Clément Hébert (a), Davy Carole (c), Franck Omnes (a), Etienne Gheeraert (a)

International audienceNanopores in insulating solid state membranes have recently emerged as potential candidates for sorting, probing and manipulating biopolymers, such as DNA, RNA and proteins in their native environment. Here a simple, fast and cost-effective etching technique to create nanopores in diamond membrane by self-assembled Ni nanoparticles is proposed. In this process, a diamond film is annealed with thin Ni layers at 800-850 degrees C in hydrogen atmosphere. Carbon from the diamond-metal interface is removed as methane by the help of Ni nanoparticles as catalyst and consequently, the nanoparticles enter the crystal volume. In order to optimize the etching process and understand the mechanism the annealed polycrystalline and nanocrystalline diamond films were analyzed by X-ray photoelectron spectroscopy (XPS), and the gas composition during the process was investigated by quadrupole mass spectrometer. With this technique, nanopores with lateral size in the range of 15-225 nm and as deep as about 550 nm in diamond membrane were produced without any need for lithography process. A model for etching diamond with Ni explaining the mechanism is discussed

Recent progress of diamond device toward power application

International audienceThe state of the art of the Institut Néel research activity in the field of diamond power devices will be described and discussed. The active layers of the device are based on boron-doped monocristalline (100) diamond (with doping level varying between 1014 to 1021 cm-3) grown on Ib high temperature high pressure (HPHT) diamond substrate. The progresses done on diamond/metal interface, diamond/dielectric interface, or sharp gradient doping, permit recently the fabrication of original structures and devices, which will be detailed here (Schottky diode, boron doped δ-FET and MOS capacitance)

Electronic and physico-chemical properties of nanmetric boron delta-doped diamond structures

Heavily boron doped diamond epilayers with thicknesses ranging from 40 to less than 2 nm and buried between nominally undoped thicker layers have been grown in two different reactors. Two types of [100]-oriented single crystal diamond substrates were used after being characterized by X-ray white beam topography. The chemical composition and thickness of these so-called deltadoped structures have been studied by secondary ion mass spectrometry, transmission electron microscopy, and spectroscopic ellipsometry. Temperature-dependent Hall effect and four probe resistivity measurements have been performed on mesa-patterned Hall bars. The temperature dependence of the hole sheet carrier density and mobility has been investigated over a broad temperature range (6K<T<450 K). Depending on the sample, metallic or non-metallic behavior was observed. A hopping conduction mechanism with an anomalous hopping exponent was detected in the non-metallic samples. All metallic delta-doped layers exhibited the same mobility value, around 3.660.8 cm2/Vs, independently of the layer thickness and the substrate type. Comparison with previously published data and theoretical calculations showed that scattering by ionized impurities explained only partially this low common value. None of the delta-layers showed any sign of confinement-induced mobility enhancement, even for thicknesses lower than 2 nm.14 page

Wide-bandgap semiconductor ultraviolet detectors (Topical Review)

International audienc

Comparison of the XPS spectra from homoepitaxial {111}, {100} and polycrystalline boron-doped diamond films

International audienceIn this work, we have used X-ray photoelectron spectroscopy (XPS) to investigate the nature of surface adsorbed species and their sensitivity to the boron concentration [B] in two sets of as-grown diamond films: homoepitaxial {111} and polycrystalline. These sets cover each one at least three of the four doping ranges: low doping (5 x 10(16)2 x 10(21) cm(-3)). The results are compared to those we have previously obtained on (100) homoepitaxial films in the same doping ranges. A detailed description of both the nature and the relative concentrations of the main surface chemical species on every set of films is reported. Besides the usual CHx bonds on the diamond surface, the following oxygen-related groups: Ether (C-O-C), hydroxyl (C-OH, only on polycrystalline films), carbonyl (>C=O) and carboxyl (HO-C=O) have been found on the surface of grown diamond films, upon spontaneous oxidation under air (no oxidation treatment has been applied). The evolution of each surface chemical group according to the boron concentration in the films is

Raman characterization of boron-doped {111} homoepitaxial diamond layers

International audiencep-type {111} homoepitaxial diamond layers were grown by Microwave Plasma-Enhanced Chemical Vapor Deposition. The variation of the gas phase boron concentration led to solid-state incorporation of boron in the 6 · 10163 · 1021 cm 3 range. Confocal Raman spectroscopy and Raman imaging have been used to investigate this series of homoepitaxial films. As already observed for undoped or phosphorous-doped {111} epilayers, a first noticeable feature was the presence of many sharp and weak lines peaking at random in the 5002000 cm 1 range. These peaks were all the most observed that the doping level was low. A number of boron-related Raman lines centered at about 610, 925, 1045 cm 1 were observed for solid state boron concentrations in the 1.5 · 10189 · 1019 cm 3 range. Above a boron concentration of 3 · 1020 cm 3, the usual Raman signal of heavily boron-doped diamond was recorded. The thickness of the epitaxial layers, in the 0.22 μm range, was too low to allow a more detailed analysis of the zone-center diamond optical phonon

n-type phosphorus-doped polycrystalline diamond on silicon substrates

International audienceThe microwave plasma-assisted deposition of reproducible and homogeneously n-type phosphorus-doped polycrystalline (microcrystalline) diamond films on silicon substrates is described. The phosphorus incorporation is obtained by adding gaseous phosphine (PH3) to the gas mixture during growth. The low CH4/H2 ratio (0.15%) and the use of the same growth parameters as for homoepitaxial {111} films, led to a good crystalline quality of the continuous polycrystalline diamond layers, confirmed by SEM images and Raman spectroscopy measurements. Secondary-ion mass spectrometry (SIMS) analysis measured a phosphorus concentration [P] of at least 7×1017 cm−3. Cathodoluminescence spectroscopy in our P-doped polycrystalline films shows a phosphorus bound exciton (BETO P) peak between 5.142 and 5.181 eV. Cathodoluminescence and Raman-effect spectroscopy confirmed the improvement of the crystalline quality of our films as well as a decrease in the intensity of the internal strain when the grain size was decreased. Cathodoluminescence imaging and SIMS depth profile of phosphorus demonstrated a very good homogeneity of phosphorus incorporation in the films

Study of boron doping in MPCVD grown homoepitaxial diamond layers based on cathodoluminescence spectroscopy, secondary ion mass spectroscopy and capacitance-voltage measurements

International audienceBoron incorporation from the gas phase was achieved in MPCVD grown (100)-oriented homoepitaxial diamond layers, either with or without a small fraction of oxygen in the gas phase, in addition to hydrogen, methane and diborane. From secondary Ion Mass Spectroscopy (SIMS), it is shown that the 0.25% of oxygen decreases the Boron concentration [B] by two orders of magnitude. In this way, we demonstrate that it becomes possible to control [B] with low levels of compensation and passivation down to the 10(15) cm(-3) range. Cathodoluminescence spectroscopy is systematically performed in seventeen samples under a 10 kV acceleration voltage at 5 K and the exciton bound to boron (BE(TO)) intensity to the free exciton (FE(TO)) intensity ratio is evaluated (I(BETO)/I(FETO)). A linear relationship between I(BETO)/I(FETO) and FBI with a coefficient of 3.5 x 10(16) cm(-3) is demonstrated for [B]< 3 x 10(17) cm(-3) in single crystalline diamond, irrespective of the gas phase composition during growth