A novel collimated glancing angle deposition (GLAD) modality in conjunction with e-beam evaporation technique has been explored to engineer Ag nano-morphology for achieving enhanced birefringence. The nano-columner Ag thin films exhibiting strong optical birefringence have been fabricated by both conventional GLAD and novel collimated GLAD techniques. Simultaneous optical analysis of the samples using polarized transmittance spectra and spectroscopic ellipsometry spectra reveal that conventional GLAD films are more suitable for tunable optical polarizer application while collimated GLAD Ag thin films have an edge over conventional GLAD for waveplate/retardation plate application. The easy to fabricate negative uniaxial Ag nanostructures may serve as an important building block towards replacement of bulky birefringent material based optics with miniaturized thin film based optics.

High-quality MoS2 2 nanostructures were fabricated via chemical vapor deposition technique on SiO2/Si 2 /Si substrate. In this paper, the effect of temperature on the photoluminescence behavior of MoS2 2 dendritic flake is addressed. We scrutinized the photoluminescence spectra of monolayer and multilayer regions of MoS2 2 in the temperature range 300 K-680 K. Monolayer and multilayer behavior of MoS2 2 flakes are confirmed by Raman and Photoluminescence spectroscopy. The excitonic peaks from the multilayer regime become less intense and show a red shift compared to the monolayer PL spectra. Thermally-induced bandgap modulation of MoS2 2 is demonstrated. The excitonic intensity and peak positions reveal pronounced temperature-dependent changes. These changes are explicable through the increased electron-phonon interaction and lattice rearrangements. Furthermore, first principle calculations are employed to glean insight into the impact of atomic rearrangements on the band gap behavior of MoS2. 2 . Our research presents a detailed understanding of thermally driven band gap modulation of monolayer and multilayer MoS2, 2 , which is essential for designing optoelectronic devices.

We report nanosecond laser texturing of crystalline silicon with subsequent superhydrophilic and heat resistive properties. The samples are laser processed in ambient conditions in normal atmospheric pressure. Micro structures with micro/nano channels are evolved after processing which contributes to the wettability change of the silicon surface. The samples are characterized by XRD, FESEM, EDX and Raman spectroscopy. The contact angles are measured using an indigenously built contact angle goniometer. The samples show superhydrophilic nature after laser processing. Interestingly, the samples retain their inherent properties and super-wettability even after annealing at 200 degrees C for 8 hours. Such architectures could find applications in devices working in high temperature environments.

In all-solid-state thin-film batteries, the interface properties between solid electrolytes and solid electrodes are the major factors limiting their performances; however, knowledge of the interface properties is limited in most of the cases. Using the magnetron sputtering technique, thin films of Li3+xPO4-xNx (LiPON) solid-state electrolyte along with LiPON/TiO2 (anode) and LiPON/LiNi0.33Mn0.33Co0.33O2 (LNMC) (cathode) thin-film bilayers have been prepared under different sputtering conditions and characterized by spectroscopic ellipsometry to study the properties of electrolyte/anode and electrolyte/cathode interfaces of Li-ion solid-state batteries. Spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry studies of single-layer LiPON showed that radiofrequency (RF) power and nitrogen pressure used during deposition control the nitrogen and lithium contents of the film. Films deposited at a higher RF power showed a lower refractive index, which signifies a lower nitrogen content and a more Li3PO4-like film; impedance measurements also confirmed this result. The interface width found from the ellipsometric study of the LiPON/TiO2 and LiPON/LNMC bilayer films showed that the nitrogen content of the LiPON layer has a very strong effect on the interface as well as on the lithiation of the TiO2 layer during LiPON sputtering; higher nitrogen content in the LiPON layer increases both. This finding has also been supported by cross-sectional FESEM results. Hybrid half-cells of the TiO2 anode and LNMC cathodes have been prepared using a higher nitrogen content LiPON electrolyte. The stable electrochemical performance of the cells manifests that higher interface width favors the formation of a stable solid electrolyte interface layer at the anode-electrolyte interface.

Devices with controllable conversion of analog to digital resistive switching are essential for next-generation memory and sensing technologies, where precise modulation of defect dynamics enables reliable and tunable performance. This work reports the influence of Cu ions on the transition from analog to digital resistive switching in Indium–Tin-Oxide(ITO)/NiO/Ag memristor devices. The undoped and low-concentration Cu doping illustrates the analog switching, whereas higher doping demonstrates the digital characteristics. At higher bias voltage, the Schottky barrier ( ϕ B ) is developed at both ITO/NiO and NiO/Ag interfaces. The increasing and decreasing of current conduction with the escalating number of cycles for both the polarity in undoped and low doped is elucidated by the electrode-dominated mechanism in terms of reduction and enhancement of Schottky barrier height at the interface, respectively. The digital switching characteristic due to the formation and rupturing of the vacancy filament in the highest fluence sample (2 × 10 16 ions cm −2 ) is induced due to the boosting of vacancies externally above the critical amount using ion implantation. The synergic effect of the increase and decrease of the current conduction in the analog resistive switching device can be utilized as a learning and forgetting process for neuromorphic applications.

Advancements in 2D magnetic materials highlight their potential in semiconductors, magnetism, and spintronics, particularly in tuning magnetic properties for spintronic applications. This study investigates the impact of low-energy (30 KeV) Au ion implantation on 2D layered exfoliated Cr_2Ge_2Te_6 flakes prepared on Si/SiO_2 substrates using the Scotch tape method. Five different ion doses (5×10^13, 1×10^14, 5×10^14, 1×10^15, and 2.5×10^15 ions/cm^2) were used to modify the morphology, composition, structural, and vibrational properties of the samples. The implantation introduces significant changes in morphology and magnetic behavior, leading to an increase in Curie temperature and an attribution from superexchange to double exchange interactions. The reduced exchange energy gaps and modified magnetic moments attribute to Au ions intercalation in Cr_2Ge_2Te_6 underscore the potential of ions implantation to tune the magnetic properties of 2D materials for advanced spintronic applications.

Developing a stable, solar-absorbing layer with earth-abundant elements is key for next-gen photovoltaics. A Mott insulator (MI) transition metal oxide like LaMnO3 (LMO) offers affordability and stability, making it promising for solar cells. This study explores a comprehensive experimental and theoretical investigation into its photovoltaic efficiency using the pulse laser deposition (PLD) technique and SCAPS-1D simulation tool. We employed the Nb: SrTiO3 (NSTO) substrate and Cu2O as the electron transport and hole transport layers, respectively. A detailed structural characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy studies confirms the highly crystalline c-axis oriented growth of the LMO perovskite phase. Characterization of the optical properties via diffuse reflectance spectroscopy (DRS) identifies a direct band gap of 1.15 eV for LMO, while the photoluminescence (PL) measurements reveal an emission peak at 460 nm, indicating no relaxation processes. The first-principle calculations suggest that the system possesses similar electronic and optical band gaps, which closely align with the experimental results observed in the Tauc plot. Additionally, we have conducted a simulation study of the solar cell with a planner architecture as Nb:STO/LMO/Cu2O and compared it with the experimental results from a PLD-grown LMO solar cell. The simulation results predict a power conversion efficiency (PCE) of 6.2%, while the experimentally grown solar cell achieves a PCE of 0.9%, which may be due to the limited charge transport kinetics. More importantly, inserting a correlated metallic SrRuO3 (SRO) buffer layer in the device offers a significant enhancement of the PCE (similar to 38%) from 0.9 to 1.25%, highlighting better electron transport (J sc increased by 118%). Impedance measurements on the optimized Nb:STO/SRO/LMO/Cu2O/Au device revealed a series resistance of 52.6 Omega and junction capacitance of 96.8 pF. Our complementary experimental and theoretical findings on these solar cells signify a pivotal advancement toward realizing MI solar cells beyond conventional semiconductors.

High-quality MoS2 nanostructures were fabricated via chemical vapor deposition technique on SiO2/Si substrate. In this paper, the effect of temperature on the photoluminescence behavior of MoS2 dendritic flake is addressed. We scrutinized the photoluminescence spectra of monolayer and multilayer regions of MoS2 in the temperature range 300 K–680 K. Monolayer and multilayer behavior of MoS2 flakes are confirmed by Raman and Photoluminescence spectroscopy. The excitonic peaks from the multilayer regime become less intense and show a red shift compared to the monolayer PL spectra. Thermally-induced bandgap modulation of MoS2 is demonstrated. The excitonic intensity and peak positions reveal pronounced temperature-dependent changes. These changes are explicable through the increased electron–phonon interaction and lattice rearrangements. Furthermore, first principle calculations are employed to glean insight into the impact of atomic rearrangements on the band gap behavior of MoS2. Our research presents a detailed understanding of thermally driven band gap modulation of monolayer and multilayer MoS2, which is essential for designing optoelectronic devices.

Spin-phonon interaction plays an important role in 2D magnetic materials and motivates the development of next-generation spin- and charge-dependent microelectronic devices. Understanding the spin-phonon interaction by tuning the growth parameter of single crystal Cr$_2Te_3$, a robust quasi-2D room temperature magnetic material, is crucial for spintronic devices. The synthesis of single crystal 2D Cr$_2Te_3$ flakes on a Si substrate from co-deposited thin film by plasma annealing techniques is a significant achievement. The temperature dependence and polarization-resolved Raman spectroscopy with support of density functional theory classified lattice symmetry operations were used to identify the phonon modes to investigate the spin/electron-phonon interactions in Cr$_2Te_3$. The mean-field theory model in single crystal Cr$_2Te_3$ is employed to quantify the spin-phonon interaction and correlate with in-plane and out-of-plane magnetic behavior. The observation of a positive correlation between phonon mode frequency and spin-phonon interaction strength in single crystal Cr$_2Te_3$ can be a potential candidate for spintronic applications.

In thin film multilayer based optical componentsof x-ray imaging system, diffusion of one material into the other degrades the reflectivity of the mirrors severely. Along with this thermodynamically driven diffusion, there are also growth generated interface roughness of different special frequencies and microstructures which can increase the diffused scattering from the multilayer and reduce the resolution of an image. Generally grazing incidence x-ray reflectivity in specular geometry (specular GIXR) and diffused x-ray scattering measurement in rocking scan geometry yield information regarding microstructure and overall diffusion at the interfaces of a multilayer. In this paper it is shown that grazing incidence x-ray fluorescence (GIXRF) measurement in standing wave condition alongwith the above measurements can give precise information regarding element-specific diffusion at the interfaces of a multilayer structure. Periodic multilayers made of 75 Cr/Sc bilayers with bilayer thickness similar to 4 nm with and without B4C barrier layer of 0.2 nm thickness at the interfaces have been prepared using ion beam sputtering system and characterized by GIXR, diffused x-ray scattering and GIXRF measurements using synchrotron x-ray radiation just above the Cr K-edge. From the above measurements, drastic reduction in interface diffusion of Cr and improvement of interface morphology after addition of B4C barrier layer at the interfaces of Cr/Sc multilayers have been observed which is also corroborated by cross-sectional transmission electron microscopy of the multilayers. Finally, in the water window soft x-ray region of 2.3-4.4 nm performance of these multilayers have been tested and the Cr/B4C/Sc multilayer with improved interface quality has been found to yield similar to 30.8% reflectivity at 3.11 nm wavelength which is comparable with the best reported reflectivities in the literature at this wavelength.

ZnSnS3, a newly theoretically predicted ferroelectric material which shows promising properties for solar cell and photovoltaic applications, was successfully grown in our laboratory by hydrothermal method. The high intensity x-ray diffraction pattern from the (211), (10(1) over bar), (200), (210), (310), (320), and (32(1) over bar) planes reveal the crystalline character of the trigonal ZnSnS3 phase. The microstructural property and elemental distribution were evaluated using SEM and TEM studies. Diffuse reflectance measurement at room temperature shows a direct bandgap of 2.62 eV along with a high energy direct transition of 3.13 eV. Two broad photoluminescence peaks at various temperatures (4-300 K) were also detected around (2.61-2.73 eV) and (3.04-3.11 eV). The emission characteristics are explained considering the shallow donor level to valence band transitions. Raman study elucidates that the synthesized ZnSnS3 possess a good number of Raman active bands. A phase transition from the ferroelectric to non-ferroelectric phase of ZnSnS3 is observed around 330 degrees C in DSC and dielectric measurements. The P-E measurement showed that the material is ferroelectric in nature with saturation polarization value of 21.85 mu C/cm(2). The current-voltage characteristics showgood photovoltaic response of the fabricated Ni/ZnSnS3/Ni device in the visible range indicating its application in PV devices and photodetector.

Local fluctuations in the superconducting order parameters in granular systems show interesting magnetotransport behavior, particularly relevant to superconducting nanowires. Kivelson and Spivak [Phys. Rev. B 45, 10490 (1992)] have shown that fluctuations in density and signs of supercurrent can lead to oscillating and negative magnetoresistance (MR). Here, we present magnetoresistance measurements of 100 nm wide NiBi3 superconducting nanowires, patterned by focused ion beam lithography, from granular NiBi3 films containing different concentrations of magnetic Ni impurities. The nanowire containing a higher concentration of Ni impurity showed oscillations in MR and simultaneously exhibited negative MR in certain temperature and field ranges. None of these effects were observed in the nanowire with nearly no Ni impurities. Unlike earlier experiments, we argue that excess magnetic Ni impurities in the nanowire realize a case of simultaneous magnitude and sign fluctuations in local order parameter, leading to MR oscillations and MR sign reversal in the same system, as discussed by Kivelson and Spivak. This result is important in the context of transport in superconducting quantum circuits.

Understanding the interaction of various environmental oxidizing agents is important in determining the physical and chemical properties of 2D materials. Its impact holds great significance for the practical application of these materials in nanoscale devices functioning under ambient conditions. This study delves into the influence of O 2 and O 3 exposure on the structural and electronic characteristics of the C 2 N monolayer, focusing on the kinetics of adsorption and dissociation reactions. Employing first‐principles density‐functional theory calculations alongside climbing image nudged elastic band calculations, it is observed that the monolayer exhibits resistance to ozonation, evidenced by energy barriers of 0.56 eV. These processes are accompanied by the formation of COC groups. Furthermore, the dissociation mechanism involves charge transfers from the monolayer to the molecules. Notably, the dissociated configurations demonstrate higher bandgaps compared to the pristine monolayer, attributed to robust CO hybridization. These findings suggest the robustness of C 2 N monolayers against oxygen/ozone exposures, ensuring stability for devices incorporating these materials.

The combination of 2D materials and noble metallic nanostructure is becoming an attractive research domain for label-free, highly sensitive surface-enhanced Raman spectroscopy (SERS) applications. This study demonstrated photocatalysis degradation and SERS enhancements of organic fluorophore (Rhodamine 6G) on two-dimensional (2D) TiSe 2 using Raman spectroscopy. The Au nanoparticles (NPs) were decorated on TiSe 2 thin films by thermal annealing at variable temperatures. The selective deposition of Au NPs on the hexagonal TiSe 2 nanocrystals increases surface roughness, creating a larger surface area for molecule adsorption. It has been observed that the Au decoration at 250 °C on TiSe 2 exhibits efficient detection capabilities for R6G with the Raman intensity enhancement factors of the order of ≈10 5 along with the significantly improved visible light-induced photodegradation efficiency. The optimized Au NP size creates large electromagnetic hot spots produced by strong plasmon coupling that assists in the charge transfer mechanism among TiSe 2 , Au NPs, and R6G for enhanced SERS and photocatalysis activities. It has been observed that the intensity of Raman scattering decreases as the Au NP size increases on the TiSe 2 material. A possible charge transfer mechanism is proposed with an energy band diagram. The simultaneous measurement of SERS and photocatalytic dye degradation in Au decorated TiSe 2 can be used as a sensitive technique for water pollution treatment and biodegradable organic contaminants for the environmental ecosystem.

The development of renewable energy technologies is critical to addressing global challenges, such as climate change and ensuring energy sustainability. One promising approach is photocatalytic water splitting, which converts solar energy into hydrogen fuel. 2D materials, especially van der Waals heterostructures, have shown great potential for enhancing photocatalytic activity. In this study, we investigated the effects of vertical, uniaxial, and biaxial strain on the electronic band gap and band edge positions of the C2N/MoS2 van der Waals heterostructure through first-principles density functional theory using both Perdew-Burke-Ernzerhof (PBE) parameterization-based generalized gradient approximation (GGA) and strongly constrained and appropriately normed (SCAN) meta-GGA functional. Our results indicated that the SCAN functional provided more accurate results for band gap and band alignment, which are close to the experimental values as compared to the PBE functional. We discovered that the heterostructure exhibited a type-II band alignment, which is essential for efficient charge separation. Our calculation also established that the band edge positions straddled the water redox potential under compressive strain, suggesting its usefulness as an efficient photocatalyst to execute hydrogen/oxygen evolution reactions, whereas, for tensile uniaxial and biaxial strains, the band alignment is within the water oxidation/reduction potential. Furthermore, our study established that the meta-GGA SCAN functional yielded results similar to those of computationally expensive hybrid HSE functionals, reducing the computational cost of electronic structure calculations. Our findings provide valuable insights for designing 2D heterostructure devices with improved photocatalytic water-splitting performance.

The process of environmental oxidation is pivotal in determining the physical and chemical properties of two-dimensional (2D) materials. Its impact holds great significance for the practical application of these materials in nanoscale devices functioning under ambient conditions. This study delves into the influence of O2 and O3 exposure on the structural and electronic characteristics of the C2N monolayer, focusing on the kinetics of adsorption and dissociation reactions. Employing first-principles density functional theory calculations alongside climbing image nudged elastic band calculations, we observe that the C2N monolayer exhibits resistance to oxidation and ozonation, evidenced by energy barriers of 0.05 eV and 0.56 eV, respectively. These processes are accompanied by the formation of epoxide (C-O-C) groups. Furthermore, the dissociation mechanism involves charge transfers from the monolayer to the molecules. Notably, the dissociated configurations demonstrate higher bandgaps compared to the pristine C2N monolayer, attributed to robust C-O hybridization. These findings suggest the robustness of C2N monolayers against oxygen/ozone exposures, ensuring stability for devices incorporating these materials.

By surpassing single perovskites, double perovskites without any sort of Lead content are applicable as materials for solar and related applications due to their more stable nature, good catalytic efficiency, and negligible toxicity. So as to investigate the structural, electrical, and other diverse aspects of the Bi 2 FeCrO 6 and Bi 1.8 La 0.2 FeCrO 6 materials, we have synthesised them using a traditional solid-state reaction technique. By performing X-ray diffraction study, the crystal structures for both the samples are found to be monoclinic. The sample’s strain and crystallite sizes were extracted using the Williamson-Hall formalism. Molecular bonding and metal oxide vibrations like Bi–O and Fe–O were analysed via Fourier transform infrared (FTIR) spectroscopy. To further verify crystal structure and optical phonon modes, Raman spectroscopy has been performed. The surface analysis of the samples recorded by FESEM reveals that the small grains are allocated homogeneously through distinctive grain barrier. Diffuse reflectance spectroscopy revealed narrow band gaps for both samples which makes them suitable for photo-catalytic actions. The extracted valence band maximum (VBM) levels of the samples are in the domain of O 2 evolution criteria. Along with the Urbach energy, refractive indices were also calculated in optical studies. For electrical study, dielectric characteristics of the compounds were analysed over a large temperature series. The thermal variation of the frequency exponent (n) obtained from the fitting of Jonscher’s rule verified the existence of the correlated barrier hopping conduction method. From impedance spectroscopy, negative temperature coefficients of resistance (NTCR) response in addition to non-Debye type of relaxation were noted. DC conductivity experiments provide the activation energy of the materials. Thermistor applicability for samples shows promising results. Ferroelectricity has been confirmed for both the samples.

In this work, we report magnetic and optical anisotropies in tilted nickel (Ni) nanocolumns and their dependencies on the film growth conditions. The Ni nanocolumns were prepared using electron beam evaporation technique in conjunction with glancing angle deposition methodology. The film depositions were performed at various in-situ substrate temperatures viz. 30 °C, 150 °C, 250 °C and 300 °C. An increase in material density with in-situ substrate temperature due to the thermal diffusion mediated coalescence of neighbouring grains was observed. The results were further corroborated with the alterations in surface morphology of the films. The modification in tilt angle of the Ni nanocolumns was also observed with in-situ substrate heating due to the non-ballistic growth approach. The presence of uniaxial optical anisotropy was established in the films deposited at low substrate temperatures (< 250 °C) using generalized ellipsometry (GE). However, the uniaxial optical anisotropy was found to be negligible for the high temperature deposited films due to thermal diffusion effect. SQUID measurements were performed for quantification of magnetic anisotropy in the films. The estimated magnetic anisotropy energy confirmed low substrate temperature deposited films to be more anisotropic as compared to others. Magnetic coercivity of the films showed film porosity dependent changes in the field values. Overall, the present investigation demonstrates anisotropic behaviour of nanocolumnar nickel thin films for non-ballistic glancing angle deposition.