In this work, we present the investigation of resistive switching properties in Ag/SiOx/Cr RRAM devices. We fabricate the devices and analyze the effect of compliance current on the device behavior. Electrical characterization reveals the bipolar and threshold switching depending on the value of compliance current. We use electrochemical impedance spectroscopy to obtain information about the forming process, exposing metal ions migration during the process.

This study investigates the influence of the top metal electrode on the resistive switching (RS) behavior of the metal/TiOx/ITO structure. Specifically, the effects of Al and TiN as top electrodes were examined in devices utilizing a 30 nm TiOx thin film as the active layer, deposited using a pulsed-DC reactive sputtering technique. Both configurations exhibited non-volatile bipolar resistive switching, demonstrating endurance over 100 cycles and stable data retention (>10(4) s). The results indicate that the choice of top electrode (TE) plays a crucial role in determining the electroforming process, current conduction mechanisms, and overall RS performance. Notably, devices with TiN as a TE exhibited more consistent RS behavior, with a superior ON/OFF ratio and enhanced operational stability. These findings demonstrate that electrode engineering offers a viable pathway to enhance resistive switching performance. The insights gained from this study provide a basis for the rational design and optimization of CMOS-compatible TiOx-based resistive random-access memory (RRAM) devices.

In this work, the temperature effect in dielectric, impedance, and leakage current characteristics of TiOxincorporated HfOx (HTO) thin film integrated into metal-oxide-semiconductor (MOS) structure were investigated. The thin HTO layer was prepared using a pulsed-DC reactive magnetron sputtering technique. The successful preparation of HTO has been confirmed by analyzing the spectral profile of the refractive index. Energy dispersive X-ray analysis was employed to determine the elemental composition of the oxide film. The capacitance-frequency study of the Al/HTO/p-Si structure was carried out over a temperature range of 25 to 100 degrees C and a frequency range of 1 kHz to 3.5 MHz. The experimental results indicate that the dielectric constant, dielectric loss, and AC conductivity increase with rising temperature. Detailed impedance spectroscopy analysis reveals that the composite film follows a non-Debye type relaxation process signifying thermally activated dielectric relaxation and a reduced relaxation time with increasing temperature. The current-voltage characteristics demonstrated that the leakage current of the device increases with temperature, while exhibiting a nominal value within the measured temperature range. The findings underscore the influence of temperature on the dielectric, impedance, and leakage current properties of HTO films, providing key insights into enhancing the reliability of Al/HTO/p-Si MOS devices, particularly under high-temperature operation.

Memristors with resistive switching capabilities are vital for information storage and brain-inspired computing, making them a key focus in current research. This study demonstrates non-volatile analog resistive switching behavior in Al/TiOx/TiN/Si(n++)/Al memristive devices. Analog resistive switching offers gradual, controllable conductance changes, which are essential for mimicking brain-like synaptic behavior, unlike digital/abrupt switching. The amorphous titanium oxide (TiOx) active layer was deposited using the pulsed-DC reactive magnetron sputtering technique. The impact of increasing the oxide thickness on the electrical performance of the memristors was investigated. Electrical characterizations revealed stable, forming-free analog resistive switching, achieving endurance beyond 300 DC cycles. The charge conduction mechanisms underlying the current–voltage (I–V) characteristics are analyzed in detail, revealing the presence of ohmic behavior, Schottky emission, and space-charge-limited conduction (SCLC). Experimental results indicate that increasing the TiOx film thickness from 31 to 44 nm leads to a notable change in the current conduction mechanism. The results confirm that the memristors have good stability (>1500 s) and are capable of exhibiting excellent long-term potentiation (LTP) and long-term depression (LTD) properties. The analog switching driven by oxygen vacancy-induced barrier modulation in the TiOx/TiN interface is explained in detail, supported by a proposed model. The remarkable switching characteristics exhibited by the TiOx-based memristive devices make them highly suitable for artificial synapse applications in neuromorphic computing systems.

Understanding the resistive switching (RS) mechanisms in memristive devices is crucial for developing non-volatile memory technologies. Here, we investigate the memristor effect in hydrothermally grown Au-nanoseeded CuO films. Based on I-V measurements, conductive-AFM, S/TEM, and EDS analyses, we examine the changes within the switching layer associated with RS. Our results reveal a filamentary mechanism of RS. Notably, EDS mapping shows directional Au redistribution between the bottom nanoseeds and the top electrode, while Cu and O remain uniformly distributed. These findings support an electrochemical metallization (ECM)-like filamentary mechanism driven by Au species migration. The use of Au-nanoseeds, required by the solution-based growth method, critically affects filament formation and RS behavior. Our results emphasize the importance of microstructure and electrode-oxide interfaces in determining the switching mechanism in oxide-based memristors.

Resistive switching (RS) phenomena are nowadays one of the most studied topics in the area of microelectronics. It can be observed in Metal–Insulator–Metal (MIM) structures that are the basis of resistive switching random-access memories (RRAMs). In the case of commercial use of RRAMs, it is beneficial that the applied materials would have to be compatible with Complementary Metal-Oxide-Semiconductor (CMOS) technology. Fabricating methods of these materials can determine their stoichiometry and structural composition, which can have a detrimental impact on the electrical performance of manufactured devices. In this study, we present the influence of the Ar/N2 ratio during reactive magnetron sputtering of titanium nitride (TiN) electrodes on the resistive switching behavior of MIM devices. We used silicon oxide (SiOx) as a dielectric layer, which was characterized by the same properties in all fabricated MIM structures. The composition of TiN thin layers was controlled by tuning the Ar/N2 ratio during the deposition process. The fabricated conductive materials were characterized in terms of chemical and structural properties employing X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis. Structural characterization revealed that increasing the Ar content during the reactive sputtering process affects the crystallite size of the deposited TiN layer. The resulting crystallite sizes ranged from 8 Å to 757.4 Å. The I-V measurements of fabricated devices revealed that tuning the Ar/N2 ratio during the deposition of TiN electrodes affects the RS behavior. Our work shows the importance of controlling the stoichiometry and structural parameters of electrodes on resistive switching phenomena.

This study investigates the frequency-dependent dielectric properties of ultrathin HfOx-TiOx composite films (HTO) in a metal-oxide-semiconductor (MOS) configuration over a frequency range of 1 kHz to 3 MHz. The films were deposited using a pulsed-DC magnetron sputtering technique in an atomic layer deposition-like manner, incorporating very thin TiOx layers within the bulk of HfOx. Structural analysis revealed that the films are amorphous and exhibit uniform and smooth surfaces. The dielectric constant (epsilon ') and dielectric loss (epsilon '') exhibit a decreasing trend with increasing frequency, demonstrating typical dielectric behavior. Furthermore, the characteristic dielectric relaxation frequency shifts toward lower frequency values with the insertion of TiOx. The Cole-Cole plot confirms the non-Debye relaxation behavior across all samples. Optical spectroscopy analysis reveals a systematic increase in the optical band gap upon more TiOx insertion. Analysis of current-voltage (I-V) characteristics demonstrates low leakage currents across the composite films. Understanding the dielectric parameters and the electrical characteristics is crucial for the potential application of these films in advanced electronic applications.

This paper is devoted to the technology and characterization of thin films fabricated by reactive magnetron sputtering using HIPIMS discharge. The metal oxides and nitrides, such as zirconium oxide (ZrOx), titanium oxide (TiOx) or titanium nitride (TiN) play important functions in various structures for novel electronic and photonic devices. This work aims to determine dependencies between the input parameters of the fabrication process and the properties of the obtained materials to obtain ultrathin layers for the application of the MIM (Metal-Insulator-Metal) structures. Those structures are the basis of resistive random-access memory (RRAM) devices. In the first part of this work, the optical properties of layers deposited by HIPIMS were compared to those deposited using a typical pulsed-DC process. In the UV-VIS range, several oxide materials were characterized in terms of thickness, refractive indices, transmittance, and reflectance. The resistive switching properties of the MIM structures with the employed oxide materials depend on the presence of oxygen vacancies in the layer bulk. In order to monitor the stoichiometry of the oxide layers, MIS (Metal-Insulator-Semiconductor) structures are fabricated. The analysis of the obtained electrical characteristics was performed. In the last part of this work, selected processes were used to fabricate MIM devices. The results of the electrical characterization of the fabricated test structures will be described indicating concluding remarks on the feasibility of applying the studied structures in RRAM devices.

This work demonstrated the optimization of HiPIMS reactive magnetron sputtering of hafnium oxynitride (HfOxNy) thin films. During the optimization procedure, employing Taguchi orthogonal tables, the parameters of examined dielectric films were explored, utilizing optical methods (spectroscopic ellipsometry and refractometry), electrical characterization (C-V, I-V measurements of MOS structures), and structural investigation (AFM, XRD, XPS). The thermal stability of fabricated HfOxNy layers, up to 800 °C, was also investigated. The presented results demonstrated the correctness of the optimization methodology. The results also demonstrated the significant stability of hafnia-based layers at up to 800 °C. No electrical parameters or surface morphology deteriorations were demonstrated. The structural analysis revealed comparable electrical properties and significantly greater immunity to high-temperature treatment in HfOxNy layers formed using HiPIMS, as compared to those formed using the standard pulsed magnetron sputtering technique. The results presented in this study confirmed that the investigated hafnium oxynitride films, fabricated through the HiPIMS process, could potentially be used as a thermally-stable gate dielectric in self-aligned MOS structures and devices.

In this paper differences in chemical composition of ultra-thin silicon oxynitride layers fabricated in planar rf plasma reactor are studied. The ultra-thin dielectric layers were obtained in the same reactor by two different methods: ultrashallow nitrogen implantation followed by plasma oxidation and plasma enhanced chemical vapour deposition (PECVD). Chemical composition of silicon oxynitride layers was investigated by means of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The spectroscopic ellipsometry was used to determine both the thickness and refractive index of the obtained layers. The XPS measurements show considerable differences between the composition of the fabricated layers using each of the above mentioned methods. The SIMS analysis confirms XPS results and indicates differences in nitrogen distribution.

This work reports on changes in the properties of ultra-thin PECVD silicon oxynitride layers after high- temperature treatment. Possible changes in the structure, composition and electrophysical properties were investigated by means of spectroscopic ellipsometry, XPS, SIMS and electrical characterization methods (C-V, I-V and charge- pumping). The XPS measurements show that SiOxNy is the dominant phase in the ultra-thin layer and high-temperature annealing results in further increase of the oxynitride phase up to 70% of the whole layer. Despite comparable thickness, SIMS measurement indicates a densification of the annealed layer, because sputtering time is increased. It suggests complex changes of physical and chemical properties of the investigated layers taking place during high-temperature annealing. The C-V curves of annealed layers exhibit less frequency dispersion, their leakage and charge-pumping currents are lower when compared to those of as-deposited layers, proving improvement in the gate structure trapping properties due to the annealing process.

This work presents the preliminary research on Metal-Insulator-Metal (MIM) structures containing copper oxide (CuO) layers for memory applications. Structural and optical investigations of fabricated materials have shown distinct differences in chemical compositions of 'as grown' and thermally annealed CuO, i.e., 'HT + RTP' film. Those differences strongly influence the electrical behavior of fabricated MIM structures. The examined electrical performance of fabricated devices revealed stability and repeatability of the HRS/LRS ratio over time. The presented results have demonstrated the possible application of CuO thin films in low-power and high-speed Resistive Random-Access Memory (RRAM) devices.

Gallium nitride (GaN) doped with germanium at a level of 1020 cm−3 is proposed as a viable material for cladding layers in blue- and green-emitting laser diodes. Spectral reflectometry and ellipsometry are used to provide evidence of a reduced index of refraction in such layers. The refractive-index contrast to undoped GaN is about 0.990, which is comparable to undoped aluminium gallium nitride (AlGaN) with an aluminium composition of 6%. Germanium-doped GaN layers are lattice-matched to native GaN substrates; therefore, they introduce no strain, cracks, and wafer bowing. Their use, in place of strained AlGaN layers, will enable significant improvements to the production process yield.

This study presents the results of the optimization of the optical properties of TiN and TiOx thin films by employing Taguchi orthogonal tables approach. The presented results demonstrated the possibility to tune the optical properties of investigated conductive/dielectric films in the UV-Vis range by the appropriate setting of sputtering parameters. The presented findings are the basis for the fabrication of periodic stacks for the application in the technology of metamaterials.

In this study, an analysis of the second-harmonic generation (SHG) response from surfaces containing dielectric-semiconductor interfaces with sub-wavelength features is presented. The investigated medium is a metamaterial where the SHG response is governed by the symmetry breaking between consecutive layers. The examined material is composed of a periodic structure based on 50 nm silicon nitride and 10 nm indium gallium zinc oxide (IGZO) fabricated on a quartz glass substrate. The elementary cell consists of a pair of materials in an exchangeable order. The preliminary results show a promising application of the amorphous IGZO as a nonlinear optical material, whose optical characteristics can be controlled by the fabrication process itself. Prepared structures give a remarkably high SHG response. For an effective thickness of the structure equal to 240 nm, a more than 250-fold increase in SHG compared to the reference substrate is observed.

Colloidal cubic SiC-NCs have been introduced into MIM structures with HfO<inf>x</inf> layers. The examined electrical performance of NCs-MIM structures has demonstrated improved switching characteristics, good retention, and a high HRS/LRS ratio compared to reference structures. The presented results have shown the feasibility of applying SiC-NCs in RRAM devices.

The continuous development of ALD thin films demands ongoing improvements and changes toward fabricating materials with tailored properties that are suitable for different practical applications. Ozone has been recently established as a precursor, with distinct advantages over the alternative oxidizing precursors in the ALDs of advanced dielectric films. This study reports alumina (Al2O3) and hafnia (HfO2) formation using an O3 source and compares the obtained structural and electrical properties. The performed structural examinations of ozone-based materials proved homogenous high-k films with less vacancy levels compared to water-based films. The enhanced structural properties also result in the problematic incorporation of different dopants through the bulk layer. Furthermore, analysis of electrical characteristics of the MIS structures with ALD gate dielectrics demonstrated the improved quality and good insulating properties of ozone-based films. However, further optimization of the ALD technique with ozone is needed as a relatively low relative permittivity characterizes the ultra-thin films.

This study is devoted to the technology and optimization of pulsed-DC reactive magnetron sputtering of hafnium oxynitride (HfOxNy) thin-films. The fabrication process of HfOxNy films was optimized employing the Taguchi orthogonal tables approach leading to the material with possible best electrical parameters. During the opti-mization procedure, the parameters of dielectric films were monitored by means of electrical characterization of MIS structures with hafnium oxynitride as the gate-dielectric. The thermal stability of fabricated HfOxNy layers was also examined. The presented results have shown the improved electrical parameters of fabricated films after thermal treatment. Namely, we have observed beneficial flat-band voltage (V-fb) value, the disappearance of frequency dispersion of C-V characteristics, reduced effective charge (Q(eff)/q), and interface traps (D-it) densities of examined MIS structures. However, the permittivity value is slightly lower as compared to reference samples. The superior stability of HfOxNy layers up to 800 degrees C was proved. Although the significant increase of crystalline phase in the layer bulk was observed, no deterioration of electrical properties or surface morphology has been noticed. The results presented in this study make the investigated HfOxNy fabricated using pulsed-DC reactive magnetron sputtering the possible candidate as a gate dielectric in MIS structures and devices.

Colloidal cubic silicon-carbide nanocrystals have been fabricated, characterized, and introduced into metal–insulator–semiconductor and metal–insulator–metal structures based on hafnium oxide layers. The fabricated structures were characterized through the stress-and-sense measurements in terms of device capacitance, flat-band voltage shift, switching characteristics, and retention time. The examined electrical performance of the sample structures has demonstrated the feasibility of the application of both types of structures based on SiC nanoparticles in memory devices.