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Boron-doped SiC thin films were deposited on N-type Si(100) substrates at various deposition conditions by means of HWCVD technology using silane (SiH4), methane (CH4), hydrogen(H2), dibora...

The carbon-based very thin films were deposited on silicon substrate and double side polished sapphire or quartz glass by RF reactive magnetron sputtering using a carbon target and gas mixtures Ar, N2 and H 2. Concentration of elements in the films was determined by RBS and ERD method simultaneously. SEM was used to investigate the morphology of carbon thin films. Raman spectroscopy was used for intensity ratios determination I(D)/I(G) of D and G peaks of carbon films. Photo-induced electron emission method was used for the study of electron emission properties of carbon-based very thin films. An examination of the results highlights how the technology and the structure of carbon films on quartz or sapphire glass play a key role in enhancing efficient escape of generated photoelectrons.

Amorphous silicon carbide films were prepared by PECVD technology on Si substrate with the aim to use SiC films in the technology of photoelectrochemical water splitting devices. Concentration of elements in the films was determined by RBS and ERD method. FTIR, Raman and I-V measurement were used before and after immersion of samples to aqueous sulfuric acid electrolyte. Differences between Raman or FTIR spectra and differences between I-V characteristics before and after immersion to electrolyte are discussed.

Amorphous silicon carbide in various forms, thin films or bulk structures, is a longer period used in microelectronics, power electronics, sensors and mechanical engineering. Thin films of n-doped amorphous silicon carbide (a-SiC:H) in combination with crystalline silicon representing heterostructure for the solar cells were object of this study. DC and AC measurements and subsequent analyzes were used to estimate the impact of Xe irradiation on electrical properties of studied heterostructure. Impact of Xe irradiation has been quantified by using AC equivalent circuit and the corresponding voltage dependence of AC equivalent circuit elements. The influence of Xe-ions bombardment of a-SiC:H/c-Si heterostructure which resulted in the changes of elements of equivalent circuit — parallel resistance and capacitance — have been identified and explained.

Photovoltaic heterostructures composed of thin film of p-doped amorphous silicon carbide a-SiC and thin films of n-doped crystalline silicon prepared by PECVD deposition technique were the object of this study. Prepared structures have been subjected to accelerated aging process at 85 °C in dry air, respectively under the influence of the different degrees of humidity. The electrical measurements and visual assessments of the samples were performed before the process of accelerated aging and after 25, resp. 90 days. Accelerated aging affects the electrical transport processes in the solar heterostructures. Slight increase in leakage resistance and capacity of the sample was detected in the case of dry heat. The effect of a 100 % humidity resulted in deteriorated performance of the sample. The destruction of the sample was observed in the case of sample immersed in the water. The complex impedance formalism and equivalent circuit were used to estimate the aging influences.

Nanocrystalline NiO thin films were deposited by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Au on a NiO film surface. Very thin Au overlayers with a thickness of about 1 and 7 nm have been prepared by magnetron sputtering. Then, the surface modified NiO films have been analysed by TEM, EDX and SEM. NiO thin films showed a polycrystalline structure with the size of nanocrystals ranging from a few nanometers to 10 nm. Electrical responses of NiO-based structure towards hydrogen have been measured.

Amorphous silicon carbide films were deposited by plasma enhanced chemical vapor deposition (PECVD) technology using SiH 4 , CH 4 , H 2 and NH 3 gas as precursors. The concentration of elements in the films was determined by RBS and ERD analytical method. Chemical compositions were analyzed by FT-IR spectroscopy. Raman spectroscopy study of the SiC films were performed by using a Raman microscope. Irradiation of samples with neutrons to fluencies A(7.9x10 14 cm -2 ), B(5x10 15 cm -2 ) and C(3.4x10 16 cm -2 ) was performed at room temperature. Raman spectroscopy results of SiC films showed decreasing of Raman band feature intensity after neutron irradiation and slightly decreased with increased neutron fluencies. Raman spectra differences between types of films before and after neutron irradiation are discussed. The electrical properties of SiC films were determined by the I-V measurement at 295 K. The measured currents were greater (about two order) after irradiation than the current before irradiation for all samples and rose up with neutron fluencies.

The plasma CVD reactor with parallel plate electrodes was used for plasma enhanced chemical vapor deposition (PECVD) of two type’s silicon carbide thin films on Si substrates. The concentration of elements in the films was determined by RBS and ERD analytical method simultaneously. The chemical compositions of the samples were analyzed by FTIR method. RBS and ERD results showed that the films contain silicon, carbon, hydrogen and small amount of oxygen. FTIR results confirmed the presence of Si-C, Si-H, C-H, and Si-O bonds. From the FTIR spectra the main following vibration frequencies were determined: the band from 2800 to 3000 cm-1 is attributed to stretching vibration of the CHn group in both the sp2 (2880 cm-1) and sp3 (2920 cm-1) configurations. The band at 2100 cm-1 is due to SiHm stretching vibrations. The band at 780 cm-1 can be assigned to Si-C stretching vibration. Main features of FTIR spectra were Gaussian fitted and detailed analyses of chemical bonding in SiC films were performed. Differences between two types of SiC films were discussed with the aim to using these films in the heterojunction solar cell technology.

Thin films of p-doped amorphous SiC used as an emitter layer for heterojunction solar cells have been the subject of this work. Thin amorphous SiC films were prepared by PECVD technology. Impact of dopation on the resulting properties of heterojunction was the main object of this study. The DC measurements under dark were performed in order to detect basic electronic properties as a diode ideality factor and saturation current. PV parameters such as fill factor, open circuit voltage and efficiency were obtained from DC measurements under illumination. The impedance spectroscopy analysis was performed by following Cole-Cole principle.

Nanostructured NiO thin films were prepared by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Pt on an NiO film surface. Pt very thin overlayers with a thickness of about 3 and 5 nm have been deposited by magnetron sputtering. The microstructure and surface morphology of the samples have been analysed by XRD and by SEM and AFM, respectively. The electrical responses of the NiO-based sensors towards hydrogen concentration have been also considered. The thickness of the Pt thin layers seems an important parameter in determining the properties of the NiO films as hydrogen sensors.

Nanocrystalline NiO thin films were prepared by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Pt on an NiO film surface. Very thin Pt overlayers with a thickness of about 3 and 5 nm have been deposited by magnetron sputtering. Then, the modified NiO films have been analyzed by TEM, EELS and AES. NiO thin films showed a polycrystalline structure (fcc NiO phase) with the size of nanocrystals ranging from a few nanometres to 10 nm. TEM observations both of unmodified and Pt-modified NiO films revealed that they were formed by nanocrystals and an amorphous phase. Uniformly distributed Pt particles were produced on top of the NiO surface. According to AES measurements, the presence of Ni in the spectra recorded from Pt pad indicated that the Pt layer has discontinuous nature. Electrical responses of NiO-based sensor structures towards hydrogen have been measured.

Nickel oxide (NiO) thin films were prepared by DC reactive magnetron sputtering from a nickel metal target in an Ar+O 2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15 to 45%. The films deposited in the metal-sputtering mode at a high target voltage (320–326 V) resulted in a polycrystalline (fcc) NiO phase with nearly stoichiometric composition. On the contrary, the films prepared in the oxide-sputtering mode at a low target voltage (293–298 V) were amorphous and oxygen rich. All examined NiO films were semiconductors and their conductance increased by four orders of magnitude between 25 and 350°C. Finally, NiO films were tested in order to investigate their response to NH 3 at various operating temperatures.

Nickel oxide (NiO) thin films were prepared by dc reactive magnetron sputtering from a nickel metal target in an Ar+O2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15% to 45%. The films prepared in the oxide-sputtering mode were amorphous while the films in metal-sputtering mode exhibited polycrystalline (fcc) NiO phase. In this case TEM observations showed a dense fine-grained structure with the grain size in the range 4–10 nm and AFM micrograph showed a rough surface with RMS=2.21 nm. We have found that good NiO stoichiometric films are obtainable with a polycrystalline (fcc) structure at 40% oxygen content in the metal-sputtering mode.

Nickel oxide (NiO) thin films were prepared on Si substrates by DC reactive magnetron sputtering from a nickel metal target in Ar+O2 with the relative O2 content varied from 15 to 50%. The effects of the O2 gas content on the deposition rate, structure, composition and electrical properties were investigated. NiO stoichiometric films were obtained with a polycrystalline structure and a specific resistivity of near 300 Ωcm at 25% O2 content in the discharge gas. Film composition and structure, and this resistivity, were dependent on the discharge parameters. Thus the deposited films had amorphous and polycrystalline structures with Ni\O ratio ranges between 0.71 and 1.02 as a function of the discharge O2 content.

The thermal stability of physical, chemical, and electrical properties of magnetron-deposited NbN thin films on GaAs were investigated. A variety of characterization methods, including Auger analysis, Rutherford backscattering spectrometry analysis, and Schottky barrier measurement showed that the NbN\GaAs interface remains stable after rapid thermal annealing at 850°C for 10 s for NbN films prepared at a 2 and 5% nitrogen content in working gas mixture. It was found that the best electrical parameters (barrier height 0.77 eV and ideality factor 1.11) of NbN\GaAs Schottky contacts were measured for the highest annealing temperature (900°C, 10 s) and the lowest nitrogen content (2%) in working gas mixture.

Niobium nitride films were prepared on unheated GaAs substrates by dc reactive magnetron sputtering from a niobium metal target in an Ar + N2 mixed atmosphere. The nitrogen content in the gas mixture was varied from 2–20%, and the structural and electrical characteristics of the deposited thin NbN Schottky contacts to GaAs studied under high-temperature annealing (with annealing temperatures ranging from 850–950 °C). Using several characterisation methods, Auger analysis, Rutherford backscattering spectrometry analysis, and Schottky barrier measurement, it was found that the NbN/GaAs interface remained stable after rapid thermal annealing at 900 °C for 10 s for NbN films prepared with 2 and 5% N2 in the gas mixture.

Silicon carbide films were deposited on n-type Si substrates (111) of resistivity 2–7 Ω cm in a high-frequency parallel-plate plasma reactor. The deposition temperatures were 250, 350 and 450 °C, respectively. The RBS results showed that the concentrations of Si and C in the films depend a little on the deposition temperature. The films contain a small amount of oxygen and nitrogen. IR results showed the presence of Si–C, Si–H, C–H, Si–O, Si–N specific bonds. The AFM micrographs revealed that the film surface is rather smooth and compact.

The influence was investigated of N-doped diamond-like carbon (DLC) films properties on the quantum efficiency of a prepared transmission photocathode. N-doped DLC thin films were deposited on a silicon substrate, a stainless steel mesh and quartz glass (coated with 5 nm thick Cr adhesion film) by reactive magnetron sputtering using a carbon target and gas mixture Ar, 90%N2+10%H2. The elements' concentration in the films was determined by RBS and ERD. The quantum efficiency was calculated from the measured laser energy and the measured cathode charge. For the study of the vectorial photoelectric effect, the quartz type photocathode was irradiated by intensive laser pulses to form pin-holes in the DLC film. The quantum efficiency (QE), calculated at a laser energy of 0.4 mJ, rose as the nitrogen concentration in the DLC films was increased and rose dramatically after the micron-size perforation in the quartz type photocathodes.

Silicon carbon nitride films were grown at various deposition temperature from 350 to 550 °C by means of electron cyclotron resonance (ECR) plasma deposition with gas mixture: 5% SiH 4 in N 2 (20 sccm), CH 4 (10 sccm). A p-type silicon wafer with resistivity 2–7 Ωcm and (100) orientation was used as the substrate for the SiCN films. The concentration of elements in the SiCN films was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method simultaneously. Chemical compositions were analysed by infrared (IR) spectroscopy. Photoluminescence (PL) spectra were measured at 293 K. The concentration of hydrogen was decreased with increasing deposition temperature. The IR results showed the presence of Si-C, Si-N, Si-H, C-H, C-N, N-H and Si-O bonds. The PL results showed increassing PL intensity with increasing a sample deposition temperature from 350 to 450 °C and decreasing PL intensity with increasing a sample deposition temperature from 450 to 550 °C.

Silicon carbide films were deposited at two deposition temperatures 350 ° C and 450 ° C by means of ECR plasma reactor with two gas mixtures: (1) gas mixture, SiH 4 (5 sccm), CH 4 (14 sccm), Ar (6 sccm), NH 3 (2 sccm) and (2) gas mixture SiH 4 (5 sccm), CH 4 (14 sccm), H 2 (6 sccm), NH 3 (2 sccm). The concentration of species in the SiC films was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method simultaneously. Chemical compositions were analyzed by infrared (IR) spectroscopy. Photoluminescence (PL) spectra were measured at 300 K. The RBS and ERD results showed that the concentrations of Si and C in the films are practically the same. The concentration of hydrogen decreased from 30 to 22 at.% with an increasing sample deposition temperature. The films contain a small amount of nitrogen and oxygen. IR results showed the presence of Si-C, Si-N, Si-H, C-H and Si-O bonds. PL results showed the decrease of the PL intensity with an increasing sample deposition temperature.

A capacitively coupled plasma reactor was used for PECVD technology, where methane was introduced into the plasma reactor through the shower head. The concentration of species in the a-C:H films were determined by RBS and ERD method. The RBS results showed the main concentrations of C in the films. The concentration of hydrogen was approximately 20 at.%. The films contain a small amount of oxygen and nitrogen. Chemical compositions were analyzed by IR spectroscopy. IR results showed the presence of C-H specific bonds.

Thin silicon carbide (SiC) films were prepared by plasma enhanced chemical vapour deposition (PECVD). The structural properties of SiC films were investigated by IR, RBS, and ERD measurement techniques. The results showed that the films contain the typical features found in hydrogenated amorphous SiC. The I-U measurements were used to electrical characterization of Au Schottky contacts prepared on SiC surfaces.

Elastic recoil detection method was applied for the study of hydrogen in silicon nitride as well as silicon oxynitride thin films. For this purpose 2.4 MeV 4 He + ions produced by the Van de Graaff accelerator of JINR have been used. The thin films have been prepared by the electron cyclotron resonance plasma deposition technique. The physical properties of these layers, which play an important role in the technology of semiconductor devices, are strongly dependent on the amount of hydrogen incorporated during their deposition. The technique of the hydrogen depth determination by ERD is very important for the optimization of process parameters of the ECR plasma deposition of the silicon (oxy)nitride layers with optimal physical and electrical properties.

The properties of hydrogenated amorphous silicon carbide films prepared by plasma enhanced chemical vapour deposition were studied by combination of infrared (IR), RBS, ERD (elastic recoil detection) measurement. IR result shoved the presence Si-C, Si-H, C-H bonds. The compositions of the silicon, carbon and hydrogen in the films were found to be dependent on the preparation conditions.

Nickel oxide (NiO) thin films were prepared on Si substrates by dc reactive magnetron sputtering from a nickel metal target in Ar+O/sub 2/ with O/sub 2/ content varied from 15 to 50%. The effects of the O/sub 2/ gas content on the deposition rate, structure, composition and electrical properties were investigated. We have found that the good NiO stoichiometric films are obtainable with a polycrystalline structure and a resistivity of near 300 /spl Omega/cm at 25% oxygen content. But either the resistivity or the composition and structure suffer variations with the discharge parameters. Depending on the oxygen content, the deposited films have both amorphous and polycrystalline structures and the Ni/O ratio ranges between 0.71 and 1.02.

The properties of nitrogen-doped amorphous SiC films irradiated by pulsed electron beams are presented. The I-V characteristics of diodes made of irradiated SiC films grown on silicon substrates were investigated. The results showed that the film conductivity increased by about two orders of magnitude as nitrogen fraction was increased from 10 at% to 14 at%. The film conductivity was enhanced by about one order of magnitude as a result of two-fold increase of pulsed electron beam irradiation.

Nanocrystalline silicon carbide was prepared by PECVD technology in capacitively parallel plate plasma reactor, where both silane and methane were introduced into the plasma reactor. The concentration of species in the SiC films was determined by RBS and ERD. Chemical compositions were analyzed by IR spectroscopy. Film morphology was assessed by AFM. The RBS results showed the main concentrations of Si and C in the films. The concentration of hydrogen was approximately 20 at.%. IR results showed the presence of Si-C, Si-O, Si-N, Si-H, N-H, C-H, C-N specific bonds. The AFM micrographs revealed the film surface smooth and compact. Results of I-V measurements before and after samples irradiation by neutrons are presented.