Layered nanolaminate ternary carbides, nitrides and carbonitrides with general formula Mn+1AXn or MAX (n = 1, 2, or 3, M is an early transition metal, A is mostly group 13 or 14 element, and X is C and/or N) has revolutionized the world of nanomaterials, due to the coexistence of both ceramic and metallic nature, giving rise to exceptional mechanical, thermal, electrical, chemical properties and wide range of applications. Although several solid-state bulk synthesis methods have been developed to produce a variety of MAX phases, however, for certain applications, the growth of MAX phases, especially in its high-quality epitaxial thin films form is of increasing interest. Here, we summarize the progress made thus far in epitaxial growth and property evaluation of MAX phase thin films grown by various deposition techniques. We also address the important future research directions to be made in terms of thin-film growth. Overall, in the future, high-quality single-phase epitaxial thin film growth and engineering of chemically diverse MAX phases may open up interesting new avenues for next-generation technology.
We present an efficient and general method to identify promising candidate configurations for thin-film oxides and to determine structural characteristics of (metastable) thin-film structures using ab initio calculations. At the heart of this method is the complexity of the oxide bulk structure, from which a large number of thin films with structural building blocks, that is motifs, from metastable bulk oxide systems can be extracted. These span a coarse but well-defined network of initial configurations for which density functional theory (DFT) calculations predict and implement dramatic atom…
In this work, we studied amorphous carbon ($a$-C) thin films deposited using direct current (dc) and high power impulse magnetron sputtering (HiPIMS) techniques. The microstructure and electronic properties reveal subtle differences in $a$-C thin films deposited by two techniques. While, films deposited with dcMS have a smooth texture typically found in $a$-C thin films, those deposited with HiPIMS consist of dense hillocks surrounded by a porous microstructure. The density of $a$-C thin films is a decisive parameter to judge their quality. Often, x-ray reflectivity (XRR) has been used to meas…
Different thicknesses of cobalt thin films were growth by magnetron sputtering deposition techniques. The films thicknesses were determinated with X ray Photoelectron Spectroscopy (XPS) and Quartz Crystal Monitoring (QCM). XPS is also used to determinate the films quality. The films magnetic properties were determinated by Ferromagnetic Resonance (FMR) technique.
We report on the synthesis of perovskite SrIrO3 thin films using sputtering technique. Single phase (110) oriented SrIrO$_3$ thin films were epitaxially grown on SrTiO3 (001) substrate. Using off-axis XRD $θ-2θ$ scans, we demonstrate that these films exhibit (110) out-of-plane orientation with (001) and (1-10) lying in-plane. The sputtering grown thin films have a smooth, homogeneous surface, and excellent coherent interface with the substrate.
Direct magnetization measurements of thin gold films are presented. These measurements integrate the signal from the thin film under study and the magnetic contribution of the film's interface with the substrate. The diamagnetic contribution to the signal from the bulk substrate is of the same order as the noise level. we find that thin gold films can exhibit positive magnetization. The character of their magnetic behavior is strongly substrate dependent.
Magnetron sputtering has also been used to deposit thin films of some materials and it has significant technological importance. A modeling on deposition of epitaxial thin films of Yttrium Stabilized Zirconia (YSZ) was done the diffusion of adatom on the surface were studies. There exists a strong interaction of ions formed in the plasma during the sputtering process. Cu thin films were deposited on Si. Nanocomposite thin film of SiCN showed dendritic growth.
Thin film quasicrystal coatings have unique properties such as very high electrical and thermal resistivity and very low surface energy. A nano quasicrystalline thin film of icosahedral Al-Ga-Pd-Mn alloy, has produced by flash evaporation followed by annealing. Attempts will be made to discuss the micromechanisms for the formation of quasicrystalline thin film in Al-Ga-Pd-Mn alloys
In this paper we investigate the influence of the substrate material and film thickness on the Peierls transition temperature in tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) thin films, grown by physical vapor deposition. Our analysis shows that the substrate material and the growth conditions strongly influence the film morphology. In particular, we demonstrate that the Peierls transition temperature in thin films is lower than in TTF-TCNQ single crystals. We argue that this effect arises due to defects, which emerge in TTF-TCNQ thin films during the growth process.
We demonstrate high performance chemical bath deposited CdS thin-film transistors TFTs using atomic layer deposited ZrO2 based high-k gate dielectric material.
Ba7Ir3O13+δ in thin film form is discovered. These films are characterized by colossal permittivity (CP) ~104 at room temperature, attributable to the colossal internal barrier layer capacitance effect at atomically thin domain boundaries. These findings suggest a new route to seeking novel CP materials through designing atomically thin domain boundaries.
The lattice of (001)-oriented BiFeO$_3$ epitaxial thin film has been identified by synchrotron x-ray diffraction. By choosing proper scattering zones containing the fixed (001) reflection, we have shown that low-symmetry phases similar to a $M_A$ phase exist in the thin film at room temperature. These results demonstrate a change in phase stability from rhombohedral in bulk single crystals, to a modified monoclinic structure in epitaxial thin films.
Varying the substrate temperature changes structural and magnetic properties of spinel ferrite NZFO thin films. XRD of films grown at different temperature display only 004 reflections, without any secondary peaks, showing growth orientation along the c axis. We find an increase in crystalline quality of these thin films with the rise of substrate temperature. The surface topography of the thin films grown on various growth temperatures conditions reveal that these films are smooth with low roughness, however the thin films grown at 800 C exhibit lowest average and rms roughness among all thin…
A novel broad-band measurement method of the MI in thin films and ribbons is presented. It is based on the automated measurement of the reflection coefficient of a cell loaded with the sample. Illustrative results obtained with a permalloy multilayer thin film are presented and discussed.
Tin Sulphide (SnS) thin films have been recognized as a potential candidate for solar cells. Many fabrication techniques have been used to grow SnS thin films. The band-gap, ${\rm E_g}$ of SnS films as reported in literature, were found to vary from 1.2-2.5 eV depending on the film fabrication technique. The present work reports the structural, compositional, morphological and optical characterization of SnS thin films fabricated by thermal evaporation at room temperature. Results show that for the given fabrication technique/ condition, the band-gap functionally depends on the lattice paramet…
The phenomenon of potential sputtering of ultra-thin Pt films due to impact of 20 keV highly charged $Ar^{q+}$ (q = 3 - 8) ions has been investigated. The results show enhanced erosion of the Pt film with the increase of potential energy of the Ar projectile.
BiFeO3 thin films have been deposited on Pt/sapphire and Pt/Ti/SiO2/Si substrates with pulsed laser deposition using the same growth conditions, respectively. Au was sputtered as the top electrode. The microscopic structure of the thin film varies by changing the underlying substrate. Thin films on Pt/sapphire are not resistively switchable due to the formation of Schottky contacts at both the top and the bottom interface. However, thin films on Pt/Ti/SiO2/Si exhibit an obvious resistive switching behavior under forward bias. The conduction mechanisms in BiFeO3 thin films on Pt/sapphire and Pt…
We report studies of ferroelectricity in ultra-thin perovskite films with realistic electrodes. The results reveal stable ferroelectric states in thin films less than 10 Åthick with polarization normal to the surface. Under short-circuit boundary conditions, the screening effect of realistic electrodes and the influence of real metal/oxide interfaces on thin film polarization are investigated. Our studies indicate that metallic screening from the electrodes is affected by the difference in work functions at oxide surfaces. We demonstrate this effect in ferroelectric PbTiO$_3$ and BaTiO$_3$ fil…
An original modification of the standard Pulse Laser Deposition (PLD) method for preparing both undoped and indium doped zinc oxide (ZnO:In) thin films at low substrate temperature is proposed. This preparation method does not demand any further post-deposition annealing treatment of the grown films. The developed method allows to grow thin films at low substrate temperature that prevents them from the considerable loss of their intrinsic electrical and optical properties. The influence of deposition parameters on the electrical and optical parameters of the undoped and the indium doped ZnO th…
This paper discusses questions of synthesizing and pressing vanadium oxides to create film-forming materials that can be used in producing optical coatings. Based on the film-forming materials thus created, technological processes have been developed for fabricating coatings from vanadium dioxide by two methods of producing thin films: vacuum evaporation and magnetron sputtering. Questions of using films made from vanadium oxide in optical instrumentation are considered.
Far-infrared and terahertz spectroscopy of ferroelectric soft and central modes in thin films on substrates is reviewed. In addition to classical displacive proper ferroelectrics, also incipient and relaxor ferroelectrics and multiferroics are discussed. Special attention is paid to differences between the soft-mode behavior in thin films and bulk materials (ceramics and single crystals) and their influence on the low-frequency permittivity. Particularly the effects of the thin film strains and depolarizing electric fields of the probing waves on the grain boundaries are emphasized. The soft-m…
Ferroelectric materials with up-conversion luminescence (UCL) properties have potential opto-electric applications for display and sensing etc. Here, we demonstrate strong green UCL and enhanced electrical properties in Er3+-doped Na0.5Bi0.5TiO3 thin films. The thin films are prepared via using a modified chemical solution deposition method. These thin films are phase-pure and crystallized in perovskite structure. The largest remnant polarization (Pr) and highest dielectric constant are obtained from Na0.5Bi0.49Er0.01TiO3 thin films, and their values are 0.22 C/m2 and 1166, respectively. Meanw…
The temperature coefficients of the resistivity (TCR) of Cu, Ru, Co, Ir, and W thin films have been investigated as a function of film thickness below 10 nm. Ru, Co, and Ir show bulk-like TCR values that are rather independent of the thickness whereas the TCR of Cu increases strongly with decreasing thickness. Thin W films show negative TCR values, which can be linked to high disorder. The results are qualitatively consistent with a temperature-dependent semiclassical thin film resistivity model that takes into account phonon, surface, and grain boundary scattering.
Co and CoO thin films were deposited by magnetron sputtering in the form of multilayers. They were irradiated with Ar and Si ion beams of different energies and fluences. The magnetic properties were investigated.
A closed-form model is developed to evaluate the band-edge shift caused by quantum confinement for a two-dimensional non-parabolic carrier-pocket. Based on this model, the symmetries and the band-shifts of different carrier-pockets are evaluated for BiSb thin films that are grown along different crystalline axes. The phase diagrams for the BiSb thin film systems with different growth orientations are calculated and analyzed.
Here we report the adsorption behaviour of a water soluble laser dye rhodamine onto ultrathin films prepared by LB technique without altering its photophysical behabiour.
Epitaxial LaRh1/2Mn1/2O3 thin films have been grown on (001)-oriented LaAlO3 and SrTiO3 substrates using pulsed laser deposition. The optimized thin film samples are semiconducting and ferromagnetic with a Curie temperature close to 100 K, a coercive field of 1200 Oe, and a saturation magnetization of 1.7muB per formula unit. The surface texture, structural, electrical, and magnetic properties of the LaRh1/2Mn1/2O3 films was examined as a function of the oxygen concentration during deposition. While an elevated oxygen concentration yields thin films with optimal magnetic properties, slightly l…
We report a scalable approach to synthesize a large-area (up to 4 mm) thin black phosphorus (BP) film on a flexible substrate. We first deposited a red phosphorus (RP) thin-film on a flexible polyester substrate, followed by its conversion to BP in a high-pressure multi-anvil cell at room temperature. Raman spectroscopy and transmission electron microscopy measurements confirmed the formation of a nano-crystalline BP thin-film with a thickness of around 40 nm. Optical characterization indicates a bandgap of around 0.28 eV in the converted BP, similar to the bandgap measured in exfoliated thin-…
The current practice of angular (Lorentz, Polarization and absorption (LPA)) corrections in bulk materials for higher angle broad peaks, due to the Kα doublet, are based on the results of Pike (Acta Cryst., 12 (1959) 87-92) and Ladell (Acta Cryst. 14 (1961) 47-53). These results are extended to thin film x-ray diffraction. The current practice in thin film studies of using the absorption factors for monochromatic radiation in LPA corrections is incorrect in both symmetric and grazing incidence x-ray diffraction. The correct expressions for absorption corrections are developed. In addition, a n…
Thin-film based phase plates are meanwhile a widespread tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense electron-beam illumination. Recent investigations have focused on the search for alternative materials with an improved material stability. This work presents thin-film based phase plates fabricated from metallic glass alloys, which are characterized by a high electrical conductivity and an amorphous structure. Thin films of the zirconium-b…
In the present investigation resistivity Vs temperature measurements have been performed for solgel prepared pure and Ni doped CdO (NDO) thin films. The semiconducting behavior i.e. negative temperature coefficient of resistivity (TCR) of pure CdO thin film through-out the whole temperature range can be attributed mainly due to concentration dependent thermally activation mechanism of the carriers. The semiconductor to metal transition (SMT) for NDO thin films has been elucidated via combined effect of involved grain boundaries, ionic impurities, phonon scattering and carrier activation.
We report growth characteristics of epitaxial $β$-Na$_{0.6}$CoO$_{2}$ and $γ$-Na$_{0.7}$CoO$_{2}$ thin films on (001) sapphire substrates grown by pulsed-laser deposition. Reduction of deposition rate could change structure of Na$_{x}$CoO$_{2}$ thin film from $β$-phase with island growth mode to $γ$-phase with layer-by-layer growth mode. The $γ$-Na$_{0.7}$CoO$_{2}$ thin film exhibits spiral surface growth with multiterraced islands and highly crystallized texture compared to that of the $β$-Na$_{0.6}$CoO$_{2}$ thin film. This heterogeneous epitaxial film growth can give opportunity of strain e…
Epitaxial copper thin films were deposited by magnetron sputtering. The adatoms during deposition are influenced by deposition parameters which cause variations in thin film properties. XRD and FESEM studies were done to get an insight into the growth mechanisms of the films. A modeling has been done on the epitaxial thin film growth with sputtering process. The parameters during sputtering like, sputtering yield, pressure, temperature, current density, deposition time were related and an attempt has been made to analyze the sputtering process.
The electronic band structures of Bi${}_{1-x}$Sb${}_{x}$ thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi${}_{1-x}$Sb${}_{x}$ thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersi…
Poly- and single-crystal thin films of U-Mo alloys have been grown both on glass and sapphire substrates by UHV magnetron sputtering. X-ray and Electron Backscatter Diffraction data indicate that for single-crystal U1-xMox alloys, the pure cubic uranium gamma-phase exists for x > 0.22 (10 wt.% Mo). Below 10 wt.% Mo concentration, the resulting thin film alloys exhibited a mixed alpha-gamma uranium phase composition.
In the paper we consider size effects of phase transitions and polar properties of the thin antiferroelectric films. We modified phenomenological approach proposed by Kittel. The Euler-Lagrange equations were solved by direct variational method. The free energy with renormalized coefficients depending on the film thickness has been derived. The approximate analytical expression for the coefficients dependence on film thickness, temperature, polarization gradient coefficient and extrapolation lengths were obtained. We have shown how the anti-ferroelectric double hysteresis loop transforms into …
An environmentally stable mesoscopic thin film of Au of certain thickness has been deposited thermally on top of a Ag+ implanted oxide substrate to develop a close to room temperature superconductor. This thin film has been deposited in two different stages. Initially, a sol-gel derived ion conducting metal oxide (ICMO) thin film has been deposited by spin coating. Afterward, Ag+ has been introduced inside ICMO thin film by a chemical method. Following this, a thin layer of Au has been deposited on top of that Ag ion-implanted oxide via thermal evaporation. The temperature dependent resistivit…
The effects of annealing and variation of temperature on the electrical and thermoelectric properties of e-beam evaporated InSe thin films has been investigated in details. The XRD study demonstrates that the as-deposited InSe thin films are amorphous while they become polycrystalline with the presence of In3Se4 phase after annealing. The SEM micrographs reveal that the surfaces of as-deposited films are smooth whereas they become non-uniform due to annealing. The heating and cooling cycles of the as-deposited films exhibit that the resistivity of the films shows an irreversible phase-transiti…
Assembling clusters on surfaces has emerged as a novel way to grow thin films with targeted properties. In particular, it has been proposed from experimental findings that fullerenes deposited on surfaces could give rise to thin films retaining the bonding properties of the incident clusters. However the microscopic structure of such films is still unclear. By performing quantum molecular dynamics simulations, we show that C_28 fullerenes can be deposited on a surface to form a thin film of nearly defect free molecules, which act as carbon superatoms. Our findings help clarify the structure of…
Germanosilicide thin films are quite different from silicides and germanides. The germanium composition is not homogeneous, grains have a different shape, and the substrate is generally strained. This affects grain boundary grooving and favors agglomeration of germanosilicide films. Our thermodynamics model shows that the equilibrium Ge composition of germanosilicide films formed on strained substrates is inhomogeneous and these films are more likely to agglomerate than those formed on relaxed substrates, in agreement with experiments. Grain shape too can affect agglomeration: polygonal films,…
Very thin (1.2-2.5nm) self-assembled organic dielectric monolayers have been integrated into organic thin-film diode to achieve electrical characteristics. These dielectrics are fabricated by self-assembling deposition, resulting in smooth, strongly adherent, thermally stable, organosiloxane thin films having interesting electrical capacitances (around 150 nF cm-2 at -3V) and insulating properties (leakage current densities around 10-5 A cm2 at -1V).
The expression of temperature distribution along a film thickness is derived and distribution of temperature in the film as the substrate is heated is shown. The variation of film resistance with different substrate temperature is calculated and the existence of temperature gradient along the film thickness with finite thermal conductivity leads to hysteresis like behaviour on heating-cooling the film.
We present and apply a new method to measure directly weak magnetization in thin films. The polarization of a neutron beam channeling through a thin film structure is measured after exiting the structure edge as a microbeam. We have applied the method to a tri-layer thin film structure acting as a planar waveguide for polarized neutrons. The middle guiding layer is a rare earth based ferrimagnetic material TbCo5 with a low magnetization of about 20 mT. We demonstrate that the channeling method is more sensitive than the specular neutron reflection method.
Copper ferrite thin films were rf sputtered at a power of 50W. The as deposited films were annealed in air at 800°C and slow cooled. The transmission electron microscope (TEM) studies were carried out on as deposited as well as on slow cooled film. Significantly larger defect concentration, including stacking faults, was observed in 50W as deposited films than the films deposited at a higher rf power of 200W. The film annealed at 800°C and then slow cooled showed an unusual grain growth upto 180nm for a film thickness of ~240nm. These grains showed Kikuchi pattern.
Neodymium is a remarkable active component in numerous magnetic alloys that are used in various applications. However, the application of bare neodymium thin film is limited due to the lack of information about its electrical and magnetic properties. We report synergistic study of Nd thin film using experimental and theoretical techniques of polarized neutron reflectometry, magnetoresistance measurement and density functional theory. Unlike bulk Nd, thin film specimen is a very poor electrical conductor. Also, as grown thin film on silicon substrate does not exhibit any magnetism in zero field…
To engineer strain relaxation of sputtered BST thin films on Pt-Si wafers, homo-buffer layer method was applied to eliminate Pt hillock formation. Thin BST homo-buffer layers were deposited at room temperature and subsequently the main BST layer was deposited at 650°C, Pt hillock free BST films were obtained with homo-buffer thickness above 5 nm. Relatively good electrical properties were obtained for BST thin films with 15 and 25 nm homo-buffer layer (T= 30 % at 5V and tan δ= 0.018).
The tribological properties of two smooth surfaces in the presence of a thin confined film are investigated with a generic model for the interaction between two surfaces and with computer simulations. It is shown that at large normal contact pressures, an ultra thin film automatically leads to static friction between two flat surfaces - even if the surfaces are incommensurate. Commensurability is nevertheless the key quantity to understand the tribological behavior of the contact. Qualitative differences between commensurate and incommensurate contacts remain even in the presence of a thin fil…
Oblique angle deposited oxide thin films have opened up new dimensions in fabricating optical interference devices with tailored refractive index profile along thickness by tuning its microstructure by varying angle of deposition. Microstructure of thin films strongly affects surface morphology as well as optical properties. Since surface morphology plays an important role for the qualification of thin film devices for optical or other applications, it is important to investigate morphological properties. In present work, HfO2 thin films have been deposited at several oblique angles. Morpholog…
Tin doped indium oxide (ITO) thin films are being used extensively as transparent conductors in several applications. In the present communication, we report the electrical transport in DC magnetron sputtered ITO thin films in low temperatures (25-300 K). The low temperature Hall effect and resistivity measurements reveal that the ITO thin films are moderately dis-ordered (kfl~1) and degenerate semiconductor. The transport of charge carriers in these disordered ITO thin films takes place via the de-localized states. The disorder effects lead to the well- known metal-insulator transition; this …
A phenomenological theory of the incommensurate phase transition in thin films is presented for the case of the single-component order parameter. The order parameter distribution over the film is obtained under the assumption of slowly-varying amplitude. The size effect on the temperature of the phase transition into the incommensurate phase has been considered.
The influence of La and Nd co-substitution on the structural and magnetic properties of BiFeO3 (BFO) thin films was examined. Epitaxial thin films of pure and, La and Nd co-doped BFO on the SrRuO3 buffered single crystal SrTiO3 (001) substrate were deposited using pulsed laser deposition. The structural change in co doped La and Nd BFO thin films which was caused by the changes of force constant in the crystal lattice induced by ionic radii mismatch was investigated. Raman spectroscopy studies manifest the structural change in doped BFO films from rhombohedral to monoclinic distorted phase whi…
Thin film growth of ferroelectric or multiferroic materials on SrTiO3(111) with a buffer electrode has been hampered by the difficulty of growing flat electrodes on this polar orientation. We report on the growth and characterization of SrRuO3 thin films deposited by pulsed laser deposition on SrTiO3(111). We show that our SrRuO3(111) films are epitaxial and display magnetic bulk-like properties. Films presenting a thickness between 20 and 30nm are found to be very flat (with an RMS of about 0.5 nm) and therefore suitable as bottom electrodes in heterostructures.
Tin sulphide thin films of p-type conductivity were grown on glass substrates. The refractive index of the as grown films, calculated using both Transmission and ellipsometry data were found to follow the Sellmeier dispersion model. The improvement in the dispersion data obtained using ellipsometry was validated by Wemple-Dedomenico (WDD) single oscillator model fitting. The optical properties of the films were found to be closely related to the structural properties of the films. The band-gap, its spread and appearance of defect levels within the band-gap intimately controls the refractive in…
I present here theory of PZT thin film - MgO substrate system thermal expansion effect. I show that elastic properties of the substrate have to be taken into account to describe this effect.
Thin films of Pr0.7Ca 0.3MnO3, Nd-0.5Ca0.5MnO3 and Nd0.5Sr0.5MnO3 have been fabricated. by pulse laser deposition. Magnetic and electrical transport properties of these films were compared with their bulk solids. All the films grow in (101) direction on LaAlO3(100). Electrical transport measurements carried out with and without magnetic field has shown dr/dT<0 in these thin films. Application of magnetic field has shown dilution of the insulating behavior. The magnetization studies of Nd-0.5Sr0.5MnO3 exhibited ferromagnetic behavior at 260K and showed antiferomagnetic feature below 130K. This …
Based on Landau-Devonshire (LD) phenomenological theory, phase diagram of epitaxial BST50/50 thin films on anisotropic in-plane strains is investigated. Different from BaTiO3 thin films, the paraelectric phase appears under the anisotropic misfit strains on BST50/50 thin films at the room temperature. The pyroelectric property of the BST films is also calculated, we find that the position of pyroelectric peak greatly depends on anisotropic misfit strains. Keywords: anisotropic in-plane strains; BST thin films; phase diagram
We report measurements of viscoelastic properties of thin polymer films of 10-100 nm at the MHz range. These thin films are confined between a quartz crystal resonator and a millimetric bead layer, producing an increase of both resonance frequency and dissipation of the quartz resonator. The shear modulus and dynamic viscosity of thin films extracted from these measurements are consistent with the bulk values of the polymer. This modified quartz resonator provides an easily realizable and effective tool for probing the rheological properties of thin films at ambient environment.
We have investigated the electronic properties of epitaxial orthorhombic SrIrO3 thin-films under compressive strain. The metastable, orthorhombic SrIrO3 thin-films are synthesized on various substrates using an epi-stabilization technique. We have observed that as in-plane lattice compression is increased, the dc-resistivity (\r{ho}) of the thin films increases by a few orders of magnitude, and the d\r{ho}/dT changes from positive to negative values. However, optical absorption spectra show Drude-like, metallic responses without an optical gap opening for all compressively-strained thin films.…
Herein, titania thin films are fabricated by a facile liquid-phase method based on vacuum filtration of a colloidal suspension of titania nanosheets, which is followed by thermal annealing to transform the nanosheet film into anatase TiO2. Nanosheet-derived titania thin films exhibit poor resistive switching with an interface-type mechanism. This behaviour is distinct from the filamentary switching that has been observed with titania thin films fabricated by other conventional techniques. This tolerance against conducting-filament formation may be ascribed to a low concentration of oxygen vaca…
