Annealing Of Films Research Articles

Solvent Vapor Annealing of a Diblock Copolymer Thin Film with a Nonselective and a Selective Solvent: Importance of Pathway for the Morphological Changes.

Diblock copolymer thin films of polystyrene-block-poly(dimethyl siloxane) (PS-b-PDMS) featuring PDMS cylinders in a PS matrix are investigated during solvent vapor annealing with mixtures of n-heptane (which is strongly selective for PDMS) and toluene (which is close to nonselective for both blocks). Swelling in the vapor of one of the pure solvents and exchanging it stepwise by the vapor of the other solvent is compared to swelling in a given binary solvent vapor mixture for a prolonged time. The resulting structural changes, such as ordering of the cylinders on a hexagonal lattice and their transition into lamellae, are followed using in situ, real-time grazing-incidence small-angle X-ray scattering (GISAXS). In three runs, the sequence of solvent vapor swelling and vapor exchange is varied. Compiling the resulting morphologies in a diagram of states in dependence on the solvent content in the film and in the minority nanodomains allows insight into the role of the glass transition of the PS matrix for the ordering processes and their time scales. Based on these findings, a protocol is suggested to efficiently obtain an order-to-order transition from the cylindrical morphology with random domain orientation to the oriented lamellar state.

Hot-injection synthesis of ultrasmall CuIn3Se5 quantum dots and production of ink-coated films

For the first time, we synthesized ultrasmall colloidal CuIn3Se5 quantum dots (QDs) with an average diameter of 3.5 nm and they were used to obtain nearly continuous ink-coated films by the hot-injection method. Copper chloride, indium chloride, and selenium were used as reagents in oleylamine as the solvent to synthesize CuIn3Se5 QDs without other organometallic precursors. The synthesized CuIn3Se5 QDs had a cubic crystal structure and they exhibited a strong quantum confinement effect according to their optical absorption spectra. The as-deposited and annealed thin films prepared from an ink solution containing these QDs exhibited p-type characteristics, a high band gap, and low surface roughness. The optical constants were determined by interference-free mathematical modeling for the as-deposited and annealed films obtained with the synthesized CuIn3Se5 QDs. Moreover, under 1 sun of simulated radiation, the photocurrent was greatly enhanced (>1000%) for the annealed CuIn3Se5 QD film compared with the as-deposited film. These results suggest that colloidal CuIn3Se5 QD films could potentially be used as an active layer in low-cost highly efficient Cu(In,Ga)Se/CdS thin film solar cells.

Influence of substrate (Si and glass), Cu under-layer, in situ annealing of Ta/Cu and post-annealing on magnetic properties of [Co(0.3 nm)/Ni(0.6 nm)]4, 10 multilayer thin films

Thin films of [Co(0.3 nm)/Ni(0.6 nm)]4, 10 multilayers (MLs) stack were deposited on Si and glass substrates using DC magnetron sputtering. The magnetic stack layers were deposited under various conditions such as (i) without using any under layer (referred as-prepared film) (ii) with Cu under-layer (iii) with in situ annealing of Ta/Cu under-layer (iv) with in situ along with post annealing of overall magnetic stack. The as prepared [Co(0.3 nm)/Ni(0.6 nm)]4 films deposited on Si as well as on glass substrate exhibit perpendicular magnetic anisotropy (PMA) as per magnetization measurements at room temperature. Inserting Cu under layer to this magnetic stack helps to enhance the coercivity (HC), saturation magnetization (MS) and the squareness [MR/MS] of the films in comparison to as-prepared MLs. Thin films of MLs with in-situ annealing of Ta/Cu, further enhance the value of MS and Sq in comparison to as-prepared and with Cu-under layer MLs. Even though the HC, MS and squareness [MR/MS] of M-H loop of post annealed films are comparable to the films prepared under other three conditions, the PMA was observed only in the latter case. Additionally, on increasing the number of magnetic bi-layers of the stack from 4 to 10 i.e. [Co (0.3 nm)/Ni (0.6 nm)]10, it is observed that the magnetic property parameters such as HC, MS and Sq were enhanced along-with exhibiting perpendicular magnetic anisotropy (PMA). The observation of PMA in these films may be due to the growth of Cu along (111) direction and Co/Ni (111) crystalline orientation, as demonstrated by XRD pattern and the topography analyses by AFM.

Low annealing temperature effect on Structural, and optical properties of CuO nanostructure thin films

In present work, the modified chemical bath deposition method (CBD) called successive ionic layer adsorption and reaction effective coast method was used for deposited copper oxide CuO nanostructured thin films. Structural, surface texture and optical characteristics of the deposited films were studied as a function of low annealing temperature (150, 200 and 250) °C. X-ray diffraction studies showed that the as-deposited and annealed films exhibited low crystallinity of polycrystalline nature in the monoclinic phase. It is observed a fixed or very little increment of peaks intensity and the crystallinity of the deposited films with the increase of annealing temperature to 250 °C. The lattice constants were calculated and show good agreement with the standard values. The crystallite size was decreased, whereas the dislocation density and the number of crystallites were increased with the increment of annealing temperature. The average grain diameter was increased and the average surface roughness decreased with the increment of annealing temperature. The optical energy gap for the as-deposited film is 1.87eV and increased to (2.03, 2.06 and 2.09) eV with the increment of annealing temperatures. The Urbach tails energy width decreased from 0.91 eV to (0.73, 0.54 and 0.46) eV for as-deposited and annealed films at low temperatures (150, 200 and 250) °C respectively. The low annealing temperatures was used because the deposition process was performs at low temperatures below 100 °C, therefore_it can be concluded that the low annealing temperatures used in this work are not suitable temperatures for the growth of CuO films and it can be above 300 °C to enhance the film crystallinity and formation of CuO phase.

Effects of Oxygen Adsorption on Morphological Evolution of Epitaxial Ag Island Films Grown on Si

This study presents results showing that oxygen adsorption can significantly affect the morphological evolution of silver island films epitaxially grown on Si(100) and Si(111) substrates. The effects of oxygen adsorption are characterized by analyzing the morphologies formed during the thermal annealing of the island films under different annealing gas compositions. Silver island films are shown to evolve into an isotropic spherical shape in the presence of oxygen, suggesting that oxygen adsorption decreases the surface energy anisotropy of silver, which is supported by our density function theory calculation results. Oxygen is also observed to enhance the rate of dewetting and coarsening of the films, leading to a smaller areal coverage and smaller number density of silver particles. This is explained by the decrease in the activation barrier for the surface diffusion of silver adatoms and their clusters on silver and silicon surfaces with chemisorbed oxygen.

Formation of a Two-Phase Structure in CH3NH3PbI3 Organometallic Perovskite

The effect of annealing of a CH3NH3PbI3 organometallic perovskite film on its electrical, photoelectrical, and optical properties is studied. It is shown that annealing at the temperature Ta > 140°C results in the formation of a two-phase structure consisting of perovskite and lead iodide, whose relative content depends on the conditions of annealing, specifically, on the annealing temperature. The formation of PbI2 in the perovskite structure yields a decrease in the conductivity and photoconductivity of the material. The studies suggest the possibility of the formation of planar structures composed of semiconductor materials with different band gaps, 1.6 eV (CH3NH3PbI3) and 2.4 eV (PbI2).

The effect of annealing temperature thin films indium doped SnO2 to optics properties and material composition

This study aims to analyze the effect of annealing of tin oxide thin film doped with Indium. SnO2 thin film has many benefits as electronic devices, solar cells, LPG sensors, etc. Preparation of SnO2: In a thin film using a sol-gel spin coating technique that produces a thin film of high quality. The transmittance of the thin film experienced decreases with increasing ripening temperature with the transmittance of 96.6, 94.7, 89.6, 87.1, and 78.2% at a wavelength of 350 nm with annealing temperature increase, respectively. Thin-film absorbance has increased with higher heating temperatures i.e 3.01, 3.34, 3.41, 3.62, and 3.77, respectively. SnO2 thin film gap energy: In decreases due to increased ripening temperature at room temperature (35), 50, 100, 150, and 200 °C ie 3.65, 3.61, 3.59, 3.58, and 3.56 eV for direct energy gap and 3.96, 3.94, 3.93, 3.91, and 3.89 eV for indirect energy gap, respectively. The decreasing value of the gap energy makes the SnO2: In thin-film material faster in carrying current. The activation energy are decreased by increasing annealing temperature with value 2.91, 2.73, 2.15, 2.11 and 2.09 eV, respectively for increase temperature which makes electrons flow faster. Furthermore, thin-films composition with mass percentage Sn are 16.97% with atomic 2.77% and In are 1.46% with atomic 0.25%.

Nanocone Structures Enhancing Nitrogen-Vacancy Center Emissions in Diamonds

In this study, nitrogen-vacancy center emissions from nanocone structures fabricated on diamond surfaces by gold film annealing and inductively coupled plasma etching techniques were characterized. First, the diamond substate deposited with gold film was annealed to form a nano-sized dot mask. Second, through inductively coupled plasma etching, nanocone-shaped structures were fabricated using optimized gold dots as masks. Finally, the as-fabricated nanocone and planar structures were investigated with photoluminescence experiments at temperatures ranging from room temperature to 80 K, with the results showing approximately two-fold higher emission values for nitrogen-vacancy centers from nanocones.

Application of ZrB2 thin film as a low emissivity film at high temperature

Zirconium diboride exhibits high thermal conductivities and high melting point, which are beneficial for use in extreme environments. Examples including cutting tools, high-temperature electrodes and leading edges of hypersonic space vehicles. However, there is limited literature on the infrared properties of ZrB2 thin films. In this study, we report the results of infrared emissivity of sputter-deposited films and post-annealed films. X-ray diffraction shows promoted crystalline quality and grains growth for ZrB2 films with the increasing annealing temperature and time. The thin film exhibits high thermal stability and a low infrared emissivity of 0.01 (8 ~ 14 μm) after annealed at 1000℃ for 10 h. Besides, with an increase in annealing temperature and annealing time, film densification and grains growth were observed, leading to decrease of electrical resistivity and infrared emissivity.

Improving optical properties and controlling defect-bound states in ZnMgO thin films through ultraviolet–ozone annealing

Bandgap-engineered oxide semiconductors have received widespread research attention in such applications as sensors, photodetectors, electronic devices, and solar cells. Zinc magnesium oxide (ZnMgO) is important in optoelectronics because of its wide bandgap and high excitonic binding energy. A primary drawback of ZnMgO thin films has been the presence of inherent point defects, which limits their applicability in optoelectronics devices; nevertheless, these defects can be overcome through post-growth annealing. However, annealing temperatures are typically high, in the range of 700-1000°C, which is unfit for integration in upcoming flexible electronic device applications. Herein, we propose an ultraviolet-ozone (UVO) annealing technique to improve the quality of thin films; the proposed approach is a low-temperature, simple, and cost-effective process. We studied the effects of postgrowth UVO annealing time (10, 30, 70, and 90 min) on radio frequency sputtered ZnMgO thin films. The films were then characterized through optical, structural, and elemental characterization techniques. Post-UVO annealing considerably improved near band emissions and suppressed defect bound emission. Room-temperature photoluminescence measurements revealed a 104 improvement in the near band emission peak of the 70 min UVO treated film compared with the as-deposited film. The ratio of the peak intensities of near band emission and defects band emission for the 70-min post-UVO film was 50 × higher than that of the as-deposited film. High-resolution X-ray photoelectron spectroscopy evidenced the suppression of oxygen vacancies and strengthening of the metal–oxygen bonds in the ZnMgO lattice of the 70-min post-UVO annealed film. Scanning electron microscopy images demonstrated improvements in the morphological properties of the post-UVO films.

Post-deposition annealed MoO3 film based high performance MSM UV photodetector fabricated on Si (100)

Molybdenum oxide (MoO3) films were prepared on Si (100) at room temperature using radiofrequency (RF) magnetron sputtering technique. The films were annealed in the presence of air at different temperatures from 100 to 550 °C. The as-prepared films were amorphous as revealed by the X-ray diffraction analysis. Post-deposition annealing of MoO3 film enhanced its crystalline structure, showing β-MoO3 phase at 100 °C and a mixture of α-MoO3 and β-MoO3 phases at 300 °C. The crystallinity of α-MoO3 improved with increasing the annealing temperature to 500 °C, however, the β-MoO3 phase became amorphous. The film was dissolved at 550 °C as no diffraction peak of MoO3 was detected at this temperature. The band gap of MoO3 was evaluated through ultraviolet–visible spectroscopy. The results showed a decrease in the band gap from 3.70 to 3.39 eV with increasing the annealing temperature to 500 °C. The film with optimum crystalline quality was used to fabricate a metal-semiconductor-metal (MSM) photodetector device. The photo-detection characteristics of the film were studied after the deposition of Nickel contacts on MoO3 using a metal mask having interdigitated electrodes. The fabricated device exhibited a high current gain and sensitivity under 365 nm UV illumination. The responsivity of the device under UV light was 0.41 A/W at 7 V. The rise and decay time of UV photodetector were 0.32 and 0.23 s respectively. These findings suggested that the MoO3 film with dominant orthorhombic α-phase can potentially be used for the photodetector application.

Structure evolution during deposition and thermal annealing of amorphous carbon ultrathin films investigated by molecular dynamics simulations

The evolution of the structure of amorphous carbon (a-C) films during deposition and thermal annealing is of significant interest from both the materials science and application perspectives. However, despite the voluminous literature of studies dealing with the deposition and physical properties of a-C films, basic understanding of the structure evolution due to phase change during film growth and heating is fairly sparse and empirical, presumably due to the lack of high-resolution instruments that can probe structural changes at the atomic and molecular levels in real time. Molecular dynamics (MD) is a powerful computational method for studying atomic/molecular-scale movement and interactions. Thus, the objective of this study was to perform MD simulations that provide insight into changes in the structure of ultrathin a-C films during deposition and annealing. Simulation results reveal a multi-layer film structure, even for a-C films as thin as ~20 Å, the existence of a deposition energy that yields a-C films with the highest sp3 content, the transient and steady-state stages of the structure evolution during annealing at different temperatures, and the changes in the hybridization state (mainly in the bulk layer) encountered during annealing at elevated temperatures. The MD results of this study are of particular importance to applications where the deposition conditions and operation temperature affect the structure and, in turn, the physical properties of ultrathin a-C films used as protective overcoats.

Preparation and characterization of layer-diffusion processed InBi2Se4 thin films for photovoltaics application

In this research work, optoelectronic properties of Indium bismuth selenide (InBi2Se4) thin films are studied for their potentials for photovoltaic applications. The InBi2Se4 films are prepared via a thermal co-evaporation technique on glass substrate using Bi2S3 powders and indium granules. The as-deposited films are then annealed at different temperatures to convert into InBi2Se4 thin films. Results show that the obtained InBi2Se4 films possess excellent optoelectronic properties as an optimum bandgap of 1.2 eV was obtained for the film annealed at 350 °C. Based on characterization results of current and voltage realiationships, both as-deposited and annealed InBi2Se4 thin films show a linear relationship between current and annealing temperature. It was also noted that with increasing grain-size of the film, the current is also increased at a fixed applied voltage.

Structural and mechanism study on enhanced thermal stability of hydrogenated diamond-like carbon films doped with Si/O

a-C:H and a-C:H:Si:O films with two different Si/O co-doping contents had been deposited using a PECVD system by the mixture of C2H2 and HMDSO gas. The structure evolution of as-deposited and annealed films had been characterized by the Raman spectroscopy, XPS and FTIR. A progressive increase of sp2 carbon sites and a reduction of sp3 with the increase of the annealing temperature were expected. However, the Si/O co-doping was found to be able to reduce the graphitization degree of the annealed films. After annealing at 400 °C, the decrease rate of sp3 fraction of a-C:H film was 14.2%, while the a-C:H:Si:O (0.93 at.% Si) film was 8.16% and the a-C:H:Si:O (3.62 at.% Si) film was 6.8%. To understand the mechanism on the improved thermal stability by Si/O co-doping, the structure and residual stress of the a-C:H and a-C:H:Si:O films were analyzed. The results revealed that silicon atoms were incorporated into the carbon network by substituting carbon atoms of the films, which had also been characterized contributed to produce the CSi sp3 bonds stabilized by the oxygen. Residual stress characterization also demonstrated that, the residual stress of the a-C:H:Si:O films was greatly reduced compared with that of the a-C:H films. Therefore, the fraction of the highly strained CC sp3 bonds, which were more likely to break at elevated temperature, was reduced in the a-C:H:Si:O films. This kind of structure evolution endowed the a-C:H:Si:O films higher hardness and adhesion at high temperature.

ITO and electron transport layer-free planar perovskite solar cells on transparent Nb-doped anatase TiO2-x electrodes

Here, we reported on planar perovskite solar cells (PSCs) which are free of the indium tin oxide (ITO) and electron transport layer (ETL) directly prepared on Nb-doped TiO2-x (NTO) electrodes. By rapid thermal annealing of NTO film at a temperature of 600 °C under vacuum ambient, we obtained conductive anatase NTO electrodes that act as transparent electrodes and ETL simultaneously in ITO and ETL-free PSCs. The sputtered NTO electrode showed decreasing resistivity with decreasing temperature, indicating metallic conductivity. A planar NTO∖(FAPbI3)1-x(MAPbBr3)x∖Spiro-MeOTAD∖Au cell showed a power conversion efficiency of 12.50% and open-circuit voltage of 1.08 V in spite of the absence of ETL. The ITO and ETL-free PSC with an NTO electrode exhibited a higher open-circuit voltage of 1.08 V than did an ETL-free PSC with ITO electrode because of effective hole blocking by the NTO electrodes. Our results suggest that sputtered NTO film is a promising multi-functional electrode acting as ETL and transparent electrode simultaneously for achieving simply fabricated and cost-effective PSCs.

Evolution of TiOx-SiOx nano-composite during annealing of ultrathin titanium oxide films on Si substrate

This paper discusses the formation of the TiOx-SiOx nano-composite phase during annealing of ultrathin titanium oxide films (~27 nm). The amorphous titanium oxide films are deposited on silicon substrates by sputtering. These films are important for high-k dielectrics and sensing applications. Annealing of these films at 750 °C in the O2 environment (for 15–60 min) resulted in the polycrystalline rutile phase. The films exhibit Raman peaks at 150 cm−1 (B1g), 435 cm−1 (Eg), and 615 cm−1 (A1g) confirming the rutile phase. The signature TO (1078 cm−1) and LO (1259 cm−1) infrared active vibrational modes of Si–O–Si bond confirms the presence of silicon-oxide. The X-ray photoelectron spectra of the TiOx films show multiple peaks corresponding to Ti metal (453.8 eV); Ti4+ state (458.3 eV (Ti 2p3/2) and 464 eV (Ti 2p1/2)); and Ti3+ state (456.4 eV (Ti 2p3/2) and 460.8 eV (Ti 2p1/2)). The O1s XPS spectra peaks at 530–533 eV can be attributed to Ti–O and Si–O bonds of the TiOx-SiOx nano-composite phase in the annealed films. The depth profiling XPS study shows that the top surface of the annealed film is mainly TiOx and the amount of SiOx increases with the depth.

The Influence of Film Thickness on the Annealing-Induced Changes of Texture and of the Fraction of Crystalline Phase in Pt Films

Textured Pt films 20–80 nm in thickness magnetron-sputtered on an oxidized c-Si(100) substrate have been annealed in vacuum at 500°C for 60 min. The texture parameters and the fraction of crystalline phase as a function of thickness have been studied for as-prepared and annealed films using methods of X-ray diffraction analysis. The fraction of crystalline phase in textured films has been determined by a special technique based on rocking curve examination. It has been found that for all as-deposited films, annealing improves texture and increases the fraction of crystalline phase, the thinner the film, the greater the effect. This result is explained by the appearance of large secondary grains, the volume fraction of which grows with decreasing thickness. The nonuniform in-depth distribution of texture parameters and fraction of crystalline phase in as-grown Pt films has been studied.

RESISTIVITY-TEMPERATURE DEPENDENCE, THERMAL AND ELECTRICAL PARAMETERS OF Se65-xAs35Sbx THIN FILMS: (1µm, 5 K.min-1 )

Sheet resistance, Rs , measurements for the (Se65-xAs35Sbx thin films with (0 ≤ x ≥ 10) at. %) with thickness film 1000 nm and heating rate, 5 K/min has been explained in this work. Measurements of the sheet resistance used to compute the thermal and electrical parameters in the temperature range from 300 to 665 K. In the sheet resistance curves, two main regions have been considered clearly evidence of one crystallization region for the studied films. The activation energy, Ec , of crystallization and Avrami index, n, were estimated. The change of activation energy with volume of crystalline fraction has been deduced. The electrical results of the studied films appear two types of conduction channels which contribute two conduction mechanisms in crystallized region. The activation energies ΔE, two pre-exponential factors 0  , *  0 and other parameters has been computed in both of the extended and hopping states regions. The crystalline phases for the as-deposited and annealed films were identified using by x-ray diffraction (XRD).

Advantages of drawing and rolling metals with pulse current

The results of studies on the drawing of copper and steel wires using pulsed current in the deformation zone are presented. The analysis of their structure and physicomechanical properties is given. As a result, the drawing forces of copper and steel wires are reduced by 30-35%, the electrical resistance is reduced by 18-20%, a more perfect axial texture appears, the ductility of the wires increases compared to warm drawing. In the steel wire, the α-phase content sharply decreases, which is predominantly released in the surface layer by several microns. We propose methods for the modernization of rolling equipment for technology using pulsed current. The efficiency of using a high-density pulsed current on a rolling mill for producing stainless steel from an initial billet of 2 mm thick and 100 mm wide 0.3 mm thick tape without intermediate annealing and oxide film is shown.

The effects of post heat treatment on ITO/AgAl/ITO/p-Si multilayer films

For the past few decades, the quest for an improve indium tin oxide (ITO) films have attracted a lot of interest by scientists and industries for application in advanced optoelectronic devices. ITO/AgAl/ITO multilayer films were deposited on p-silicon (Si) substrates at room temperature by radio frequency (RF) and direct current (DC) magnetron sputtering respectively. The effects of post-heat (annealing) treatment on the structural, optical and electrical properties of the ITO/AgAl/ITO multilayer films were investigated at different temperature of 200 °C, 300 °C, 400 °C and 500 °C respectively. X-ray diffraction (XRD) results reveal an amorphous structure for the as-deposited film whereas the post annealed films show a polycrystalline and cubic bixbyite structure with preferential peaks orientation along ITO (222), Ag (111), and ITO (440) crystalline directions. Atomic force microscopy (AFM) analysis indicates a smoother surface morphology and improved grain size after post heat treatment. Ultraviolet-visible spectrophotometer measurements show a significant increase in optical transmittance spectra as the annealing temperature increases. Maximum transmittance peak of 87.2 % was obtained by film annealed at 500 °C. Four-point probe measurements exhibit a substantial decrease in sheet resistance with respect to increasing post-annealing temperature. The sheet resistance of the as-deposited film is about 7.85 Ω/sq and falls down to 3.23 Ω/sq as the post-heat temperature is increased to 500 °C. Compared to as-deposited film, the post annealed multilayer films optical and electrical properties have been successfully enhanced, fine turned and favourable for Si solar cell application.