Annealing Of Films Research Articles

Growth of Ge clathrate on sapphire and optical properties

Type II Ge clathrate (NaxGe136) films containing a small amount of Na were successfully synthesized on a sapphire substrate by thermal annealing of precursor NaGe composite films. A new technique for Na removal from NaxGe136 was developed by applying the electric field in an Ar environment at 275 °C. Rietveld refinement analysis of NaxGe136 films showed an almost guest free nature (Na contents x ∼ 0) using this new technique. In addition, absorbance spectra obtained from NaxGe136 films showed a decrease in the absorbance intensity in the lower photon energy (<0.5 eV) with annealing. It suggests the decrease in free carrier absorption by the removal of Na atoms in NaxGe136.

A Polymerization-Assisted Grain Growth Strategy for Efficient and Stable Perovskite Solar Cells.

Intrinsically, detrimental defects accumulating at the surface and grain boundaries limit both the performance and stability of perovskite solar cells. Small molecules and bulkier polymers with functional groups are utilized to passivate these ionic defects but usually suffer from volatility and precipitation issues, respectively. Here, starting from the addition of small monomers in the PbI2 precursor, a polymerization-assisted grain growth strategy is introduced in the sequential deposition method. With a polymerization process triggered during the PbI2 film annealing, the bulkier polymers formed will be adhered to the grain boundaries, retaining the previously established interactions with PbI2 . After perovskite formation, the polymers anchored on the boundaries can effectively passivate undercoordinated lead ions and reduce the defect density. As a result, a champion power conversion efficiency (PCE) of 23.0% is obtained, together with a prolonged lifetime where 85.7% and 91.8% of the initial PCE remain after 504 h continuous illumination and 2208 h shelf storage, respectively.

High-temperature X-ray scattering studies of atomic layer deposited IrO2

IrO2 is an important material in numerous applications ranging from catalysis to the microelectronics industry, but despite this its behaviour upon annealing under different conditions has not yet been thoroughly studied. This work provides a detailed investigation of the annealing of IrO2 thin films using in situ high-temperature X-ray diffraction and X-ray reflectivity (HTXRR) measurements from room temperature up to 1000°C in oxygen, nitrogen, forming gas and vacuum. Complementary ex situ scanning electron microscopy and atomic force microscopy measurements were conducted. The combined data show the dependencies of crystalline properties and surface morphology on the annealing temperature and atmosphere. The reduction of IrO2 to Ir takes place at a temperature as low as 150°C in forming gas, but in oxygen IrO2 is stable up to 800°C and evaporates as a volatile oxide at higher temperatures. The IrO2 crystallite size remains constant in oxygen up to 400°C and increases above that, while in the more reducing atmospheres the Ir crystallites grow continuously above the phase-change temperature. The role of HTXRR in the analysis is shown to be important since its high sensitivity allows one to observe changes taking place in the film at temperatures much below the phase change.

Effect of annealing on structural, morphological and optical properties of CdTe/(Cd-Zn)S thin films

Here, we present the results of an investigation on structural, morphological and optical properties of CdTe/(Cd-Zn)S films deposited on FTO substrate through electrodeposition technique for solar cell application. The deposited films were heat-treated in the presence of CdCl2 for the recrystallization. Various techniques, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), optical studies (absorption, transmission, band-gap and photoluminescence studies) were employed to examine the structural, morphological and optical properties. XRD spectra show the preferential orientation (111) in CdTe films. Uniform and bounded grains are observed upon annealing of the films. The changes in CdTe film were attributed to nucleation of the CdTe grains during the CdCl2 treatment. The band-gap (Eg) value for CdTe estimated from absorption spectra and corresponding Tauc’s plots comes to be ~1.50eV. Summary of results suggests that the annealing of different component films is helpful in improving solar cell performance.

Kinetic Model of Structural Relaxation in Diblock Copolymer Film

A relaxation model for the structure ripening under annealing of a microphase-separated polymer film has been developed. Equations have been derived that describe the appearance and annihilation of defects in the kinetically controlled mode based on the experimental data on the hexagonal structure evolution. Using that equations, the time dependences of the defect-free area size have been analyzed. It has been found that the predominance of the defect annihilation upon their triple contact leads to the power-law dependence of the orientation correlation length ξor ~ t1/4, which is observed experimentally at high annealing temperatures. A more detailed analysis of the evolution of two types of defects (dislocations and disclinations) shows that this dependence can also be realized in a model that takes into account the annihilation of disclination pairs and quadruples providing that dislocations influence this process. The results demonstrate that macrokinetic models can describe structural rearrangements in block copolymer films.

Effect of thermal oxidation on the optical, electrical, and chemical properties of zinc nitride films grown by reactive magnetron sputtering

We have studied the effect of post growth annealing in oxygen ambient on the optical, chemical and electronic properties of zinc nitride thin films. The films were prepared by reactive radio frequency magnetron sputtering of zinc target in the presence of argon and nitrogen gasses at a substrate temperature of 300 °C. Post growth annealing was performed at annealing temperatures of 300, 400, 500, 600, and 700 °C in the oxygen environment to transform the zinc nitride films into p-type zinc oxide. Atomic force microscopy of the films reveal that surface roughness and grain size of the films are directly proportional to the post-growth annealing temperature. X-ray photoelectron spectroscopy of the films revealed that as-grown film has the highest intensity of nitrogen in the film whereas little nitrogen remains in the films that were annealed at 500 °C and higher temperatures. Films annealed at higher temperatures have lower carrier concentration but higher Hall mobility compared to the as-grown film and the films annealed at lower temperature. Moreover, as-grown film and the films annealed at lower temperature have n-type conductivity whereas films annealed at temperatures above 500 °C exhibit p-type conductivity. Films annealed at lower temperature have bandgap values closer to the zinc oxynitride but bandgap of the films annealed at higher temperatures have values close to the bandgap of zinc oxide. This indicates that post growth annealing of zinc nitride films at 500 °C in oxygen ambient transforms it into p-type zinc oxide.

Growth of visible-light-responsive ferroelectric SbSI thin films by molecular beam epitaxy

Photoresponsive ferroelectrics are recently under intense study due to their potential application to photovoltaic devices. Antimony sulfoiodide (SbSI) is a prototypical compound that possesses both ferroelectricity and a strong visible-light-response. However, most of the SbSI films reported so far have a polycrystalline structure with a randomly oriented polarization axis. In this study, we have fabricated c-axis textured SbSI thin films through annealing of amorphous films deposited in a molecular beam epitaxy system, employing Sb2S3 and SbI3 sources. The fabricated films are highly uniform and have the polarization axis ordered vertical to the film plane. We have confirmed that the films show a strong visible-light-response and ferroelectricity in accord with bulk samples. These results will stimulate the development of photovoltaics employing narrow bandgap ferroelectric compounds.

Investigation of the Effect of Thermal Annealing on the Electrical Properties of the Near-Surface Layer of MBE n-HgCdTe Using MIS Techniques

Heteroepitaxial n-Hg0.78Cd0.22Te films with near-surface graded-gap layers were grown by molecular beam epitaxy and subjected to two-stage thermal annealing in saturated mercury vapor atmosphere. The first stage of annealing was carried out for 2 h at a temperature of 360°C. The second stage was carried out at a temperature of 220°C for 24 h. Similar annealing was carried out after As+ ion implantation to activate the introduced impurity and anneal radiation defects. Based on as-grown and annealed films, metal–insulator–semiconductor (MIS) structures were formed by depositing an Al2O3 dielectric by plasma atomic layer deposition. The admittance of fabricated MIS structures was studied in a wide range of frequencies and temperatures. It was found that after thermal annealing, the properties of the n-HgCdTe surface layer are noticeably changed, which is manifested as a decrease in the density of slow states in the transition layer between the dielectric and the semiconductor, and an increase in the generation of minority charge carriers in the n-HgCdTe near-surface layer. These changes in the properties of n-HgCdTe after thermal annealing are associated with the modification of the defect system of the near-surface layer of the semiconductor and the transition layer between dielectric and semiconductor. No significant changes were detected in the bulk properties of the epitaxial film after thermal annealing. A decrease in the density of states near the interface between HgCdTe and Al2O3 during thermal annealing makes it possible to facilitate the electrical characterization of MIS structures by suppressing hysteresis phenomena.

Tin antimony sulfide (Sn6Sb10S21) thin films by heating chemically deposited Sb2S3/SnS layers: Studies on the structure and their optoelectronic properties

Tin antimony sulfide thin films (Sn6Sb10S21) were obtained on glass substrates by heating chemical bath deposited Sb2S3/SnS layers. The report primarily focuses on the structure, composition, morphology, optical and electrical properties of the thin films formed at the temperature range of 300–450 °C for 30 min as well as at the optimized temperature of 390 °C for 1, 2 and 3 h in low vacuum. X-ray diffraction and Raman analysis revealed the crystallization of ternary phase Sn6Sb10S21 at temperatures higher than 390 °C. X-ray photoelectron study identified the presence of Sn2+, Sb3+ and S2- states in the ternary phase and the depth profile analysis exhibited a uniform distribution of elements throughout the thickness. Further, surface morphology of the as-deposited and annealed thin films were examined using scanning electron microscopy. The optical band gaps calculated from the UV–Vis–NIR spectra were in the range of 1.26–1.45 eV with significantly high absorption coefficients (∼105 cm−1) which is ideal for photovoltaic conversion. Moreover, the thin films were photoconductive and when incorporated into the photovoltaic structure, Glass/FTO/CdS/ASTS/C–Ag, demonstrated photovoltaic performance. The corresponding parameters Voc, Jsc, and FF were evaluated from the J-V curves yielding the values 409 mV, 1.46 mAcm−2 and 0.25 respectively.

Influence of Post-Annealing on the Structural and Nanomechanical Properties of Co Thin Films.

The correlations between the microstructure and nanomechanical properties of a series of thermal annealed Co thin films were investigated. The Co thin films were deposited on glass substrates using a magnetron sputtering system at ambient conditions followed by subsequent annealing conducted at various temperatures ranging from 300 °C to 800 °C. The XRD results indicated that for annealing temperature in the ranged from 300 °C to 500 °C, the Co thin films were of single hexagonal close-packed (hcp) phase. Nevertheless, the coexistence of hcp-Co (002) and face-centered cubic (fcc-Co (111)) phases was evidently observed for films annealed at 600 °C. Further increasing the annealing temperature to 700 °C and 800 °C, the films evidently turned into fcc-Co (111). Moreover, significant variations in the hardness and Young’s modulus are observed by continuous stiffness nanoindentation measurement for films annealed at different temperatures. The correlations between structures and properties are discussed.

Epitaxial Fe3O4 Films Grown on R-Plane Sapphire by Pulsed Laser Deposition

We have studied the influence of growth temperature and molecular oxygen pressure on the properties of thin (≤180 nm) epitaxial magnetite (Fe3O4) (001) films grown by pulsed laser deposition on R-plane single-crystal sapphire (Al2O3 ($$\bar {1}$$012)) with and without MgO seed layer. The electrical, morphological, and structural characteristics of the films have been investigated as functions of growth conditions. Fe3O4 has been shown to have a stable growth plateau at pressures in the range (4–9) × 10–5 Torr. The properties of the epitaxial Fe3O4 films grown on a MgO seed layer (5 nm thick) approach those of magnetite films grown on single-crystal MgO substrates and are superior to those of films grown on pure R-plane sapphire. The best electrical characteristic of the films and the corresponding crystal structure can be obtained at elevated growth temperatures, whereas reduced growth temperatures minimize the roughness of their surface and maximize its homogeneity. These conditions can be reconciled by high-temperature high-vacuum annealing of magnetite films grown at reduced temperatures.

Investigation of the Influences of Post-Thermal Annealing on Physical Properties of TiO2 Thin Films Deposited by RF Sputtering

For this study, titanium dioxide (TiO2) thin films were deposited on glass substrates at room temperature by the RF magnetron sputtering technique. The preparation parameters that offer better control and reproducibility of film fabrication were first optimized. Then, the effects of post-deposition annealing temperature at 350, 450, and 550°C on the microstructure, surface morphology, and optical properties of the prepared films were investigated using X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–Visible (UV–Vis) spectrophotometry. Interestingly, XRD analysis shows that as-deposited and annealed TiO2 film possess anatase crystal structure only with a preferential orientation along the (101) plane. The intensity of the (101) diffraction peak and crystallite size are found to increase with increasing annealing temperature, which indicates an improvement in the crystallinity of the films. Raman spectra confirm that all samples possess anatase phase and the crystallinity is enhanced with increasing thermal annealing. From the analysis of SEM and AFM images, it is revealed that the heat treatment significantly affects the morphology, grain size, and surface roughness of the TiO2 films. The UV–Vis spectroscopy analysis shows that as-deposited TiO2 thin film is highly transparent in the visible region with an average transmittance about 84%, whereas the transmission decreases slightly with an increase in annealing temperature. Moreover, the optical band gap energy shows a red shift with increasing the annealing temperature.

Electrical properties of partially nitrided LiCoO2 thin films with an equivalent amount of Li and Co

ABSTRACT Partially nitrided LiCoO2 thin films with stoichiometric contents of Li and Co were fabricated on sapphire substrates using an ethanol solution. The precursor films were formed by spin-coating. By thermal treatment of` the precursor films at 350, 450, 550 and 650°C for 30 min in air, four kinds of LiCoO2 thin films were obtained. That annealing of the precursor film at 650°C resulted in the nucleation of Co3O4 from the layered LiCoO2, which has been confirmed by the Raman spectrum. Three X-ray photoelectron spectroscopy peaks observed at 527.9 eV, 402.1 eV, and 396.2 eV were newly assigned to the O-Co4+, N-Co4+, and N-Co2+ bonds, respectively, using a peak-analysis technique. The resistivity of the layered LiCoO2 thin film fabricated at 650°C was measured to be 1.2 Ω cm.

Epitaxial integration of ferroelectric and conductive perovskites on silicon

BaTiO3 (BTO) and LaxSr1 − xTiO3 (x ≤ 0.15) perovskite heterostructures are deposited epitaxially on SrTiO3 (STO)-buffered Si(001) via atomic layer deposition (ALD) to explore the formation of a quantum metal layer between a ferroelectric film and silicon. X-ray diffraction and scanning transmission electron microscopy show the crystallinity of the heterostructure deposited by ALD. After postdeposition annealing of the La-doped STO film in ultrahigh vacuum at 600 °C for 5 min, x-ray photoelectron spectra show the lack of La-dopant activation when the film is deposited on 10 nm-thick BTO. The same postdeposition annealing condition activates the La-dopant when LaxSr1 − xTiO3 films are deposited on STO-buffered Si(001) surfaces consisting of 2.8 nm of STO(001) on Si(001). Annealing of LaxSr1 − xTiO3 films sandwiched between BTO and STO-buffered Si(001) layers in air at temperatures ≤350 °C preserves the La-dopant activation. Piezoresponse force microscopy demonstrates the ferroelectric behavior of BTO films grown on LaxSr1 − xTiO3 surfaces. Sheet resistance and capacitance-voltage measurements further demonstrate the conductivity of the LaxSr1 − xTiO3 films sandwiched between the BTO film and the Si(001) substrate.

Performance optimization of SnO2:F thin films under quasi-vacuum laser annealing with covering a transparent PET sheet: A study using processing map

This work presents a simple and efficient quasi-vacuum laser annealing method for photoelectric performance optimization of SnO2:F (FTO) films. This method uses a transparent polyethylene terephthalate (PET) sheet to form a quasi-vacuum environment on the film surface, which was conducive to restraining the rapid loss of laser energy and thus reinforcing the laser annealing effect. It was found that the PET-assisted laser annealing effect was closely related to the transformation of the PET sheet caused by using different laser pulse energies and defocusing amounts, and thus resulted in different surface morphology features of the FTO films. The ideal laser annealing effect could be achieved only through entirely ashing the pregenerated PET carbonized residues and avoiding laser ablation of the FTO layer. Based on the established processing map, the optimal laser pulse energy and defocusing amount for PET-assisted laser annealing of the FTO films were determined to be 90 μJ and 0.6 mm, respectively. The as-obtained FTO film was confirmed to have the best overall performance with the highest average visible transmittance of 84.5%, the lowest sheet resistance of 6.8 Ω/sq and the highest figure of merit of 2.73 × 10−2 Ω−1, indicating the prominent application superiority of PET-assisted laser annealing.

Electrodeposition of MoS2 from Dichloromethane

The electrodeposition of MoS2 from dichloromethane (CH2Cl2) using tetrabutylammonium tetrathiomolybdate ([NnBu4]2[MoS4]) as a single source precursor is presented. The electrodeposition of MoS2 from CH2Cl2 requires addition of a proton donor to the electrolyte and trimethylammonium chloride (Me3NHCl) was used for this purpose. Electrochemical Quartz Crystal Microbalance (EQCM) experiments have been employed for a detailed study of the electrochemical mechanism and to study the role of the proton donor. EQCM reveals cathodic electrodeposition of MoS2 and anodic deposition of MoS3 as well as an additional corrosion process where the deposited MoS3 strips back into solution. The electrodeposited MoS2 films are amorphous in nature. All the films were found to be homogeneous in composition across the electrode area and to be reproducible between experiments. Annealing of the as-deposited films under a sulfur atmosphere results in crystalline MoS2 as confirmed by energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy and X-ray diffraction. The deposited films were smooth and planar, as observed with scanning electron microscopy (SEM), indicating a layer-by-layer growth typical of transition metal dichalogenides.

Effect of substrates on thermoelectric properties of Ag–Sb–Te thin films within the temperature annealing

The Ag–Sb–Te (AST) thermoelectric thin film was prepared on soda-lime glass and SiO2 1-μm/Si-wafer substrates by DC magnetron sputtering method at the room temperature (RT). As-deposited thin film samples on both substrate were annealed in temperature range 573–773 K for 30 min within argon (Ar) atmosphere. The crystal structure, morphology, composition, electrical resistivity and Seebeck coefficient of as-deposited and annealed thin films are investigated. The results demonstrated that the effect of substrates was influenced the crystallinity, morphology and thermoelectric properties of the AST thin films within annealing temperature. Highlighted, the AST thin film on SiO2/Si-wafer substrate showed the highest power factor of 0.84 mW m−1 K−2 while the AST thin film on soda-lime glass substrate was around 0.053 mW m−1 K−2 at annealing temperature 773 K.

Solution-processed extremely thin films of Cu2SnS3 nanoparticles for planar heterojunction solar cells

Cu2SnS3 is a potential absorber material for thin film solar cells. However, Cu2SnS3 solar cells are normally prepared by high temperature sulfurization process. In this work, the Cu2SnS3 nanoparticle films with a porously structured surface are in situ prepared by a new and facile molecular precursor solution approach featuring a low annealing temperature (250 °C–350 °C) and a short annealing time (5 min); furthermore, the novel planar heterojunction solar cells configured as FTO/TiO2/CdS/Cu2SnS3/P3HT/MoO3/Ag are fabricated, in which poly(3-hexylthiophene) (P3HT), an organic conjugated polymer, mainly acts as hole transporting material. It is found that the annealing temperature imposes a significant influence on the structure of Cu2SnS3 nanoparticle film. While increasing annealing temperature leads to a higher crystallinity of Cu2SnS3 nanoparticle film, the pores on the film surface become larger at annealing temperature >300 °C. It is also revealed that the solar cell performance depends on the annealing temperature and Cu2SnS3 film thickness, and the efficiency of 2.03% is obtained in the solar cells with 60 nm thick Cu2SnS3 thin film prepared at 300 °C. The results here demonstrate a low-temperature solution preparation strategy to prepare Cu2SnS3 thin films for solar cells and other optoelectronic devices.

Влияние толщины пленки Pt на изменение текстуры и доли кристаллической фазы при ее отжиге

Textured Pt films with thickness h=20-80 nm were sputter deposited on oxidized c-Si (100) wafers and annealed in vacuum at 500°C/60 min. The thickness dependencies of the crystalline texture parameters and of the fraction of crystalline phase δ are obtained for as-deposited and annealed films using X-ray diffraction. The determination of δ in textured films is carried out by the new method based on rocking curve analysis. It is found that annealing leads to the texture improvement and to the increasing of δ for all h. The less h, the stronger effects of texture improvement and of δ increasing. These results are explained by the annealing-induced formation of large secondary grains whose volume fraction increases as h decreases. The inhomogeneity of the depth distributions of texture parameters and of δ are investigated for the as-deposited Pt films.

Solvent vapour annealing of methylammonium lead halide perovskite: what's the catch?

Solvent vapour annealing of hybrid perovskite films leads to stoichiometric changes, which adversely affect the photovoltaic device stability. This can be partially mitigated by incorporation of excess organic halide into the precursor solution.