in a sample grown at relatively lower temperature. The thermal activation energies of the shallower donor levels determined in different samples range from 4.5 to 8.9 meV, and are consistent with screened hydrogenic donors in GaN. The deeper levels are from 77 to 122 meV in different samples and not hydrogenic.

Mg-doped GaN samples prepared by reactive molecular beam epitaxy have been investigated in an attempt to gain insight into the impurity incorporation and the origin of auto doping in otherwise undoped GaN films. The Hall and secondary ion mass spectroscopy data were utilized for the analysis of possible background impurities such as Si, O, and H in an effort to ascertain whether the background electron concentration is of impurity origin or native defect origin. The data appear to support the N vacancy as a possible cause of auto-n-type doping seen in undoped GaN. The effect of the ammonia flow rate on the incorporation of Mg atoms in GaN films and on the behavior of H were studied for layers grown on c-plane sapphire as well as 6H–SiC. Increased incorporation of Mg with larger ammonia flow rates is attributed to Ga vacancies and accompanying site selection. Moreover, p-GaN films grown under high ammonia flux are reported with a hole concentration, mobility, and resistivity of about 8×1017 cm−3, 26 cm2/V ...

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.

Aluminium nitride films were grown on silicon substrates using the chemical vapour deposition (CVD) method. The properties of the films were studied by scanning electron microscopy (SEM), atomic force microscope (AFM) measurements, X-ray diffraction and Raman scattering. The resulting films were strongly textured and had a preferential orientation with the c-axis normal to the surface, the Raman spectra showed two peaks at 607 and 653 cm−1 and two large bands at 750 and 900 cm−1 of smaller intensity. Both the macro- and micro-Raman spectra showed the same peaks.

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.

Likely contamination of GaN films by impurities emanating from Al2O3, SiC and ZnO substrates during growth has been studied by secondary ion mass spectrometry analysis. The highly defective interfacial region allows impurities to incorporate more readily as comparedjo the equilibrium solubility in a perfect crystal at a given temperature as evidenced by increased impurity levels in that region as detected by SIMS. The SIMS measurements in GaN layers grown on SiC and sapphire showed large amounts of Si and O, respectively, within a region wider than the highly disordered interfacial region pointing to the possibility of impurity diffusion at growth temperatures. The qualitative trend observed is fairly clear and significant. These observations underscores the necessity for developing GaN and/or AlN substrates.

Effects of well thickness and Si doping on the optical properties of GaN/AlGaN (MQWs) have been investigated by picosecond time-resolved photoluminescence (PL) measurements. Our results have yielded that (i) the optical transitions in nominally undoped MQWs with narrow well thicknesses (Lw 40 A) at low temperatures, and (iii) Si doping improved significantly the crystalline quality of MQWs of large well thicknesses (Lw>40 A). The implications of these results on the device applications based on III-nitride MQWs have been discussed.

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.

Pt2Si Schottky‐barrier diodes were found to exhibit excellent photoresponse in the wavelength region of 116.4–221.4 nm when they were operated in the front illumination mode. Quantum efficiencies as high as 220% were achieved, depending on the substrate resistivity used and the Pt2Si film thickness.

Picosecond time-resolved photoluminescence (TRPL) has been employed to study the effects of well thickness on the light emission properties and recombination dynamics in In/sub x/Ga/sub 1-x/N/GaN and GaN/Al/sub x/Ga/sub 1-x/N multiple quantum wells (MQWs) grown both by metal-organic chemical vapor deposition (MOCVD) and reactive molecular beam epitaxy (MBE). In this work we present results from a set of MOCVD grown In/sub x/Ga/sub 1-x/N/GaN and a set of MBE grown GaN/Al/sub x/Ga/sub 1-x/N MQW samples with well thicknesses varying from 20 to 90 /spl Aring/. Results from these MQW samples are compared with each other and also to InGaN and GaN epilayers to extrapolate the mechanisms and quantum efficiency of the optical emission in these structures. The implications of these results on device applications, in particular for blue LEDs and laser diodes will be discussed.

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.

Transmutation doping of (In, Ga, Al)N compounds by neutron irradiation is a promising and totally unexplored field to date. It is much more effective than that of Si due to large neutron capture cross section and abundance of In, Al and Ga isotopes participating in reaction. This should make the irradiation possible in low-flux reactors and result in smaller radiation damage. Annealing of the radiation damage seems feasible.

Fundamental optical transitions in GaN and InGaN epilayers, InGaN/GaN and GaN/AlGaN multiple quantum wells (MQWs) grown both by metal-organic chemical vapor deposition and reactive molecular beam epitaxy have been studied by picosecond time-resolved photoluminescence spectroscopy. The exciton binding energies and radiative recombination lifetimes of the free excitons and bound excitons have been obtained. Effects of well thickness on the optical properties of In/sub x/Ga/sub 1-x/N/GaN and GaN/Al/sub x/Ga/sub 1-x/N MQWs have also been studied.

Raman, photoluminescence, and Hall measurements are reported for Mg doped GaN films grown by molecular beam epitaxy. The compressive and tensile stress determined by the Raman shift of the phonon lines is due to the growth conditions rather than the presence of Mg in the film. The photoluminescence peak of near band-to-band transitions is also shifted to larger (smaller) energies by the compressive (tensile) stress. The study of the longitudinal optical phonon of the Ai branch shows that its Raman line shape is affected not only by phonon-plasmon interactions but by the crystalline quality of the film, as well.

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.

Wide bandgap materials will have many applications as coatings and as electronic devices. This paper describes an electronic application for wide bandgap materials in energy production. A specific portable power technology which converts the energy emitted from nuclear reactions to electrical energy using wide bandgap photovoltaic cells without intermediate thermalization is described in this paper. The potential efficiency for the photovoltaic process is 35%, nuclear energy to electrical energy. And, if combined with high-temperature thermionic conversion the nuclear to electrical energy conversion efficiency is 41% while the overall size of the system remains small. The key to the process is to first convert the high-grade ion energy to photon energy, which can then be directly converted to electrical energy. This process is also usable as an advanced topping cycle for large scale energy production in conjunction with fusion power, as well as fission power. In addition to improved efficiency, the process also promises advantages in smaller volumes, smaller mass, and lower cost of the energy conversion hardware.

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.

Schottky diodes to be used for mechanical stress effect studies were fabricated using aluminum contacts to polycrystalline diamond thin films grown by a hot-filament assisted chemical vapor deposition process. Compressive stress was found to have a large effect on the forward biased current-voltage characteristics of the diode. At selected values of constant forward biased current, a linear relationship between voltage and stress, for stress less than 10 N was observed. The stress sensitivity of the diode was as high as 0.74 V/N at 1 mA forward bias. This study shows that polycrystalline diamond Schottky diodes are stress sensitive devices and have potential as mechanical sensors.

On etudie par diffraction RX la structure cristalline et la microstructure de la ceramique ferroelectrique correspondant a la composition Pb 0,98 Bi 0,02 Zr 0,5 Ti 0,31 Fe 0,1 Nb 0,08 U 0,01 O 3 . On examine l'influence d'un traitement thermique et d'une polarisation sur les parametres microstructuraux

On etudie par diffraction RX la microstructure de ceramiques ferroelectriques de titanate de plomb substituees par des lanthanides

Large-area Cu2S/CdS solar cells were fabricated by vacuum evaporation technology alone. The Cu2S layer was obtained by the dry method, i.e. by evaporation of a CuCl film followed by a reaction bake. A CdS layer only 12 μm thick was sufficient to prevent the shunting problem. The as-deposited roughness ensured a high absorbance in the Cu2S layer without any etching. Good reproducibility was obtained by exposing the surface to a glow discharge in hydrogen. The maximum efficiency was 6.4% at 100 mW cm-2 illumination for a cell area of 11 cm2. Modules with typical peak power values of 0.3 and 1 W were fabricated and successfully tested.

The light emission from the reverse-biased GaAs p-n- junctions with substrate concentrations of 1.5 × 1017, 5 × 1017, 2.2 × 1018and 4.4 × 1018 cm-3 has been investigated. The omission spectra similar to that obtained for GaAs forward-biased junctions and the temperature dependence of the light emission intensity show that emission is due to the recombination of free electrons with holes on the acceptor level and occurs in the p side of the junction, as was observed at forward-biased diodes. Excess electrons are thrown in the conduction band of the p side of the junction by avalanche breakdown. The superlinearity of light intensity versus current characteristics is explained by the presence of non-radiative tunnel currents.

The spectral and current dependences of the luminescence of Ge-doped GaAs diodes were studied. A relation between the luminescence intensity J and the current I was found: I ∞ J1/n , where n = 5–7 for small forward currents and n = 1 for large forward currents. The exact relationship between the luminescence and the current is discussed bearing in mind the competition between possible recombination processes.

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.