Papers by Salvador Dueñas
ECS Transactions, 2021
This work deals with the thermoelectric characterization of commercial lead zirconate titanate (P... more This work deals with the thermoelectric characterization of commercial lead zirconate titanate (PZT) based piezoelectric diaphragms. An in-depth analysis of the piezo- and ferroelectric behavior of the samples was carried out by measuring current voltage curves and polarization hysteresis cycles in a wide temperature range. We demonstrate that, as the temperature decreases, higher electric fields are needed to completely polarize the sample. Furthermore, I-V measurements, polarization hysteresis loops and coercive fields allow us to confirm that the samples present different grain sizes. From impedance measurements, resonance frequency values, capacitance and permittivity were determined at temperatures ranging from 100 to 320 K. It is shown that impedance maxima shift towards greater frequency values when decreasing the temperature, which is mainly attributed to the appearance of an internal stress that generates larger stiffness in the ceramic. Finally, an electroacoustic characte...
ECS Transactions, 2021
The use of thin layers of amorphous hafnium oxide has been shown to be suitable for the manufactu... more The use of thin layers of amorphous hafnium oxide has been shown to be suitable for the manufacture of Resistive Random-Access memories (RRAM). These memories are of great interest because of their simple structure and non-volatile character. They are particularly appealing as they are good candidates for substituting flash memories. In this work, the performance of the MIM structure that takes part of a 4 kbit memory array based on 1-transistor-1-resistance (1T1R) cells was studied in terms of control of intermediate states and cycle durability. DC and small signal experiments were carried out in order to fully characterize the devices, which presented excellent multilevel capabilities and resistive-switching behavior.
Capacitance Spectroscopy of Semiconductors, 2018
Solid-State Electronics, 2021
In this work, we have studied the set and the reset transitions in hafnium oxide-based metal-insu... more In this work, we have studied the set and the reset transitions in hafnium oxide-based metal-insulator-metal ReRAM devices using a capacitor discharge. Instead of applying a conventional voltage or current signal, we have discharged a capacitor through the devices to perform both transitions. In this way, both transitions are shown to be controllable. An accumulative process is observed if we apply consecutive discharges, and, when increasing the capacitor voltage in each discharge, the transitions between both resistance states are complete. In addition, it has been shown that faster transitions require larger capacitor voltages. Manuscript file_Not revised Click here to view linked References
Journal of Alloys and Compounds, 2020
Two-component crystalline thin film structures consisting of continuous ε-Fe 2 O 3 bottom layers ... more Two-component crystalline thin film structures consisting of continuous ε-Fe 2 O 3 bottom layers followed by top layers of BiOCl nanoflakes were grown using atomic layer deposition from FeCl 3 and BiCl 3 at 375 C. Si(100) planar wafer, three-dimensional Si structures and conductive TiN/Si were exploited as substrates. Electrical measurements revealed that the deposited structures were moderately leaky, as the structures showed rectifying behavior affected by visible illumination. Magnetization in these films in the as-deposited state was nonlinear, saturative, and exhibited well-defined coercive fields. Annealing changed the surface morphology, phase composition and reduced the magnetic behavior of the thin films.
ECS Meeting Abstracts, 2020
Nowadays, there is an increasing interest in the fabrication of neuristors in which memristors ar... more Nowadays, there is an increasing interest in the fabrication of neuristors in which memristors are used to create a neuron-like behavior (1). Memristors based on resistive switching memories (RRAM) are promising candidates to implement artificial synaptic devices for their use in neuromorphic systems, due to their high number or reachable conductance levels. In a previous work (2) we show that TiN/Ti/ HfO2/W capacitors exhibit resistive switching behavior and that intermediate conductance states can be obtained by varying the voltage applied to the device (Voltage-control mode, VCM). We demonstrated that the conductance values vary near linearly when applying voltage depression pulses. During depression process, the conductance state depends on the amplitude and the duration of the voltage pulses length. Moreover, this process is accumulative: the conductance decreases when applying successive pulses of same amplitude and length. In contrast, the potentiation characteristic is not l...
IEEE Journal of the Electron Devices Society, 2020
Due to the high number of reachable conductance levels in resistive switching devices, they are g... more Due to the high number of reachable conductance levels in resistive switching devices, they are good candidates to implement artificial synaptic devices. In this work, we have studied the control of the intermediate conductance levels in HfO 2-based MIM capacitors using current pulses. The set transition can be controlled in a linear way using this kind of signal. The potentiation characteristic is not affected by the pulse length due to the filament formation takes place in very short times. This behavior does not allow using identical pulses to obtain the potentiation characteristic. The transient response of the devices when applying current pulses showed the filament formation is characterized by a peak in the voltage transient signal. No depression characteristic can be obtained using current signals due to the abrupt reset transition. However, the depression characteristic can be obtained using voltage pulses, so combining both signals should allow control the synaptic weight in an appropriate way.
Nanotechnology, 2020
Amorphous SiO2-Nb2O5 nanolaminates and mixture films were grown by atomic layer deposition. The f... more Amorphous SiO2-Nb2O5 nanolaminates and mixture films were grown by atomic layer deposition. The films were grown at 300 o C from Nb(OC2H5)5, Si2(NHC2H5)6, and O3 to thicknesses ranging from 13 to 130 nm. The niobium to silicon atomic ratio was varied in the range of 0.11-7.20. After optimizing the composition, resistive switching properties could be observed in the form of characteristic current-voltage behavior. Switching parameters in the conventional regime were well defined only in a SiO2:Nb2O5 mixture at certain, optimized, composition with Nb:Si atomic ratio of 0.13, whereas low-reading voltage measurements allowed recording memory effects in a wider composition range.
ECS Journal of Solid State Science and Technology, 2017
CoFe 2 O 4 nanoparticles with 3-30 nm in diameter were synthesized by sol-gel method. The particl... more CoFe 2 O 4 nanoparticles with 3-30 nm in diameter were synthesized by sol-gel method. The particles were spread as a solid discontinuous layer over planar silicon and TiN substrates by spin coating and covered by 15 nm thick ZrO 2 films by atomic layer deposition. Crystal structures distinctively characteristic of CoFe 2 O 4 and ZrO 2 constituents were preserved. The nanocomposite CoFe 2 O 4-ZrO 2 layers demonstrated dielectric polarization, saturative magnetization, and implications of resistive switching behavior. Behavior most clearly attributed to memory materials was observed in the field admittance characteristic with two distinct states in susceptibility of the nanocomposite.
ACS Omega, 2017
Mixed films of a high-permittivity oxide, Er 2 O 3 , and a magnetic material, Fe 2 O 3 , were gro... more Mixed films of a high-permittivity oxide, Er 2 O 3 , and a magnetic material, Fe 2 O 3 , were grown by atomic layer deposition on silicon and titanium nitride at 375°C using erbium diketonate, ferrocene, and ozone as precursors. Crystalline phases of erbium and iron oxides were formed. Growth into three-dimensional trenched structures was demonstrated. A structure deposited using tens to hundreds subsequent cycles for both constituent metal oxide layers promoted both charge polarization and saturative magnetization compared to those in the more homogeneously mixed films.
ECS Journal of Solid State Science and Technology, 2018
Thin mixed and nanolaminate films of ZrO2 and Al2O3 were grown by atomic layer deposition from th... more Thin mixed and nanolaminate films of ZrO2 and Al2O3 were grown by atomic layer deposition from the corresponding metal chlorides and water. The films were grown at 350 o C in order to ensure ZrO2 crystallization in the as-deposited state. The relative thicknesses of layers in the structure of the nanolaminates were controlled in order to maximize the content of metastable polymorphs of ZrO2 that have higher permittivity than that of the stable monoclinic ZrO2. The multilayer films demonstrated interfacial charge polarization and saturative magnetization in external fields. The conductivity of the films could be switched between high and low resistance states by applying voltages of alternating polarity.
Thin Solid Films, 2018
Introduction Nanostructured Co3O4 in thin film form may possess and demonstrate a variety of prop... more Introduction Nanostructured Co3O4 in thin film form may possess and demonstrate a variety of properties making the material attractive for several applications. Co3O4 has been investigated as an important electrode material [1-4], gas sensor [5, 6], catalyst [7, 8], or superhydrophobic coating [9]. Co3O4 films have demonstrated resistive switching properties potentially enabling their application in resistive random access memory devices [10, 11]. Cobalt oxide, Co3O4, containing Co 2+ and Co 3+ ions, is recognized as magnetic semiconductor material [12]. Antiferromagnetic behavior with characteristic magnetization-field curves can be demonstrated by Co3O4 nanoparticles [13]. Regarding the possible applications in spintronics, it may occur necessary to activate ferromagnetic coupling in Co3O4 nanoparticles by hybridization with foreign materials, e.g. graphene oxide [14]. Co3O4 films have been grown by oxidation of electron-beam evaporated Co layers [15], pulsed laser deposition [5, 10] chemical bath deposition [1, 6], chemical solution deposition [8, 11], hydrothermal method [2, 13], solvothermal synthesis [9], spray pyrolysis [16]
Beilstein journal of nanotechnology, 2018
Thin solid films consisting of ZrOand FeOwere grown by atomic layer deposition (ALD) at 400 °C. M... more Thin solid films consisting of ZrOand FeOwere grown by atomic layer deposition (ALD) at 400 °C. Metastable phases of ZrOwere stabilized by FeOdoping. The number of alternating ZrOand FeOdeposition cycles were varied in order to achieve films with different cation ratios. The influence of annealing on the composition and structure of the thin films was investigated. Additionally, the influence of composition and structure on electrical and magnetic properties was studied. Several samples exhibited a measurable saturation magnetization and most of the samples exhibited a charge polarization. Both phenomena were observed in the sample with a Zr/Fe atomic ratio of 2.0.
Journal of molecular modeling, 2017
The over-expression of immune-suppressors such as IL-10 is a crucial landmark in both tumor progr... more The over-expression of immune-suppressors such as IL-10 is a crucial landmark in both tumor progression, and latent viral and parasite infection. IL-10 is a multifunctional protein. Besides its immune-cell suppressive function, it also promotes B-cell tumorigenesis of lymphomas and melanoma. Human pathogens like unicellular parasites and viruses that remain latent inside B cells promote the over-expression of hIL-10 upon infection, which inhibits cell-mediated immune surveillance, and at the same time mediates B cell proliferation. The B-cell specific oncogenic latent virus Epstein-Barr virus (EBV) encodes a viral homologue of hIL-10 (ebvIL-10), expressed during lytic viral proliferation. Once expressed, ebvIL-10 inhibits cell-mediated immune surveillance, assuring EBV re-infection. During long-term latency, EBV-infected B cells over-express hIL-10 to assure B-cell proliferation, occasionally inducing EBV-mediated lymphomas. The amino acid sequences of hIL-10 and ebvIL-10 are more t...
Molluscan Research, 2016
ABSTRACT We investigated three species of Conidae, one on the western shores of Baja California (... more ABSTRACT We investigated three species of Conidae, one on the western shores of Baja California (Californiconus californicus), and two in the Gulf of California (Conasperella perplexus and Conasperella ximenes). In a thermal horizontal gradient trial with day–night cycles, we determined the final thermal preference of three species of snails. Californiconus californicus had a preferred average temperature of 23.3 °C, compared with 22.7 °C for Co. perplexus whereas Co. ximenes had a diel preference of 20.1 °C during the day and 27.2 °C at night. The displacement velocity in Ca. californicus during the day was 12.6 ± 1.9 cm h−1 versus 17.6 ± 2 cm h−1 at night; for Co. perplexus it was 3.8 ± 0.67 cm h−1 in the day and 4.16 ± 0.72 cm h−1 at night; and for Co. ximenes it was 19.3 ± 2.5 cm h−1 during the day and 18.3 ± 2.6 cm h−1 during the night. The critical thermal maximum, the temperature at which at least 50% of the experimental group experiences a loss of attachment, differed between Conasperella species from the Gulf of California and Californiconus californicus from the Eastern Pacific Ocean. The species inhabiting the Gulf of California have a greater thermal tolerance, with this pattern typical of species in tropical seas, whereas some of those that inhabit the Pacific coast of North America can tolerate lower temperatures, reflecting their range in more temperate climates.
Microelectronics Reliability, 2014
ABSTRACT The post-breakdown conduction characteristics of holmium titanium oxide (HoTiOx)-based m... more ABSTRACT The post-breakdown conduction characteristics of holmium titanium oxide (HoTiOx)-based metal-insulator-metal capacitors fabricated by the atomic layer deposition technique on Si substrates were investigated. Diode-like and power-law models were fitted to the experimental current-voltage (I-V) curves and the results assessed with the aim of detecting any possible correlation among the model parameters. It was found that the number of parameters involved can be reduced in both cases and that for the power-law model a single parameter is solely required to approximate the I-V curves in a wide current range (from 10−11 to 10−4 A). This property, which has also been observed in a variety of material systems, was used to simulate the bipolar switching behavior exhibited by the I-V characteristics. The connection with the physics of electron transport through atom-sized constrictions is discussed.
Solid-State Electronics, 1989
Airstrati-The Constant-Capacitance Deep-Level Optical Spectroscopy (CC-DLOS) is a modilkation of ... more Airstrati-The Constant-Capacitance Deep-Level Optical Spectroscopy (CC-DLOS) is a modilkation of the DLOS (Deep-Level Optical Spectroscopy) technique. Both methods enable separate measurement of the spectral distributions a#v) and a"(hv) of the optical electron and hole capture cross-sections of a deep centre in a semiconductor. The C&DLOS is based on the measurement of constant-capacitance photostimulated voltage transients of a junction after au electrical, thermal or optical excitation. The main advantage of CC-DLOS is that it allows to measure u,"Qv) and o,"(hv) even at high densities of deep centers. We have applied this technique to' the measurement of capture cross sections of Au levels in silicon.
Journal of Electronic Materials, 1992
The c-radiation effects on the electrical characteristics of metal-insulatorsemiconductor capacit... more The c-radiation effects on the electrical characteristics of metal-insulatorsemiconductor capacitors based on HfO 2 , and on the resistive switching characteristics of the structures have been studied. The HfO 2 was grown directly on silicon substrates by atomic layer deposition. Some of the capacitors were submitted to a c ray irradiation using three different doses (16 kGy, 96 kGy and 386 kGy). We studied the electrical characteristics in the pristine state of the capacitors. The radiation increased the interfacial state densities at the insulator/semiconductor interface, and the slow traps inside the insulator near the interface. However, the leakage current is not increased by the irradiation, and the conduction mechanism is Poole-Frenkel for all the samples. The switching characteristics were also studied, and no significant differences were obtained in the performance of the devices after having been irradiated, indicating that the fabricated capacitors present good radiation hardness for its use as a RS element.
Journal of Applied Physics, 1998
We have obtained Al/SiNx:H/InP metal-insulator-semiconductor devices depositing SiNx:H thin films... more We have obtained Al/SiNx:H/InP metal-insulator-semiconductor devices depositing SiNx:H thin films by the electron cyclotron resonance plasma method at 200 °C. The electrical properties of the structures were analyzed according to capacitance–voltage and deep level transient spectroscopy measurements. We deduce an inverse correlation between the insulator composition—the N/Si ratio—and the density of interface traps: those films with the maximum N/Si ratio (1.49) produce devices with the minimum trap density—2×1012 cm−2 eV−1 at 0.42 eV. above the midgap. We explain the influence of film composition on the interface trap density in terms of a substitution of phosphorous vacancies at the InP surface, Vp, by N atoms coming from the insulator, NVp. The values obtained in our research for the interface trap distribution were similar to other published results for devices that use chemical and/or physical passivation processes of the InP surface prior to the deposition of the insulator.
2020 IEEE Latin America Electron Devices Conference (LAEDC), 2020
Three topologies of TiN/Ti/HfO2/W resistive switching memories (RRAM) are proposed in this work: ... more Three topologies of TiN/Ti/HfO2/W resistive switching memories (RRAM) are proposed in this work: crossbar, isolated and isolated-crossbar configurations. All configurations use the same sequence of technological processes. The different topologies are obtained by customizing the layouts corresponding to the bottom electrode (W), and the silicon oxide layer that is deposited on the bottom electrode. A comparative study of the resistive switching mechanisms in the three configurations has been carried out. DC current-voltage cycles and small signal conductance memory maps of single RRAM show relevant differences among the three topologies. Complex structures containing various devices (series, anti-series, parallel, antiparallel) have also been fabricated. Switching loops and memory maps obtained for these complex structures demonstrate that they are fully operative, validating the technological route to manufacture complete RRAM memory chips.
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Papers by Salvador Dueñas