Deep UV detection using a single crystal diamond (SCD) substrate without a homoepitaxial layer has been demonstrated using a defect passivation treatment. Despite evidence of surface damage on the SCD, the treatments lead to highly effective photoconductive devices, displaying six-orders of discrimination between deep UV and visible light and a responsivity as high as 100A/W, equivalent to an external quantum efficiency of 700, similar to the best values for devices based on high quality homoepitaxial layers. Impedance spectroscopic investigations suggest that the treatment used reduces the impact of less resistive surface material, most likely defects left from substrate polishing.

High quality single crystal and polycrystalline CVD diamond detectors with platinum contacts have been tested at the white beam X28C beamline at the National Synchrotron Light Source under high-flux conditions. The voltage dependence of these devices has been measured under DC and pulsed-bias conditions, establishing the presence or absence of photoconductive gain in each device. Linear response has been achieved over eleven orders of magnitude when combined with previous low flux studies. Temporal measurements with single crystal diamond detectors have resolved the ns scale pulse structure of the NSLS.

Block copolymers (BCPs) consist of two or more chemically distinct and incompatible polymer chains (or blocks) covalently bonded. Due to the incompatibility and connectivity constraints between the two blocks, diblock copolymers spontaneously self-assemble into microphase-separated nanoscale domains that exhibit ordered 0, 1, 2 or 3 dimensional morphologies at equilibrium. Commonly observed microdomain morphologies in bulk samples are periodic arrangements of lamellae, cylinders, or spheres. Block copolymer lithography refers to the use of these ordered structures in the form of thin films as templates for patterning through selective etching or deposition. The self-assembly and domain orientation of block copolymers on a given substrate is critical to realize block copolymer lithography as a tool for large throughput nanolithography applications. In this work, we survey the morphology of cylinder-forming block copolymers by atomic force microscopy (AFM). Three kind of block copolymers were studied: a) poly(styrene-block-ferrocenyldimethylsilane), PS-b-PFS b) poly(styrene-block-methylmethacrylate), PS-b-PMMA and c) poly(styrene-block-dimethylsiloxane) PS-b-PDMS. Block copolymers were dissolved in a neutral solvent for both blocks (toluene) in order to obtain solutions of various concentrations (1 and 1.5 wt %). From these solutions, films were prepared by spin casting on ultrananocrystalline diamond (UNCD) thin film substrates. Results indicate that PS-b-PFS exhibits chemical and morphological compatibility to the UNCD surface in terms of wetting and domain control. A systematic comparison of self-assembly of these polymers on silicon nitride substrates demonstrates that UNCD thin films would require pre-treatment to be considered as a substrate for BCP lithography.

Capacitive field-effect electrolyte-diamond-insulator-semiconductor (EDIS) structures with O-terminated nanocrystalline diamond (NCD) as sensitive gate material have been realized and investigated for the detection of pH, penicillin concentration, and layer-by-layer adsorption of polyelectrolytes. The surface oxidizing procedure of NCD thin films as well as the seeding and NCD growth process on a Si-SiO2 substrate have been improved to provide high pH-sensitive, non-porous thin films without damage of the underlying SiO2 layer and with a high coverage of O-terminated sites. The NCD surface topography, roughness, and coverage of the surface groups have been characterized by SEM, AFM and XPS methods. The EDIS sensors with O-terminated NCD film treated in oxidizing boiling mixture for 45 min show a pH sensitivity of about 50 mV/pH. The pH-sensitive properties of the NCD have been used to develop an EDIS-based penicillin biosensor with high sensitivity (65-70 mV/decade in the concentration range of 0.25-2.5 mM penicillin G) and low detection limit (5 μM). The results of label-free electrical detection of layer-by-layer adsorption of charged polyelectrolytes are presented, too.

Efficient and practical Raman lasers based on single crystal diamond are now realizable owing to the availability of optical quality crystals grown by chemical vapour deposition. In this paper, the performance characteristics of diamond Raman lasers is summarized and the results compared to other materials. The outlook for diamond Raman lasers is discussed and key challenges for material development highlighted.

Purification of diamond nanopowder (DNP) was conducted in a less-destructive mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5). The wide-angle X-ray diffraction (XRD) showed that the intensity of the characteristic diamond d-spacing (111) at 2.07 Å from purified DNP (PDNP) was fairly increased compared to pristine DNP, indicating that significant amount of carbonaceous impurities were removed. Chemical modification of pristine DNP and PDNP with 4-ethylbenzoic acid was carried out to afford 4-ethylbenzoyl-functionalized DNP (EBA-g-DNP) and PDNP (EBA-g-PDNP). The morphologies of EBA-g-DNP and EBA-g-PDNP from scanning electron microscopy (SEM) were further affirmed the feasibility of chemical modification. The results suggested that the reaction condition was indeed viable for the one-pot purification and functionalization of DNP. The resultant functionalized DNP could be useful for nanoscale additives. Hence, EBA-g-DNP and EBA-g-PDNP was brominated by using N-bromosuccinimide (NBS). The resultant N-brominated DNP and PDNP could be used as initiator for the atom transfer radical polymerization (ATRP) to introduce many polymers onto the surface of functionalized DNP and PDNP.

Conductive diamond films are essential for electronic applications of diamond but there is still a poor understanding of the effects that growth conditions, grain size and film thickness have on the ultimate conductivity of the film. One of the unique advantages of hot filament diamond is the ability to grow both MCD and NCD films to moderate thicknesses over large areas with little or no change in morphological characteristics such as grain size. In addition the grain size of the film can be altered without the necessity of adding additional gases to the process or unduly increasing the carbon to hydrogen ratio. This gives us an opportunity to investigate electrical conductivity as a function of grain size and thickness within a simple methane, hydrogen, and boron chemical environment over areas which are large enough to support significant production levels of MEMS and other diamond based electronics. In this study the boron source was selected to be trimethyl boron gas to avoid any source of oxygen which could alter the growth conditions and to guarantee that any byproducts of the dopant would be primarily methyl based. The films were grown to various thicknesses up to 5 micrometers and grain sizes from NCD to full MCD at all thicknesses. This paper explores the effects of both grain size and film thickness on the electrical conductivity of the film as well as the absolute doping levels within the film.

In the current work we report results of tribological testing of stable colloidal dispersions of detonation nanodiamond (DND) and polytetrafluoroethylene (PTFE) in mineral oil based greases as well as in polyalphaolefin (PAO) oil. Testing has been performed on these formula-tions using ring-on-ring, shaft/bushing and four ball test techniques. The test results demon-strated significant improvements for tribological characteristics (friction coefficient, extreme pressure failure load and diameter of wear spot) for certain formulations. A strong synergistic effect when using a combination of DND/PTFE additives was observed by a sharp decrease of friction coefficient. It was also demonstrated that using DND with smaller aggregate size (10nm versus 150nm) resulted in better lubricating performance of PAO-based composition.

A simple 1-dimensional Monte Carlo (KMC) model has been developed to simulate the chemical vapour deposition (CVD) of a diamond (100) surface. The model considers adsorption, etching/desorption, lattice incorporation, and surface migration along and across the dimer rows. The reaction probabilities for these processes are re-evaluated in detail and their effects upon the predicted growth rates and morphology are described. We find that for standard CVD diamond conditions, etching of carbon species from the growing surface is negligible. Surface migration occurs rapidly, but is mostly limited to CH2 species oscillating rapidly back and forth between two adjacent radical sites. Despite the average number of migration hops being in the thousands, the average diffusion length for a surface species is <2 sites.

The present paper outlines the energetic and kinetic effect by substitutional N, or by coadsorbed NHx (x =1, 2), on one of the key growth steps in the CVD growth mechanism of diamond (100); H abstraction by gaseous H radical species from the (100) surface plane. Theoretical calculations were performed based on Density Functional Theory under periodic boundary conditions. Substitutionally positioned N was shown to have a large effect on the H abstraction process. The H abstraction energy from the diamond surface was greatly improved with N positioned in C layer 2. In order to outline the effect by N on the growth rate, the barriers of energies were calculated. The barrier of abstraction was shown to substantially decrease with N substitutionally positioned in the second C layer, leading to an improvement of the abstraction reaction rate by approximately a factor of 3.

Single crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3±0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.

Industrial applications of PE MWCVD diamond grown on large area substrates, 3D shapes, at low substrate temperatures and on standard engineering substrate materials require novel plasma concepts. Based on the pioneering work of the group at AIST in Japan, high-density coaxial delivery type of plasmas have been explored [1]. However, an important challenge is to obtain commercially interesting growth rates at very low substrate temperatures. In the presented work we introduce the concept of novel linear antenna sources, designed at Leybold Optics Dresden, using high-frequency pulsed MW discharge. We present data on high plasma densities in this type of discharge (> 10 E11 cm-3), accompanied by data from OES for CH4 – CO2 - H2 gas chemistry and the basic properties of the nano-crystalline diamond (NCD) films grown.

Nanocrystalline diamond films (NCD) are strong candidates for applications in a wide variety of fields. An important concern in all these applications is to understand the properties of variously prepared NCD surfaces. This contribution is focussed on the surface science study of hydrogen and oxygen containing NCD films using X-ray photoelectron spectroscopy (XPS) as well as high resolution electron energy loss spectroscopy (HREELS). Previous studies have demonstrated that hydrogen, oxygen, and gases from the ambient environment as well as water can result in drastic surface changes affecting conductivity, wettability, tribological properties, etc. In this contribution we analyzed differently prepared NCD surfaces as a function of parameters such as the annealing temperature under ultrahigh vacuum conditions (UHV). We are able to identify the thermal stability of a number of species at the interface, which are related to different characteristics of C-H, C-OH, C=O, and C=C bonds. Furthermore, a formation of graphitic-like species appears at higher annealing temperatures. An atomic hydrogen treatment was also applied to the NCD surface to obtain further information about the surface composition.

Single layers of graphene (SLG) mechanically exfoliated from highly oriented pyrolytic graphite and deposited on SiO2/Si were irradiated with C+ ions at different fluences (from 1013 to 1014 cm-2), in order to modify the transport properties in controlled way. Using a method based on scanning probe microscopy, local measurements of the electron mean free path (l) have been carried out both on pristine and ion irradiated SLG. A lateral inhomogeneity of l was found in both cases, with an increasing spread in the distribution of l for larger fluences. Before irradiation, the spread was explained by the inhomogeneous distribution of charged impurities on SLG surface and/or at the interface with SiO2. After irradiation, lattice vacancies cause a local reduction of l in the damaged regions.

Various possible routes for the migration of a CH2 group between the H-terminated 2×1 reconstructed {100} surface and the H-terminated {111} surface of diamond have been explored using a hybrid quantum mechanical/molecular mechanical method. The calculated energies suggest that movement of such surface bound species across step edges should be a facile process under typical diamond growth conditions, and that such migrations are significant contributors to the observed morphologies of diamond grown by chemical vapor deposition methods.

A compact and efficient hot filament chemical vapor deposition system has been designed for growing electronic-grade diamond and related materials. We report here the effect of substrate rotation on quality and uniformity of HFCVD diamond films on 2” wafers, using two to three filaments with power ranging from 500 to 600 Watt. Diamond films have been characterized using x-ray diffraction, Raman Spectroscopy, scanning electron microscopy and atomic force microscopy. Our results indicate that substrate rotation not only yields uniform films across the wafer, but crystallites grow larger than without sample rotation. Well-faceted microcrystals are observed for wafers rotated at 10 rpm. We also find that the Raman spectrum taken from various locations indicate no compositional variation in the diamond film and no significant Raman shift associated with intrinsic stresses. Results are discussed in the context of growth uniformity of diamond film to improve deposition efficiency for wafer-based electronic applications.

Hydrogen incorporation is studied in two Microwave Plasma CVD nanocrystalline diamond films deposited with prolongated BIAS or not during the growth step. The hydrogen content and bonding forms are analysed by Secondary Ion Mass Spectrometry, Raman and Fourier Transformer Infrared Spectroscopy. Our results show a high hydrogen concentration up to 3.1021 cm-1, as expected in nanocrystalline diamond, and in good agreement with the sp2 phase rate measured by Raman spectroscopy . The FTIR spectra exhibit two sharp peaks at 2850 and 2920 cm-1 and show that a fraction of hydrogen is bonded to sp3 CH2 groups. Hydrogen desorption experiments are performed to analyse the local structure modification of the diamond films.

X-ray topography data are compared with photodiode responsivity maps to identify potential candidates for electron trapping in high purity, single crystal diamond. X-ray topography data reveal the defects that exist in the diamond material, which are dominated by non-electrically active linear dislocations. However, many diamonds also contain defects configurations (groups of threading dislocations originating from a secondary phase region or inclusion) in the bulk of the wafer which map well to regions of photoconductive gain, indicating that these inclusions are a source of electron trapping which affect the performance of diamond X-ray detectors. It was determined that photoconductive gain is only possible with the combination of an injecting contact and charge trapping in the near surface region. Typical photoconductive gain regions are 0.2 mm across; away from these near-surface inclusions the device yields the expected diode responsivity.

Current use of nanodiamond (ND) particles in electronic-related applications is mostly restricted to their role in seeding of substrates for growth of diamond films by chemical vapor deposition (CVD). While it is a niche application, nanometer-sized diamond particles are indispensable in this role. Seeding of substrates using a novel slurry of detonation nanodiamond particles in dimethylsulfoxide (DMSO) and methanol is one of the topics of this article. At the same time, optical applications of NDs, particularly development of photoluminescent NDs for biomedical applications is one of the most popular current research topics. In this paper perspectives for the use of detonation NDs and specifically the role of surface functionalization in imparting photoluminescent properties to detonation NDs as well as enhanced photoluminescence of proton irradiated ND-polydimethylsiloxane composites are discussed.

A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved, we have been developing models, within the VORPAL computational framework, to simulate secondary electron generation and charge transport in diamond. The implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will discuss these models and present results from 3D VORPAL simulations on charge gain and collection efficiency as a function of primary electron energy and applied electric field. The implemented modeling capabilities already allow us to investigate specific effects and compare simulation results with experimental data.