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Herein we investigated hydrophilic surface modification of SiOx containing amorphous hydrogenated carbon nanocomposite films (DLC:SiOx) via the use of atmospheric oxygen plasma treatment. The modified films exhibited effective hydrophilic properties with complete surface wetting. More detailed water droplet contact angle (CA) measurements revealed that oxygen plasma treated DLC:SiOx films maintained good wetting properties with CA of up to 28 ± 1° after 20 days of aging in ambient air at room temperature. This treatment process also increased surface root mean square roughness from 0.27 nm to 1.26 nm. Analysis of the surface chemical states suggested that the hydrophilic behavior of DLC:SiOx treated with oxygen plasma is attributed to surface enrichment with C–O–C, SiO2, and Si–Si chemical bonds as well as significant removal of hydrophobic Si–CHx functional groups. The latter functional groups are prone to restoration and are mainly responsible for the increase in CA with aging. Possible applications of the modified DLC:SiOx nanocomposite films could include biocompatible coatings for biomedical applications, antifogging coatings for optical components, and protective coatings to prevent against corrosion and wear.

Graphene was synthesized directly on Si(100) substrates by microwave plasma-enhanced chemical vapor deposition (MW-PECVD). The effects of the graphene structure on the electrical and photovoltaic properties of graphene/n-Si(100) were studied. The samples were investigated using Raman spectroscopy, atomic force microscopy, and by measuring current–voltage (I-V) graphs. The temperature of the hydrogen plasma annealing prior to graphene synthesis was an essential parameter regarding the graphene/Si contact I-V characteristics and photovoltaic parameters. Graphene n-type self-doping was found to occur due to the native SiO2 interlayer at the graphene/Si junction. It was the prevalent cause of the significant decrease in the reverse current and short-circuit current. No photovoltaic effect dependence on the graphene roughness and work function could be observed.

Chemical vapor deposition (CVD) is an attractive technique which allows graphene with simultaneous heteroatom doping to be synthesized. In most cases, graphene is grown on a catalyst, followed by the subsequent transfer process. The latter is responsible for the degradation of the carrier mobility and conductivity of graphene due to the presence of the absorbants and transfer-related defects. Here, we report the catalyst-less and transfer-less synthesis of graphene with simultaneous nitrogen doping in a single step at a reduced temperature (700 °C) via the use of direct microwave plasma-enhanced CVD. By varying nitrogen flow rate, we explored the resultant structural and chemical properties of nitrogen-doped graphene. Atomic force microscopy revealed a more distorted growth process of graphene structure with the introduction of nitrogen gas—the root mean square roughness increased from 0.49 ± 0.2 nm to 2.32 ± 0.2 nm. Raman spectroscopy indicated that nitrogen-doped, multilayer graphene structures were produced using this method. X-ray photoelectron spectroscopy showed the incorporation of pure pyridinic N dopants into the graphene structure with a nitrogen concentration up to 2.08 at.%.

In this research, the graphene was grown directly on the Si(100) surface at 600 °C temperature using an anode layer ion source. The sacrificial catalytic cobalt interlayer assisted hydrocarbon ion beam synthesis was applied. Overall, two synthesis process modifications with a single-step graphene growth at elevated temperature and two-step synthesis, including graphite-like carbon growth on a catalytic Co film and subsequent annealing at elevated temperature, were applied. The growth of the graphene was confirmed by Raman scattering spectroscopy and X-ray photoelectron spectroscopy. The atomic force microscopy and scanning electron microscopy were used to study samples’ surface morphology. The temperature, hydrocarbon ion beam energy, and catalytic Co film thickness effects on the structure and thickness of the graphene were investigated. The graphene growth on Si(100) by two-step synthesis was beneficial due to the continuous and homogeneous graphene film formation. The observed results were explained by peculiarities of the thermally, ion beam, and catalytic metal activated hydrocarbon species dissociation. The changes of the cobalt grain size, Co film roughness, and dewetting were taken into account.

In this study, graphene was synthesized on the Si(100) substrates via the use of direct microwave plasma-enhanced chemical vapor deposition (PECVD). Protective enclosures were applied to prevent excessive plasma etching of the growing graphene. The properties of synthesized graphene were investigated using Raman scattering spectroscopy and atomic force microscopy. Synthesis time, methane and hydrogen gas flow ratio, temperature, and plasma power effects were considered. The synthesized graphene exhibited n-type self-doping due to the charge transfer from Si(100). The presence of compressive stress was revealed in the synthesized graphene. It was presumed that induction of thermal stress took place during the synthesis process due to the large lattice mismatch between the growing graphene and the substrate. Importantly, it was demonstrated that continuous horizontal graphene layers can be directly grown on the Si(100) substrates if appropriate configuration of the protective enclosure is used in the microwave PECVD process.

Diamond like carbon films containing silicon (DLC:SiOx) and "conventional" hydrogenated diamond like carbon (DLC) films were deposited by direct ion beam using anode layer ion source. Ag films were grown by unbalanced direct current magnetron sputtering. Structure of DLC:SiOx films was investigated by Raman scattering spectroscopy. In the case of DLC:SiOx film deposited on Ag layer surface enhanced Raman scattering effect was observed. Optical properties of the different diamond like carbon and silver multilayers were studied. Annealing effects were investigated. Influence of the thickness of the diamond like carbon and Ag layers was investigated. Position of the plasmonic absorbance peak maximum of DLC:SiOx and multilayers in all cases was redshifted in comparison with "conventional" diamond like nanocomposite films containing silver nanoclusters. It was explained by increase of the Ag nanoparticle size and/or increased probability of the oxidation of the embedded Ag due to the higher amount of oxygen in DLC:SiOx film in comparison with "conventional" diamond like carbon film.

The present article reviews current situation on SiOx containing diamond like carbon (diamond like nanocomposite) films. The overview of different deposition methods and reagents used is presented; chemical composition of different diamond like nanocomposite films is described. Different models of structure of diamond like nanocomposite films are considered. Mechanical, optical, electrical properties as well as surface energy of diamond like nanocomposite films produced by different methods are reviewed and discussed. The survey of different potential and industrial applications of diamond like nanocomposite films is presented., Straipsnyje apžvelgiama dabartinė būklė nanokompozicinių deimanto tipo anglies plėvelių (SiOx turinčių deimanto tipo anglies dangų) tyrimų srityje. Aptariami įvairūs šių dangų formavimo metodai bei sintezei naudojamos medžiagos. [...]

In the present research ion energy effects on piezoresistive properties of hydrogenated diamond like carbon (DLC) films deposited by hydrocarbon ion beam deposition and radio frequency plasma enhanced chemical vapor deposition (PECVD) were studied. Comparative analysis of the influence of silicon oxide and silicon doping on gauge factor of DLC films was performed. Only weak dependence of piezoresistive properties of the DLC films deposited from acetylene gas by ion beam deposition using closed drift ion source on ion energy was observed and that was explained as a result of the competing effects of ion energy and ion/neutral ratio during the diamond like carbon film deposition process. In the case of PECVD deposited DLC films the dependence of gauge factor on substrate bias was observed. Doping by silicon and silicon oxide resulted in decrease of the DLC film gauge factor. Possible relations between the gauge factor of DLC films and their optical parameters such as optical bandgap, Urbach energy and B parameter were studied as well. It was found, that the gauge factor increases with the increased separation between valence and conduction π band in DLC films and/or decrease size of sp2 cluster as well as with the decrease of the topological disorder (range in which vary size of sp2 clusters) and/or density of sp2 states and ammount of sp2 bonded carbon phase. Resistivity of the investigated DLC films deposited by both methods decreased with the increase of the ion energy and no correlation between the piezoresistive properties of DLC films and their resistance was found. The observed behavior was explained by dependence of resistivity on hydrogen ammount in DLC films. Keywords: diamond like carbon films, piezoresistance, optical properties., Šiame darbe tirta jonų energijos įtaka hidrogenizuotų deimantiškųjų anglies dangų (DAD), susintetintų angliavandenilių jonų pluošteliu bei radijo dažnio plazma aktyvinto cheminio nusodinimo iš garų fazės būdu, pjezovaržinėms savybėms. Nagrinėtas legiravimo silicio oksidu bei siliciu poveikis DAD pjezovaržiniam keitimo veiksniui. Maža jonpluoštės sintezės būdu nusodintų DAD pjezovaržinių savybių priklausomybė nuo sintezei naudoto jonų pluoštelio energijos susijusi su konkuruojančia jonų energijos ir jonų bei neutraliųjų atomų santykio įtaka. Šiuo atveju bandinių keitimo veiksnys buvo 11-21, o plazma aktyvinto cheminio nusodinimo iš garų fazės būdu nusodintų DAD pjezovaržinės savybės priklausė nuo priešįtampio įtampos, kuri yra tiesiog proporcinga jonų energijai. Dangų, nusodintų naudojant –400V priešįtampį, didžiausias keitimo veiksnys buvo 41± 17. Ištyrus legiravimo siliciu ir silicio oksidu įtaką pjezovaržinėms DAD savybėms, nustatyta, kad tokio tipo legiravimas mažina pjezovaržinį keitimo veiksnį. 2% silicio legiruotų DAD keitimo veiksnys buvo 9,7± 1,28, o silicio oksido turinčių DAD pjezovaržinis keitimo veiksnys buvo 3,5-6. Šiame darbe taip pat tirta galima pjezovaržinių ir optinių DAD savybių (optinės draustinės juostos pločio, B parametro ir Urbacho energijos) tarpusavio koreliacija. Nustatyta, kad keitimo veiksnys didėja didėjant tarpui tarp valentinės ir laidumo p juostų DAD, sumažėjus sp2 klasterių matmenims bei topologinei netvarkai ir(arba) sp2 būsenų tankiui ir sp2 ryšiais sujungtų anglies atomų skaičiui. DAD savitoji varža mažėjo didėjant auginimui naudojamų jonų energijai. Jokios koreliacijos tarp deimantiškųjų anglies dangų pjezovaržinių savybių ir varžos nebuvo pastebėta. [...]

In present study four newly synthesized organic semiconductor compounds have been used for fabrication of the planar metal / organic semiconductor / metal structures. I-V characteristics of the samples were investigated. Effect of the hysteresis of the I-V characteristics was observed for all samples investigated. However, strength of the hysteresis depended on organic semiconductor used. Charge transfer mechanisms were considered. In all cases the main charge transfer mechanism was trap activated tunneling. Yet at higher electric fields Schottky emission should be considered as well., Šiame darbe tirtos metalo-organinio puslaidininkio-metalo darinių elektrinės charakteristikos. Naudoti šie organiniai puslaidininkiai: 4,4'-diformyltrifenylamino bis(N-2,3-epoksipropyl-N-fenylhydrazonas (toliau MT-12), di(2,2-difenylvinyl)(9-etyl-3-karbazolyl)aminas (toliau E-139), 4-difenylaminobenzaldehydo N-metyl-N-fenylhydrazonas (toliau AT-RB-1), 4-difenylaminobenzaldehydo N,N-difenylhydrazonas (toliau AT-RB-2). Kaip kontaktų (elektrodų) metalas naudoti Al, Au, Cr, Ti. Nustatyta, kad visų bandinių, suformuotų naudojant organinius puslaidininkius MT-12, AT-RB-1, kaitintą ore AT-RB-1, E-139, VACh yra būdinga histerezė. Didžiausia histereze ir didžiausiomis srovėmis pasižymi bandiniai, suformuoti naudojant E-139, mažiausia histereze ir mažiausiomis srovėmis – bandiniai suformuoti naudojant organinį puslaidininkį MT-12. Iš visų tirtų organinių puslaidininkių išsiskyrė AT-RB-2. Apie jam būdingus kokius nors dėsningumus sunku ką pasakyti, nes visais atvejais VACh sklaida yra didelė. Išnagrinėjus galimus krūvio pernašos bandiniuose mechanizmus nustatyta, kad pagrindinis krūvio pernašos mechanizmas yra gaudyklėmis suaktyvintas tuneliavimas. Esant didesnėms įtampoms (didesniems elektrinio lauko stipriams), įtakos gali turėti ir Schottky emisija (termoelektroninė emisija). Išnagrinėjus metalo-organinio puslaidininkio-metalo (metalinis elektrodas virš organinio puslaidininkio) darinių VACh histerezę ± 200 V diapazone, nustatyta, kad, mažinant įtampą, nuo –200 V bandiniu iš pradžių teka gaudyklių apribota tunelinė srovė, kuri, pakeitus įtampos poliškumą, pereina į mišrią gaudyklių apriboto tuneliavimo ir termoelektroninės emisijos srovę. [...]