Nanodiamonds (NDs) represent a novel nanomaterial applicable from biomedicine tospintronics. Here we study ability of air annealing to further decrease thetypical 5 nm NDs produced by detonation synthesis. We use atomic forcemicroscopy (AFM) with sub-nm resolution to directly measure individualdetonation nanodiamonds (DNDs) on a flat Si substrate. By means of particleanalysis we obtain their accurate and statistically relevant size distributions.Using this approach, we characterize evolution of the size distribution as afunction of time and annealing temperature: i) at constant time (25 min) withchanging temperature (480, 490, 500°C) and ii) at constant temperature(490°C) with changing time (10, 25, 50 min). We show that the mean sizeof DNDs can be controllably reduced from 4.5 nm to 1.8 nm without noticeableparticle loss and down to 1.3 nm with 36% yield. By air annealing the sizedistribution changes from Gaussian to lognormal with a steep edge around 1 nm,indicating instability of DNDs below 1 nm.

We investigated the fabrication of diamond-like carbon (DLC) emitter patterns byroom-temperature curing nanoimprint lithography (RTC-NIL) withpolydimethylsiloxane (PDMS) molds using polysiloxane, as an application to theemitter for the next generation flat panel display.

The DLC which has excellent properties similar to diamond properties was used asa pattern material. A PDMS was used as a mold material and fabricated by thefollowing optimum conditions of the first curing time at RT for 36 h and thesecond curing time at the temperature of 150 °C for 15 mins. Thepolysiloxane is in the state of sticky liquid at RT and stable in air.Therefore, the polysiloxane was used the electron beam (EB) resist and oxidemask material in EB lithography, and also used as RT-imprint material.

First, we fabricated the PDMS mold with pit array. Each dot is 5µm-diameter and 400 nm-depth. We carried out the RTC-NIL process withPDMS molds using polysiloxane under the following optimum imprint conditions of0.5 MPa-imprinting pressure, 1.5 min-the time between spin-coat and imprint, and5 min-imprinting time. Next, the residual layer of imprinted polysiloxanepattern was 450 nm and then was removed with electron cyclotron resonance (ECR)trifluoromethane (CHF3) ion shower under the conditions of 300 eV-ionenergy and 3 min-etching time. Then, we processed the imprinted polysiloxanepatterns on the DLC film with an ECR oxygen (O2) ion shower under theconditions of 400 eV-ion energy and 12 min-etching time. As a result, wesucceeded in fabricating convex DLC emitter patterns with high accuracy whichhas 5 µm-diameter and 500 nm-height.

Secondary electron transmission measurements are used to examine the electrondiffusion and thermalization processes in B-doped nanocrystalline diamondmembranes of thickness 2.3 μm and 650 nm. Specifically, transmittedenergy spectra are measured following impact by an electron beam that penetratesdeeper in the membrane as the beam energy Eo increases. Afully-thermalized emission peak is observed for Eo ≤ 16keV and Eo ≤ 7 keV from the 2.3-μm-thick and650-nm-thick films, respectively, with a small high-energy tail beginning toemerge at higher Eo. These measurements are analyzed using MonteCarlo simulations that generate constant-energy contour lines (down to 0.05Eo) as a function of beam depth into the film. From thesesimulations, we deduce that secondary electrons have a minimum thermalizationlength of ∼ 630 nm and ∼ 260 nm in the2.3-μm-thick and 650-nm-thick films, respectively. Further insightinto the secondary-electron transport behavior is gained from the analysis, andthis understanding is applied to the design of a transmission electron-currentamplifier device.

Boron doped nanocrystalline diamond films (BDND) were grown on reticulatedvitreous carbon (RVC) heat treated at 1000 and 1700 °C. Silver (Ag)nanoparticles were electrodeposited on RVC and RVC/BDND composites bypotentiostatic reduction of AgNO3 solution. The samples werecharacterized by scanning electron microscopy, Raman spectroscopy, X-raydiffraction, and cyclic voltammetry. The samples conductivities influenced theAg deposition amount as well as the Ag particle sizes where the smaller Agparticles were observed for RVC/BDND composites. The stability of Agnanoparticles was also confirmed by cyclic voltammetry.

An investigation of the electronic structure of charged vacancies and X(C),X=(As, Sb, P) substitutional centers in diamond has been carried out bymeans of ab initio density functional theory. The revisedHeyd-Scuseria-Ernzerhof screened hybrid functional (HSE06) was utilized for thetotal energy calculation. The equilibrium geometry, defect charge transitionlevels and energetics of the vacancies and substitutional centers weredetermined. It is found that substitutional As and Sb introduce a donor levelinto the band gap about 0.5 eV with respect to the conduction band minimum(CBM), therefore, these elements may be a good choice for achieving n-typediamond. From a technological point of view, however, fabrication of As and Sbdoped diamond would be challenging due to its high, positive formationenergy.

The performance of new type three dimensional buried-in electrode structureultraviolet photodetector fabricated on single crystal diamond epitaxial layerwas investigated. The epitaxial layer was grown onhigh-pressure-high-temperature Ib-type diamond substrate. Then the buried-inelectrodes with different depths were formed by oxygen plasma reactive ionetching method and radio frequency magnetron sputtering technique on thisdiamond layer. Compared with that of traditional planar electrode photodetector,the responsivity of buried-in electrode photodetector shows higher value, whichreaches the highest when the electrode depth is 100 nm.

Atomic force microscopy (AFM) is used to measure local electrical conductivity ofHPHT nanodiamonds (NDs) dispersed on Au substrate in the as-received state andafter thermal or plasma treatments. Oxygen-treated NDs are highly electricallyresistive, whereas on hydrogen-treated NDs electric current around -200 pA at -2V is detected. The as-received NDs as well as NDs after an underwaterradio-frequency (RF) plasma or laser irradiation (LI) treatments contain bothelectrically conductive (two types: highly and weakly conductive) and highlyresistive particles. The higher conductivity is attributed to H-terminated (RF)or graphitized (LI) NDs. The lower conductivity is attributed to NDs withhydrogenated amorphous carbon shell.

Diamond stands out among single-photon sources due to an intrinsically large bandgap, photo-stable emission, room-temperature operation, short excited statelifetimes, and the ability to host hundreds of different color centers.Currently, most of these centers are active in the optical spectrum, but asingle-photon source in the infrared would represent a significant advancement.In pursuit of this end, a number of different transition metal atoms have beenstudied as dopants in the diamond lattice via the GAMESS (General AtomicMolecular and Electronic Structure System) cluster calculation package. Theimportance of cluster size and electron correlation effects is considered, andexcitation energies have been calculated via time-dependent density functionaltheory.

We investigated the fabrication of convex diamond-like carbon (DLC) basedmicrogears in room-temperature curing nanoimprint lithography (RTC-NIL) usingthe ladder-type hydrogen silsesquioxane (HSQ), as an application for the medicalmicro electro mechanical system (MEMS). The HSQ which is an inorganic polymer ofsol-gel system turns into a gel when exposed to air and has the siloxane bond.Therefore, the HSQ was used as RT-imprinting material, and also used as an oxidemask material in electron cyclotron resonance (ECR) oxygen (O2) ionshower etching. We fabricated the polydimethylsiloxane (PDMS) mold with concavemicrogear patterns which has 40, 50 and 60 μm-tip diameter and 300nm-depth. We carried out the RTC-NIL process using the PDMS mold under thefollowing optimum conditions of 0.10 MPa-imprinting pressure and 1.0min-imprinting time. We found that the residual layer of imprinted HSQ microgearpatterns was removed with ECR trifluoromethane (CHF3) ion showerunder the following conditions of 300 eV-ion energy and 2.0 min-etching time,and then microgears of the HSQ on the DLC film were etched with ECRO2 ion shower under the following conditions of 400 eV-ion energy and10 min-etching time. As a result, the convex DLC based microgears which have 40,50 and 60 μm-tip diameter and 400 nm-height were fabricated with highaccuracy in the new fabrication process of RTC-NIL.

Schottky properties of Mo on diamond with fluorine- and oxygen-termination hadbeen investigated. Oxygen-termination was generated by aqua regia.Fluorine-termination was generated by CF4 plasma treatment. Mo/Ni/Auwas deposited on the diamond surface as Schottky electrode, whose barrier heightwas evaluated from current-voltage curve. After that, the X-ray photoelectronspectroscopy methods were applied to calculate the Schottky barrier height of Moon different termination surface. The results indicated that thefluorine-termination and oxygen-termination show different schottkyproperties.

Boron Doped Diamond (BDD) electrodes exhibit excellent properties including awide potential window in aqueous media, high corrosion resistance, chemicalinertness, bio-compatibility and low background current. In order to increasetheir selectivity for analytical applications, several studies were carried outrecently on the possibility to deposit metal nanoparticles such as Pt or Ir onsuch BDD electrodes1,2,3,4. Indeed these nanoparticles bringinteresting electro-catalytic properties to the electrodes, thus offering thepossibility to address new analytes. Here an electrode array was developed,based on multiple BDD electrodes casted with various metal nanoparticles. Thesimultaneous detection of analytes by each electrode composing the array givespotentially a unique fingerprint to the analytes, thus increasing thespecificity and the selectivity of the sensor.