Journal of Theoretical and Applied Physics (JTAP) The experimental approach into the influence of external inductance on the discharge characteristic of HiPIMS Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 The experimental approach into the influence of external inductance on the discharge characteristic of HiPIMS 10.1007/s40094-019-00347-3 EN Saeed Ghasemi Laser and Plasma Research Institute, Shahid Beheshti University, Evin, Tehran 1983963113, Iran Pourya Seyfi Laser and Plasma Research Institute, Shahid Beheshti University, Evin, Tehran 1983963113, Iran Alireza Farhadizadeh Laser and Plasma Research Institute, Shahid Beheshti University, Evin, Tehran 1983963113, Iran Hamid Ghomi Laser and Plasma Research Institute, Shahid Beheshti University, Tehran, Iran 0000-0003-2203-5194 Journal Article 2023 11 17 AbstractThe main objective of the current paper is to describe the effect of external inductance (EI) on the current discharge waveforms of HiPIMS at different pulse-on time (Pon) and its relation with static deposition rate and topographical properties of deposited titanium thin films, which is investigated by scanning electron microscope and atomic force microscope. It has shown that the higher the EI, independent of the Pon, the higher the peak power is. The delay time also extensively increases when an EI is implemented into the circuit. However, the rise time does not have a linear dependency with the EI and its behavior changes to some extent at different Pon. By increasing the EI from zero to 30 mH at Pon = 60 μs, the peak power subsequently rises from 11 to 32 kW at constant time-average power. Meanwhile, the deposition rate decreases from 8.5 to 1.5 nm/min, which is mainly attributed to the metal ions return to the target surface and nonlinear dependency of sputtering yield with applied voltage. It was also revealed that the higher peak power has no special effect on the surface roughness of titanium thin films deposited by HiPIMS.

Journal of Theoretical and Applied Physics (JTAP) Memory effect in silicon nitride deposition using ICPCVD technique Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Memory effect in silicon nitride deposition using ICPCVD technique 10.1007/s40094-019-00354-4 EN Sunil Kumar Solid State Physics Laboratory, Delhi, India D. S. Rawal Solid State Physics Laboratory, Delhi, India Hitendra K Malik Plasma Waves and Particle Acceleration Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi, India 0000-0002-9432-8140 Rajeev Sanwal Solid State Physics Laboratory, Delhi, India S. A. Khan Interstate University Accelerator Center, Delhi, India Seema Vinayak Solid State Physics Laboratory, Delhi, India Journal Article 2023 11 17 AbstractIn this study, a plasma-based low-temperature, low-pressure SiN film deposition is investigated for device applications. Ammonia, nitrogen and silane are being used for optimization of the quality of SiN film for device passivation by ICPCVD. Characterization of SiN film is done using elastic recoil detection analysis, AFM, FTIR and ellipsometry. The effect of previous process parameters on subsequent process is called memory effect, which has been investigated by all the characterization techniques. During deposition, this effect has been observed for the same parameters that are used to maintain the stoichiometry of the film. It has been observed that some of the residues of gases used for SiN deposition remain present even after the deposition in the chamber and are carried over for the next deposition process and alter the film property, though parameters such as flow rate, temperature, pressure and time remain fixed. This memory effect alters the film surface roughness and stoichiometry thus affecting device characteristics after passivation.

Journal of Theoretical and Applied Physics (JTAP) Detection of overtone and combined peaks using Mn/Cu helical star-shaped (pine-tree-like) sculptured thin films in surface-enhanced Raman spectroscopy Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Detection of overtone and combined peaks using Mn/Cu helical star-shaped (pine-tree-like) sculptured thin films in surface-enhanced Raman spectroscopy 10.1007/s40094-019-00348-2 EN Reza Babaei Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran Shokoofe Goli‑Haghighi School of Physics, College of Science, University of Tehran, Tehran, Iran Hadi Savaloni School of Physics, College of Science, University of Tehran, North‑Kargar Street, Tehran, Iran 0000-0002-6836-106X Journal Article 2023 11 17 AbstractMn helical star-shaped (pine-tree-like) nano-sculptured thin films with three-, four-and fivefold symmetry on copper substrates were produced using oblique angle deposition method in conjunction with rotation of sample holder at certain angles. Raman spectroscopy of the samples which were subjected to impregnation by 4,4′-bipyridine (C10H8N2) solution was carried out by 632.8 nm wavelength laser. The analysis of the Raman spectra showed enhancement for the 4,4′-bipyridine main bands (1592 and 1297 cm−1) belonging to the C=C stretching mode, aromatic ring stretching ring and in-plane ring mode of 4,4′-bipyridine, same as results obtained for Ag nano-structures. In addition, overtone and combined peaks are detected that may be related to the particular sculptured structure of the thin films fabricated in this work and the laser wavelength used for Raman spectroscopy. UV–Vis (absorption mode) spectra showed consistent observations with the SERS results leading to important role of surface electromagnetic selection rule in intensification of SERS, in addition pointing out the importance of the effect of the size of hot spots on the frequency of the localized surface plasmonic oscillations.

Journal of Theoretical and Applied Physics (JTAP) Investigation of dopant centres dominating the conduction process in the bulk of un-doped GaSb Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Investigation of dopant centres dominating the conduction process in the bulk of un-doped GaSb 10.1007/s40094-019-00355-3 EN Megersa Wodajo Shura Department of Applied Physics, Adama Science and Technology University (ASTU), P. O. Box 1888, Adama, Ethiopia 0000-0001-7800-0789 Journal Article 2023 11 17 AbstractIn this paper, first, the theoretical description of the effects of the dopant densities and the activation energies on the ionization densities, the chemical potentials corresponding to each dopant levels, the majority carrier densities and the Fermi-energy levels in one-acceptor-level system, highly compensated system and two-acceptor-level system are described in detail. Upon fitting the theoretical to the experimental results obtained by the temperature-dependent Hall effect measurements for three samples of un-doped GaSb, the dopant densities and the activation energies for a system with different dopants are investigated. The obtained results revealed that the dopant activation energy has less (no) effect on the Fermi-energy level and the majority carrier density in the highest temperature regimes. The doping density has also less (no) effect on the Fermi-energy level in the lowest temperature regimes. Finally, fitting of the theoretical to the experimental Hall effect measurements results confirmed the presence of three acceptor and one donor levels dominating the majority carrier densities at different temperature regions in all the samples of un-doped GaSb semiconductor.

Journal of Theoretical and Applied Physics (JTAP) Effects of different gas flow rates and non-perpendicular incidence angles of argon cold atmospheric-pressure plasma jet on silver thin film treatment Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Effects of different gas flow rates and non-perpendicular incidence angles of argon cold atmospheric-pressure plasma jet on silver thin film treatment 10.1007/s40094-019-00351-7 EN Maryam Hosseinpour Department of Physics, Faculty of Science, Arak University, P.O. Box: 3848177584, Arak, Iran Akbar Zendehnam Department of Physics, Faculty of Science, Arak University, P.O. Box: 3848177584, Arak, Iran Seyedeh Mehri Hamidi Sangdehi Laser and plasma Research Institute, Shahid Beheshti University (SBU), P.O. Box: 1983969411, Evin, Iran 0000-0002-5298-2224 Hamidreza Ghomi Marzdashti Laser and plasma Research Institute, Shahid Beheshti University (SBU), P.O. Box: 1983969411, Evin, Iran Journal Article 2023 11 17 AbstractIn this study, the influences of variations in the gas flow rate and incidence angles of argon cold atmospheric-pressure plasma jet on the morphology and absorption spectra of silver thin films (60 nm, 80 nm, and 100 nm film thickness) are investigated. To evaluate the surface morphology, atomic force microscopy (AFM) was employed on the silver thin film surface before and after plasma processing. To analyze the effect of plasma treatment on the grain size, the one-dimensional AFM surface profiles of Ag thin films are approximated using a Gaussian function. The absorbance of Ag thin films is measured in wavelength range of 190–1100 nm utilizing UV–Vis absorption spectrometer. Compared to the gas flow rates 0.5 standard litter per minute (SLM) and 2 SLM, surface treatment of Ag thin film with gas flow rate of 1 SLM increased the valley depth, the peak valley height, and the distance between two deepest valleys remarkably. A sequential argon plasma treatment (2-min plasma treatment perpendicular to surface was followed by 2-min plasma processing with non-perpendicular incidence angle of 60°) offers considerable improvement in the uniformity of grains and also changes shape of grains, especially the peak height (about 44 times higher than untreated sample) and area of grains (almost 136 times greater than untreated sample) which can be applicable for optical sensing technology.

Journal of Theoretical and Applied Physics (JTAP) Electrical behavior of graphene under temperature effect and survey of I–T curve Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Electrical behavior of graphene under temperature effect and survey of I–T curve 10.1007/s40094-019-00349-1 EN Maryam Haditale Department of Physics, University of Kurdistan, Sanandaj, Iran R. S. Darian Department of Physics, Alzahra University, Tehran, Iran E. Ghasemian Lemraski Department of Chemistry, Faculty of science, Ilam University, Ilam, Iran Journal Article 2023 11 17 AbstractGraphene flakes were made from electrochemical exfoliation. To study graphene planes, different volumes of graphene solutions (1, 2, 4, and 7 ml) were sprayed on glass lamellae to get different graphene planes. I–V curve of all samples shows ohmic behavior with resistance in the order of kΩ which increases the slope of the I–V curve with increasing graphene planes (spray volume). The effect of temperature on all samples shows a clear jump in I–T curves. It is found that up to 150 °C current is almost constant, but after that current increases highly in the range of 1.8–10 times and resistance reduces sharply. Also, samples with lower graphene planes affected highly with temperature effect.

Journal of Theoretical and Applied Physics (JTAP) Effect of BN nanodots on the electronic properties of α- and β-graphyne sheets: a density functional theory study Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Effect of BN nanodots on the electronic properties of α- and β-graphyne sheets: a density functional theory study 10.1007/s40094-019-00353-5 EN R. Majidi Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran H. Eftekhari Department of Physics, Science and Research Branch, Islamic Azad University, Tehran, Iran H. Bayat Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran Kh. Rahmani Department of Chemistry, Kabul Polytechnic University, Kabul, Afghanistan A. M. Khairogli Department of Chemistry, Faryab University, Maymana, Faryab, Afghanistan Journal Article 2023 11 17 AbstractThe effect of BN nanodots with hexagonal shape on the electronic properties of α- and β-graphyne sheets is investigated. The structural and electronic properties of α- and β-graphyne sheets doped with BN nanodots are studied by using density functional theory. The cohesive energies of the systems indicate all considered structures are thermally stable. It is found that hexagonal BN nanodots can effectively open the band gap in α- and β-graphyne sheets. It means BN nanodots change α- and β-graphyne sheets from semimetal to semiconductor. The BN nanodots with different sizes are considered. It is found that band gaps of the studied α- and β-graphyne sheets doped with BN nanodots increase with the increase in the size of BN nanodots. Hence, α- and β-graphyne sheets doped with BN nanodots are promising materials for use in nanoelectronic devices based on semiconductors.

Journal of Theoretical and Applied Physics (JTAP) Effect of plasma oxidation parameters on physical properties of nanocrystalline nickel oxide thin films grown by two-step method: DC sputtering and plasma oxidation Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Effect of plasma oxidation parameters on physical properties of nanocrystalline nickel oxide thin films grown by two-step method: DC sputtering and plasma oxidation 10.1007/s40094-019-00350-8 EN F. Hajakbari Department of Physics, Karaj Branch, Islamic Azad University, Karaj, Iran S. Rashvand Department of Physics, Karaj Branch, Islamic Azad University, Karaj, Iran A. Hojabri Department of Physics, Karaj Branch, Islamic Azad University, Karaj, Iran Journal Article 2023 11 17 AbstractNanocrystalline nickel oxide (NiO) thin films were successfully grown on quartz substrates by two-step method. In the first step, nickel films were deposited on quartz substrates by DC magnetron sputtering technique. Then, the plasma oxidation of nickel films was used for preparation of nickel oxide. The effect of DC plasma power and treatment time on the structural, morphological and optical properties of the NiO films were investigated by different analyses. XRD results indicated that the plasma powers effectively influenced the structure of films, and the best crystallinity was obtained for plasma power of 15 w and treatment time of 20 min. The XPS, RBS and EDS analysis confirmed the presence of Ni and O elements. The FESEM and AFM images showed a granular structure with spherical shapes of grains. The optical band gap of the films synthesized under different plasma oxidation conditions was also discussed.

Journal of Theoretical and Applied Physics (JTAP) Density functional theory study on the effect of Cu- and Na-substituted layers on spin-dependent transport and TMR in the Fe/ZnO/Fe MTJ Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Density functional theory study on the effect of Cu- and Na-substituted layers on spin-dependent transport and TMR in the Fe/ZnO/Fe MTJ 10.1007/s40094-019-00346-4 EN Masoud Ansarino Department of Physics, South Tehran Branch, Islamic Azad University, Tehran, Iran 0000-0002-2311-5068 Journal Article 2023 11 17 AbstractUsing density functional theory, effects of Na- and Cu-substituted layers on the spin-dependent electronic transport properties of Fe/ZnO/Fe magnetic tunnel junction based on zinc oxide barrier tunnel, with rock-salt crystalline structure, have been studied. In zero-bias voltage, conductance and tunneling magneto-resistance (TMR) ratio of structures are calculated. It is showed that substituted layers in the pristine junction greatly affect conductance and TMR ratio of this junction. The results indicated that Cu-substituted layer with reducing conductance of pristine structure in the antiparallel alignment configuration, and increasing its conductance in the parallel alignment, leads to a large TMR ratio, up to 1800%. Due to the large conductance of pristine and Cu-substituted devices in the parallel alignment, these structures would be very beneficial for experimental applications that require the spin-polarized current.

Journal of Theoretical and Applied Physics (JTAP) Photon decaying in de Sitter universe Volume 13, 2019 Issue 4, November and December 2019 2023 11 17 Photon decaying in de Sitter universe 10.1007/s40094-019-00356-2 EN Y. Ahmadi Department of Physics, Razi University, Kermanshah, Iran M. V. Takook Department of Physics, Kharazmi University, Tehran, Iran 0000-0003-4038-3176 Journal Article 2023 11 17 AbstractThe interaction between three photons is studied in de Sitter ambient space formalism. As a special case, the half harmonic generator is considered, i.e., one photon decays to two same-energy photons. The scattering matrix elements are presented which define the indirect gravitational effect on quantum field theory. The null curvature limit of scattering matrix is obtained for comparing it with its Minkowskian counterpart. The Hamiltonian of this interaction, in Minkowski space–time, was presented by using the quantum vacuum fluctuation in the one-loop approximation.