J. Huran

Properties of amorphous silicon carbide films prepared by PECVD

Abstract Amorphous SiC was prepared by plasma enhanced chemical vapour deposition of SiH 4 and CH 4 . The properties of the SiC deposits were studied using a combination of infrared (IR), RBS, ERD (electron recoiling detection) and AES measurement. Infra red spectra showed the presence of SiC, SiH and CH bonds. The compositions of the silicon, carbon and hydrogen in the films were found to be dependent on the preparation conditions.

Application of the ERD method for hydrogen determination in silicon (oxy) nitride thin films prepared by ECR plasma deposition

Abstract 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.

Study of the d(p, γ)3He reaction at ultralow energies using a zirconium deuteride target

Abstract The mechanism for the d ( p , γ ) 3 He reaction in the region of ultralow proton–deuteron collision energies (6.67 E S -factor and the effective pd reaction cross section on the proton–deuteron collision energy are measured. The results are compared with the available literature data. The results of this work agree with the experimental results obtained by the LUNA collaboration with the target of gaseous deuterium.

Investigation of temperature dependence of neutron yield and electron screening potential for the d(d, n)3He reaction proceeding in deuterides ZrD2 and TiD2

The temperature dependence of the enhancement factor for the dd reaction proceeding in TiD2 and ZrD2 is investigated. The experiments were carried out at the Hall pulsed ion accelerator (INP, Polytechnic University, Tomsk, Russia) in the deuteron energy interval 7.0–12.0 keV and at temperatures ranging from 20 to 200°C. The values obtained for the electron screening potentials indicate that the dd reaction enhancement factor does not depend on the target temperature in the range 20–200°C. This result contradicts the conclusions drawn by the LUNA Collaboration from their work.

HYDROGENATED AMORPHOUS SILICON CARBON NITRIDE FILMS PREPARED BY PECVD TECHNOLOGY: PROPERTIES

Hydrogenated amorphous silicon carbon nitride films were grown by plasma enhanced chemical vapor deposition (PECVD) technique. The flow rates of SiH4 , CH4 and NH3 gases were 6 sccm, 30 sccm and 8 sccm, respectively. The deposition temperatures were 350, 400 and 450 ◦C. The RBS and ERD results showed that the concentrations of Si, C, N and H are practically the same in the films deposited at substrate temperatures in the range 350-450 ◦C. In photoluminescence spectra we identified two peaks and assigned them to radiative transitions typical for amorphous materials, ie band to band and defect-related ones. The electrical characterization consists of I(V ) measurement in sandwich configuration for voltages up to 100 V. From electrical characterization, it was found that with increased deposition temperature the resistivity of the amorphous SiCN film was reduced.

Measurement of astrophysical S factors and electron screening potentials for d ( d, n ) 3 He reaction In ZrD 2 , TiD 2 , D 2 O, and CD 2 targets in the ultralow energy region using plasma accelerators

The paper is devoted to study electron screening effect influence on the rate of d(d, n)3He reaction in the ultralow deuteron collision energy range in the deuterated polyethylene (CD2), frozen heavy water (D2O) and deuterated metals (ZrD2 and TiD2). The ZrD2 and TiD2 targets were fabricated via magnetron sputtering of titanium and zirconium in gas (deuterium) environment. The experiments have been carried out using high-current plasma pulsed accelerator with forming of inverse Z pinch (HCEIRAS, Russia) and pulsed Hall plasma accelerator (NPI at TPU, Russia). The detection of neutrons with energy of 2.5MeV from dd reaction was done with plastic scintillation spectrometers. As a result of the experiments the energy dependences of astrophysical S factor for the dd reaction in the deuteron collision energy range of 2–7 keV and the values of the electron screening potential Ue of interacting deuterons have been measured for the indicated above target: Ue(CD2) ⩽ 40 eV; Ue(D2O) ⩽ 26 eV; Ue(ZrD2) = 157 ± 43 eV; Ue(TiD2) = 125±34 eV. The value of astrophysical S factor, corresponding to the deuteron collision energy equal to zero, in the experiments with D2O target is found: Sb(0) = 58.6 ± 3.6 keV b. The paper compares our results with other available published experimental and calculated data.

Thermal stability of NbN films deposited on GaAs substrates

Abstract 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.

Effect of the crystal structure of a deuterated target on the yield of neutrons in the dd reaction at ultralow energies

The energy dependence of the neutron yield in the d(d, n)3 He reaction proceeding in a textured titanium deuteride target with the preferred orientation of microcrystals in the [100] direction has been studied. Measurements have been performed for the energy range of incident deuterons of 7–12 keV in the laboratory system. It has been shown that the energy dependence of the enhancement factor of the reaction is described not only by the screening potential but also by the simple inclusion of channeling effects.

Electrical properties of semi-insulating GaAs irradiated with neutrons

Conductivity, Hall mobility and magnetoresistance in undoped semi-insulating GaAs samples irradiated by reactor neutrons of various fluences ranging from 1×1013 to 3×1015 cm−2 were measured and analysed in the temperature range 300–420 K. The conductivity and the apparent Hall mobility decrease while the magnetoresistance increases with increasing neutron fluence. The ratio of electron to hole concentration (n/p), resulting from the analysis of the room temperature parameters using a mixed conductivity model, decreases with increasing neutron fluence and reaches value less than one at the highest fluences used. Activation energy ≈0.78 eV was found for dominant deep acceptor deduced from the temperature dependences of the free charge carriers concentration in samples with n/p<1. A role of the thermal neutrons shielding at the irradiation, using a Cd-plate, is discussed.

Preparation of hydrogenated amorphous silicon carbide thin films by plasma enhanced chemical vapour deposition

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.