Francisco Servando Aguirre-Tostado

Francisco Servando Aguirre-Tostado
Centro de Investigación en Materiales Avanzados, S. C. · Unidad Monterrey

PhD

About

85
Publications
17,200
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2,061
Citations
Additional affiliations
June 2008 - present
Centro de Investigación en Materiales Avanzados, S. C.
Position
  • Professor (Full)
September 2004 - June 2008
University of Texas at Dallas
Position
  • Researcher

Publications

Publications (85)
Article
Most solution‐based synthetic routes for perovskite film deposition take place under highly controlled atmospheres and cannot be easily escalated for mass production. Here, the control in situ over luminescent, morphological, and structural characteristics of hybrid and inorganic perovskite films deposited on top of hot glass substrates by multisou...
Article
Full-text available
The application of new technologies for treatments against different diseases is increasingly innovative and effective. In the case of nanomedicine, the combination of nanoparticles with biological membranes consists of a "camouflage" technique, which improves biological interaction and minimizes the secondary effects caused by these remedies. In t...
Article
Full-text available
Zinc oxide (ZnO) thin films were grown at 70 °C by plasma-enhanced atomic layer deposition using H2O and O2 plasmas. Plasma oxidants were used in order to improve the ZnO crystallinity and optoelectronic properties, avoiding high-temperature synthesis. The deposition parameters were optimized to achieve saturation in each reaction step. X-ray photo...
Article
Cu2SnS3 (CTS) thin films were grown by spray pyrolysis using two synthetic routes: stoichiometric and substoichiometric in an aprotic media. The use of dimethyl sulfoxide (DMSO) as a solvent improved the solubility of metal chlorides at room temperature, which was crucial to avoid metal-hydroxylation. In this sense, a mechanism for the solvation of...
Article
Full-text available
The diagnosis of diseases based on immunosensors have been objective of research in the last years, providing an improvement for a rapid detection, high sensitivity, precision, accuracy, specificity and resolution. Areas of progress such as analytical technologies, interpretation and standardization has been done for common biomarkers. However, yea...
Article
In this work, we reported the synthesis of copper oxide (CuO) thin films by sol-gel process assisted by spin coating technique at room temperature. Chemical characterization of CuO precursor solution was determined by Fourier Transformed Infrared Spectroscopy (FTIR) and thermal stability by Thermogravimetric/ Differential Scanning Calorimetry Analy...
Article
Carbon surfaces become significantly activated with plasma treatment enhancing the surface energy, wettability, and bio-conjugation. However, the activated surfaces are influenced by aging effect or reorientation phenomenon, a rarely reported occurrence, that refers to the loss of surface activity with time. Generated plasma-activated surface funct...
Article
Based on the concept of LEGO toys, a fiber probe analytical platform (FPAP) was developed as a powerful diagnostic tool offering higher sensitivity in detection of infectious agents compared to established methods. Using the form and the function of LEGO toys, this protocol describes a fiber-based, 96-well plate, which suspends a new class of chemi...
Article
The synthesis and characterization of Cu2ZnSnS4 (CZTS) thin films prepared on glass/CdS substrates by the successive ionic layer adsorption and reaction (SILAR) method are presented. The effect of copper concentration and atmosphere annealing on the properties of CZTS thin films were studied by means X-ray diffraction (XRD), Raman spectroscopy, Sca...
Article
Full-text available
This study explores magnetization exhibited by nanoscale platinum-based structures embedded in pure silica plates. A superposition of laser pulses in the samples produced periodic linear arrangements of micro-sized structures. The samples were integrated by PtO2 microstructures (PtOΣs) with dispersed Pt oxide nanoparticles in their surroundings. Th...
Article
The adsorption and reaction mechanisms of Cu2ZnSnS4 (CZTS) quaternary compound deposited by the Successive Ionic Layer Adsorption and Reaction (SILAR) method are discussed. The understanding of nucleation and growth mechanisms of this material will improve the control of composition, homogeneity and final properties of the obtained thin films. Ther...
Poster
Full-text available
The detection of demyelinating diseases, such as multiple sclerosis, is commonly based on enzyme-linked immunosorbent assays (ELISA) and magnetic resonance imaging (MRI) according to the McDonald diagnostic criteria. However, this kind of studies require several days to obtain determinant results, leading to the implementation of biosensors to impr...
Article
The present study outlines the evolution of the composition, strain and electrical properties of cadmium sulfide (CdS)thin films deposited via pulsed laser deposition (PLD), under varied chamber pressure ranging from 0.13 to 13.33 Pa. The CdS thin films presented a hexagonal crystalline structure at the various deposition pressures as well as impro...
Article
Cadmium sulfide is the main choice among n-type semiconductors for several solar cell technologies due to its excellent optical, structural and electronic characteristics. Even when it has been widely studied, there are still unsolved aspects related with the understanding of nucleation and growth mechanisms. For that, the initial growth stages of...
Article
Background: Synthesis and applications of Ag-coated carbon nanotubes are currently under intensive research, resulting in a series of recent patents. Silver nanoparticles are normally obtained from silver nitrate. However, there are also other silver-containing compounds that can facilitate the production of silver nanoparticles, such as silver(I)...
Article
Cadmium sulfide (CdS) thin films as n-type semiconductor material were deposited by pulsed laser deposition by varying the argon pressure at room temperature. The structural, morphological and stoichiometric characteristics of the CdS films were studied as a function of the deposition pressure. The results show that the argon deposition pressure ha...
Article
Full-text available
In this work, we report the synthesis and purification of polyvinyl alcohol-polyaniline (PVA–PANI) copolymers at different aniline concentrations, and their molecular (1H-NMR and FTIR), thermal (TGA/DTG/DSC), optical (UV–Vis-NIR), and microstructural (XRD and SEM) properties before and after activation with glutaraldehyde (GA) in order to obtain an...
Presentation
Full-text available
Multilayer studies have been carried out through the years in order to get a standardized process to control the thickness of a thin film and observe the interface effects that this carries. Even though multilayers of conductive polymers, such as polyaniline, have been object of research for years, a study for the reported polyaniline-polyvinyl alc...
Article
Zinc oxide films with a high transmittance in the visible range (over 80%) were obtained by successive ionic layer adsorption and reaction method without thermal treatment, using only a low-temperature (125 °C) ethylene glycol bath to complete the reaction. It was shown that the film deposition rate, as well as its structural and optical properties...
Article
Currently, the research in absorber films for solar cells is focused on the development of non-toxic, low-cost, and high-available materials. Thus, the CuSbS2 phase of the Cu-Sb-S system is promising due to its attractive optoelectronic properties. Chalcostibite thin films have been deposited by several approaches, however, their synthesis, as a pr...
Article
The background in X-ray photoelectron spectroscopy data originates, partially, from inelastically scattered photoelectrons. In fact, the current theoretical methods for calculating the background intensity are based on electron energy losses. However, a critical part of the experimental signal, which is known as the Shirley background, cannot be de...
Article
Thin films of the covellite phase of CuS are of special importance due to their properties for optoelectronic device applications. Their preparation by chemical solution methods could enable their deposition on flexible substrates at low temperature for large area applications. Successive Ionic Layer Adsorption and Reaction (SILAR) is a promising o...
Poster
Full-text available
Polyaniline (PANI) has been one of the most studied conducting polymers in the past 30 years because of its interesting properties such as tunable electrical conductivity and good thermal and environmental stability. Reported synthesis methods of PANI focus on the chemical and electrochemical oxidation of the aniline monomer to obtain PANI in emera...
Presentation
Full-text available
Although it has been more than 15 years of research focused on the synthesis and characterization of polyvinyl alcohol-polyaniline (PVA-PANI) colloidal dispersions, the use of this material obtained by the chemical oxidation of aniline for biological applications has been almost overlooked for the electrochemical polymerization of aniline in Pt ele...
Poster
In the present study zeolite modified with zinc (Zn) were successfully synthesized by using microwave-assited and inmersed in simulated body fluid (SBF) for 14 days to determinate the bioactivity of the zeolitic material. With addition of Zn in the structure we gave new antibacterial and antimicrobial properties and at the same time reducing the co...
Chapter
Full-text available
The development of solution-based processes at low temperature and low cost makes zinc oxide attractive as a material for large area and flexible electronics applications. A process for the deposition of 3D flower-like structures of ZnO on glass substrates with luminescent properties is presented. The lily flower-like ZnO structures were deposited...
Article
Functionalized graphene oxide papers are assembled materials with a wide range of potential applications; however, scientific studies about how the physical properties of functionalized graphene oxide papers are affected by the presence of new functional groups have not been addressed. Here, electrical resistance, optical band gap, and mechanical p...
Article
The early stages of the oxidation of the Si[001] 2 × 1 surface were studied with synchrotron radiation photoelectron spectroscopy. The analysis was based on the block approach, which is a refinement of spectra-subtraction that accounts for changes on the background signal and for band-bending shifts. By this method, it was possible to robustly show...
Article
Full-text available
In this work, multiwall carbon nanotubes (MWCNT) were functionalized with silver nanoparticles using twodifferent methods of incorporation. Characterization of these composites was done using Raman spectroscopy andTransmission Electron Microscopy (TEM) and the antibacterial properties were measured using method of dilutionand plating. The four-poin...
Conference Paper
Full-text available
In the last years, the transparent conducting oxides (TCOs) thin films have been widely studied because of their potential applications in piezoelectric transducers, gas sensors, solar cells and other optoelectronic devices. Tin doped indium oxide (ITO) is widely used due to its electrical and optical properties; however, indium is a toxic, scarcel...
Article
According to the reports of Z.E. Horvath et al [1] and Liu Yun-quan et al [5], carbon nanotubes can be synthesized by spray pyrolysis from different carbon sources (n-pentane, n-hexane, n-heptane, cyclohexane, toluene and acrylonitrile) and several metallocene catalysts (ferrocene, cobaltocene and nickelocene). This paper describes two different ex...
Article
Full-text available
Blue corn is a potential material for expanded snack production. Whole blue corn meal was mixed with corn starch and processed by extrusion to produce a third-generation snack. Optimum extrusion conditions were calculated with the response surface methodology using expansion index (EI), penetration force (PF), specific mechanical energy (SME) and t...
Article
Full-text available
In this paper, we report a feasibility study of MuGFETs (multi-gate field effect transistors) devices using solution-based cadmium sulfide films as the semiconductor. The simulations were carried out using the commercially available ATLAS simulator. Experimental parameters for CdS were extracted from planar thin film transistors fabricated using ph...
Article
Full-text available
Cadmium sulfide (CdS) thin films have been deposited by chemical bath deposition (CBD) at 70°C on glass substrates. In order to have a better control of deposition rate in CdS synthesis, Sodium borohydride and hydrazine were demonstrated as novel complexing agents. The structural, optical and electricalcharacteristics of the CdS thin films obtained...
Article
Full-text available
Lead sulfide (PbS) thin films were prepared by chemical bath deposition (CBD) as function of deposition time, pH and deposition rate and the impact of the resulting film structure on the thin film transistor (TFT) electrical characteristics was evaluated. Structure and morphology were investigated by X-ray diffraction (XRD) and scanning electron mi...
Article
Full-text available
Cadmium sulphide semiconductor thin films have been deposited by chemical bath technique (70°C) on HfO2 substrates. The effect of pH on deposition rate was studied to determine the optimum condition for deposition. CdS films were deposited at pH ranging from 10 to 11.9 in an ammonia-free CBD process employing sodium citrate dihydrate and potassium...
Article
Zinc Oxide (ZnO) Thin-Film Transistors (TFTs) using Aluminum (Al) and Aluminum-doped zinc Oxide (AZO) as Source-Drain (S-D) contacts are reported. The fabrication process was carried out using five photolithography steps with a maximum processing temperature of 100°C, which makes the process compatible with flexible/transparent applications. The AZ...
Conference Paper
In this paper, we report the development of low power and low temperature zinc oxide (ZnO)-based inverters. Logic inverters were evaluated as function of gate dielectric thicknesses and several operation bias voltages. Hafnium oxide (HfO2) was used as gate dielectric. The HfO2 dielectric thickness was evaluated from 15 to 90 nm. TFTs carrier mobili...
Article
In this work, we demonstrate a full bridge diode (FBD) circuit compatible and fabricated on flexible polyethylene naphthalene (PEN) substrate. The fabrication was carried out using photolithography-based processes and pentacene Schottky diodes as the active circuit components. The individual pentacene diodes show the on/off current ratio of 105, wi...
Article
Full-text available
The Al2O3/GaAs and HfO2/GaAs interfaces after atomic layer deposition are studied using in situ monochromatic x-ray photoelectron spectroscopy. Samples are deliberately exposed to atmospheric conditions and interfacial oxide re-growth is observed. The extent of this re-growth is found to depend on the dielectric material and the exposure temperatur...
Article
The angular dependence of the X-ray photoelectron spectroscopy (XPS) signal is influenced not only by the electron take-off angle, but also by instrument-related geometrical factors. The XPS signal is, in fact, integrated over the overlap between the X-ray beam, the spectrometer analysis volume, and the sample surface. This overlap depends on the s...
Article
The passivation of III–V semiconductor materials with sulphur is widely reported to reduce interface state defects and improve semiconductor device performance. The most common approach utilises ammonium sulphide ((NH4)2S), however there are wide variations in the reported processing parameters involved in this procedure. This study provides a comp...
Article
Full-text available
The structure of 3 nm and 15 nm diamond-like carbon films, grown on Si(001) by filtered cathodic arc, was studied by angle-resolved X-ray photoelectron spectroscopy (ARXPS) and transmission electron microscopy (TEM). The ARXPS data was deconvolved by employing simultaneous-fitting, which allowed for a clear deconvolution of the Si 2p and C 1s spect...
Article
Full-text available
A summary of the workshop entitled ‘Angle-Resolved XPS: The Current Status and Future Prospects for Angle-resolved XPS of Nano and Subnano Films’ is given, which was held at the Riviera Maya, Mexico, 26–30 March 2007, under the main sponsorship of the International Union for Vacuum Science, Technique and Applications (IUVSTA). Angle-resolved X-ray...
Article
Molecular electronics is an attractive option for low-cost devices because it involves highly uniform self-assembly of molecules with a variety of possible functional groups. However, the potential of molecular electronics can only be turned into practical applications if reliable contacts can be established without damaging the organic layer or co...
Article
Full-text available
The controlled addition of La to Hf <sub>x</sub> Si <sub>1-x</sub> O <sub>2</sub>/ SiO <sub>2</sub>/ Si dielectric stacks has been shown to enable the engineering of the work function to appropriate levels when TaN or TiN is employed as the capping metal gate. Work function tuning has been suggested to be controlled by La diffusion into the Hf-base...
Article
Full-text available
The passivation of interface states remains an important problem for III-V based semiconductor devices. The role of the most stable bound native oxides GaOx (0.5 ≤ x ≤ 1.5) is of particular interest. Using monochromatic x-ray photoelectron spectroscopy in conjunction with controlled GaAs(100) and InGaAs(100) surfaces, a stable suboxide (Ga2O) bond...
Article
We examine the characteristics of TaLaN metal gates in direct contact with HfO2 dielectric, in particular focusing on the effect of La in the gate stack for NMOS applications. Effective work functions (EWF) and vacuum work functions (WF) are measured as a function of lanthanum content in TaLaN without any intentional heating using X-ray photoelectr...
Article
Full-text available
“Half-cycle” atomic layer deposition reactions of trimethyl aluminum (TMA) and water on GaAs exposed to wet chemical sulfur treatments are studied for the formation of Al2O3. Trivalent oxides of gallium and arsenic are completely reduced following the first TMA pulse. The same processing step also removes As–S bonding below the level of detection,...
Article
Full-text available
We report on the stability under rapid thermal annealing (RTA) of the nitrogen depth profile in nitrided HfO <sub>2</sub>/ SiO <sub>2</sub>/ Si [001] and Hf <sub>0.8</sub> Si <sub>0.2</sub> O <sub>2</sub>/ SiO <sub>2</sub>/ Si [001] dielectric stacks. High resolution x-ray photoelectron spectroscopy (XPS) data indicate that the chemical component o...
Article
Full-text available
The reduction in III-V interfacial oxides by atomic layer deposition of Al(2)O(3) on InGaAs is studied by interrupting the deposition following individual trimethyl aluminum (TMA) and water steps (half cycles) and interrogation of the resultant surface reactions using in situ monochromatic x-ray photoelectron spectroscopy (XPS). TMA is found to red...
Article
Full-text available
The surface reactions of LaxAl2−xO3 ultrathin films deposited on atomically clean In0.2Ga0.8As by atomic layer deposition are studied by in situ high resolution x-ray photoelectron spectroscopy. Using 1:2 alternating cycles of La2O3 and Al2O3 results in a La:Al concentration ratio of 1:10. We found that the LaxAl2−xO3/InGaAs interface consisted of...
Article
Full-text available
The electrical characteristics of n- and p-type gallium arsenide (GaAs) capacitors show a striking difference in the “accumulation” capacitance frequency dispersion. This difference has been attributed by some to a variation in the oxide growth, possibly due to photoelectrochemical properties of the two substrates. We show that the oxide growth on...
Article
Full-text available
A systematic study of the interface engineering and dielectric properties of nanolaminated hafnium aluminate on GaAs is presented. The dielectrics were deposited using atomic layer deposition of alternating cycles of HfO2 and Al2O3 on GaAs substrates. High resolution x-ray photoelectron spectroscopy (XPS) showed differences in space charge amounts...
Article
Full-text available
Atomic H exposure of a GaAs surface at 390 °C is a relatively simple method for removing the native oxides without altering the surface stoichiometry. In-situ reflection high energy electron diffraction and angle-resolved x-ray photoelectron spectroscopy have been used to show that this procedure applied to In0.2Ga0.8As effectively removes the nati...
Article
Full-text available
The reduction and removal of surface oxides from GaAs substrates by atomic layer deposition (ALD) of Al2O3 and HfO2 are studied using in situ monochromatic x-ray photoelectron spectroscopy. Using the combination of in situ deposition and analysis techniques, the interfacial "self-cleaning" is shown to be oxidation state dependent as well as metal o...
Article
The percentage of uncovered area in ultrathin diamond-like carbon (DLC) films on Si(001) wafers, which assesses the pinhole density of the carbon films, was quantified through angle-resolved X-ray photoelectron spectroscopy. The uncovered areas of the silicon substrate are oxidized upon contact with air, so the photoelectron signal from Si+4 could...