Diamond is a key material for quantum devices and sensors, microelectromechanical systems, and the next-generation electronic devices. Microfabrication technology of single-crystal diamond (SCD) for device fabrication and processing is required but hardly established. For example, photolithographic techniques using plasma induced etching for the microfabrication of the diamond devices induce damage to its diamond and deteriorate the device-performances. To overcome this problem, we proposed a plasma-free imprint lithographic technique of SCD using nickel (Ni) mold at high temperatures. Prior to contacting with SCD, the native surface oxide film of the Ni mold was reduced by a hydrogen annealing treatment. Then, the samples were contacted with Ni mold closely, and annealed at various temperatures from 800 to 1200 degrees C for 30 min, aiming at the formation of the microstructure on the SCD surface by imprinting the structure of Ni mold based on the carbon solid solution reaction into Ni. After removing the Ni and the formed graphite by acid treatment from the SCD surface annealed at 1000 degrees C, imprints with Ni shape structure are revealed on the SCD surface. This microstructure formation processes requires only short periods of time without any specific equipments. Therefore, this diamond imprint lithography is significant and practical for the development of diamond applications.

Hall experiments performed on intrinsic, phosphorus and boron doped a-Si:H and a-SiC:H in the temperature regime 200 K ≤ T ≤ 400 K are introduced and discussed. The data confirm the double sign anomaly meaning the Hall coefficient is p-type on intrinsic and phosphorus doped a-Si:H and a-SiC:H, and n-type on boron doped a-Si:H. The Hall mobilities, μΗ, are significantly smaller than the drift mobilities, decreasing with increasing doping and/or carbon content. μΗ of holes is about half that for electron which indicate that μΗ scales approximately with 1/Es, where E, is the tail slope. The presented interpretation of the Hall coefficient, that is introduced to be a function of Hall- and drift-mobility, enables the accurate determination of the carrier density in intrinsic and doped amorphous silicon and alloys from Hall data.

U-shaped diamond trenches with vertical {111} sidewalls for power devices were successfully obtained by anisotropic etching of diamond (110) surfaces using Ni films in high-temperature (1000 degrees C) water vapor. The etching rate for the diamond (110) surfaces was estimated to be 3.8 mu m/min on the basis of the relationship between etching time and etching depth of diamond trenches with (110) bottoms. These (110) bottoms gradually disappeared as the etching progressed. Finally, they completely vanished and each diamond trench was surrounded by four vertical {111} sidewalls and two slanted {111} sidewalls. The formation mechanisms of the U-shaped diamond trenches are also discussed on the basis of the experimental results.

The influence of temperature, pressure and holder geometry on the homoepitaxial single crystalline diamond growth in a microwave-assisted chemical vapor deposition reactor will be introduced and discussed in detail. Optimized diamond growth conditions were determined for homoepitaxy on (100)-oriented high-temperature high-pressure (HPHT) seed crystals using Raman scattering and confocal-micro-photoluminescence spectroscopy measurements.

For a long time sp2 carbon has been the dominating material for supercapacitor applications. In this paper a new concept of using boron-doped diamond for supercapacitors is proposed. Diamond surface enlargement is realized via bottom-up template-growth. In this method, silicon nanowire electrodes are coated with a thin (~100nm) layer of nanocrystalline diamond (NCD) by microwave enhanced chemical vapor deposition (MWCVD). The quality of overgrowth is characterized by high resolution scanning electron microscopy which reveals a homogeneous coverage of diamond on Si nanowire surface. To enhance the potential window to 4V, a room temperature ionic liquid is used as electrolyte. The dilution of the ionic liquid is investigated in terms of conductivity and specific capacitance. The capacitance as measured via cyclic voltammetry reaches 105μF/cm2. An energy density of 84μJ/cm2 and a high power density of 0.94mW/cm2 are obtained in combination with good stability of over 10,000charging/dischargingcycles.

A combined layer structure of aluminum nitride (AlN) and silicon nitride (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> ) enables the fabrication of multisegment piezo-actuated micro lenses with a precise control of the lens surface. It is demonstrated that these micro lenses offer free aspheric deformation of the lens surface and can operate at high repetition rates along with reproducible and precise tunability. The AlN/Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> micro lenses are highly advantageous to be used as wave front filter or for fast focus correction.

Single crystalline diamond nanowires of different sizes and shapes were fabricated with electron beam lithography and inductively coupled plasma etching using oxygen. Titanium and chromium have been used as etching mask, where titanium appeared to be more chemically resistant. We were able to fabricate nanowires from 60nm diameter to 200nm with a length of approximately 1μm. As the nanowire should be used in the future as a waveguide for the NV fluorescence originating from the apex of the structure, simulations were done with Comsol Multiphysics in order to determine the dependency between shape and guidance properties.

Pseudocapacitive materials exhibit high energy storage, but their energy release is slow. In this paper we aim at solving this problem by using diamond‐nickel hydroxide composite wires as a high power supercapacitor material. Diamond nanowires serve as a 3D substrate and current collector. The morphology of the sample was monitored with SEM during the fabrication process. Measured by electrochemical techniques, the material achieved a gravitational capacitance of 1601 F/g (∼80% of the theoretical value). A high power density up to 3 × 105 W/kg was confirmed, which is more than one magnitude higher than state of the art values. The reason for the high rate performance is also determined and discussed in detail, and fast ion diffusion inside the 3D composite is confirmed.

A combined layer structure of aluminum nitride (AlN) and silicon nitride (SixNy) enables the fabrication of multisegment piezo-actuated micro lenses with a precise control of the lens surface. It is demonstrated that these micro lenses offer free aspheric deformation of the lens surface and can operate at high repetition rates along with reproducible and precise tunability. The AlN/SixNy micro lenses are highly advantageous to be used as wave front filter or for fast focus correction.

The surface termination of single crystalline diamond with fluorine and chlorine was investigated. The diamond was exposed to SF6 inductively coupled plasma for fluorination and to Cl2 plasma for chlorination. For the fluorine termination, the plasma treatment caused one monolayer of fluorine (measured with two angle photoelectron detection) and no carbonyl fluorides on the diamond surface. Furthermore no graphitization or roughening of the surface was observed. The plasma treatment with chlorine led to rough surfaces.

Boron doped diamond (BDD) is a promising electrode material for electrochemical biosensor applications due to its low bio-fouling, chemical stability, and large potential window. For the first time, BDD nanoelectrode arrays (NEA) were studied using Scanning Electrochemical Microscopy (SECM) measurements. Using the phase-operated shear force technique and feedback mode, it was possible to scan a platinum (Pt) nanode with an active radius of 167nm over a diamond array at a constant distance of 45nm and to detect the electrochemical activity of single BDD nanodes in the 100nm range.

CVD diamond films with nitrogen content varying from 10 ppm to 132 ppm have been studied by electron spin resonance (ESR), light-induced ESR (LESR) as well as spin-dependent conductivity (SDC). Two characteristic signals have been observed. A carbon-related defect line with g = 2.0029 ± 0.0002 and width 4 ± 1 G, is observed in ESR, LESR and SDC. The intensity of this line measured by ESR increases linearly with nitrogen content. For low-defect-density samples, or after illuminating the high-defect-density samples with UV light, a second signal is observed both in ESR and LESR, but not in SDC, with a central line at g = 2.0024 ±0.001 and width 0.2 ± 0.1 G and related hyperfine satellites ≈30 G away from the central line. This line is assigned to isolated substitutional nitrogen, the so-called PI center. The density of N-related paramagnetic states is strongly affected by illumination and heat treatments. Spin-dependent conductivity measurements show that the dark conductivity at room temperature in CVD-diamond is dominated by hopping at the g = 2.0029 defects.

By using a Nd: YAG-pumped optical parametric oscillator (OPO) as excitation light source (8 ns pulse width), the dynamic range of photothermal deflection spectroseopy (PDS) is increased by a factor up to 1000. This enables the study of nonlinear defect absorption in intrinsic, phosphorus and boron doped a-Si:H. To probe nonlinear absorption of defects, the intensity of the fundamental emission of the Nd:YAG (1064 nm) has been varied over three orders of magnitude. For intensities greater than 1024 photons/ (cm2s), a significant increase of a by a factor 1.4 in p-, 1.2 in i-, and 1.15 in n-a-Si:H is detected. From electron spin resonance (ESR) and transient photoconductivity experiments on intrinsic a-Si:H, a bleaching of the defect density by electron excitation into the conduction band is measured. A hole-like signature in the ESR spectra indicates that electrons from the valence band are excited into the defect band as well. The data are interpreted based on a model for IR-induced nonlinear optical effects.

Optical and transport studies of both cb- and vb-tail states in a-Si1−xGex:H such as subband absorption (PDS), instationary photocurrent experiments (TOF, PTS) for electrons and holes, Modulated Photocurrent Spectroscopy (MPS), and Raman scattering have been performed. The main consequences of Ge-alloying into the a-Si:H network are i) an increase in cb-tail state density at the conduction band edge and in the exponential cb- tail even for small x (O0.35 into a Si-Ge compound structure with maximum disorder at x≈0.5.

We will report on the field emission properties of single crystal n-type cubic boron nitride (c-BN) for the first time. Vacuum annealed positive electron affinity (PEA) surface shows lower threshold voltages compared to H-terminated negative electron affinity (NEA) surface. An internal barrier height of c-BN surface with NEA was estimated to be 3.5 eV according to the Schottky barrier lowering model, which prevents electrons from approaching to the emitting surface. A higher electric field is required to reduce the internal barrier for emitting electrons compared to a small PEA surface. From the Fowler-Nordheim plots, the PEA was calculated to be about 0.6 eV, which dominates the electron emission from the vacuum annealed surface.

Nano-wires have become promising tools in a vast field of applications. Due to the many unique properties of diamond, the use of diamond nano-wires in biosensors attracts increasing attention. In this paper we introduce the realisation of wires from diamond using self-aligned nickel nano-particles as etching mask in an oxygen ICP dry etching step. With this process it is possible to create wires of high aspect ratios of 50, with diameters as small as 20 nm, and typical lengths of up to 1 μm on a large area in a dense pattern of about 1011 cm− 2. The Ni nano-particles are formed by thermal annealing at 700 °C for 5 min of a thin (1 nm) Ni film that is deposited onto the diamond surface. The surface enhancement factor due to wires is dependent on the geometrical details of wires and was measured to be 10 to 80. The electrochemical properties of wires have been characterized by cyclic voltammetry using Fe(CN)6− 3/− 4 which shows that such topographies act as filter for redox molecules.