Surface Morphology Of Thin Films Research Articles

Side chain engineering of [1]benzothieno[3,2-b]benzothiophene (BTBT)-based semiconductors for organic field-effect transistors

[1]benzothieno[3,2-b]benzo-thiophene (BTBT)-based compounds with different side chains, 2-(2-ethylhexyl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (compound 1), 2-(2-ethylhexyl)−7-(thiophen-2-yl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (compound 2), 2-(2-ethylhexyl)−7-(5-octylthiophen-2-yl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (compound 3), and 2-(2-ethylhexyl)−7-(5-(2-ethylhexyl)thiophen-2-yl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (compound 4), were synthesized and characterized as solution-processable small molecular organic semiconductors for organic field-effect transistors (OFETs). The corresponding compounds were employed as active layers for top-contact/bottom-gate OFETs via solution-shearing method and the electrical properties were investigated. The resulting devices exhibited p-channel activity and, especially, thin films of monoalkylated BTBT with additional thiophene ring showed the highest hole mobility up to 0.12 cm2/Vs and current on/off ratio over 107. The analysis of atomic force microscopy (AFM) and X-ray diffraction (XRD) were carried out to correlate surface morphology and microstructure of thin films with the device performance.

Enhancing the ultraviolet photosensing properties of nickel oxide thin films by Zn–La co-doping

In this work, co-doping effects of transition (Zn) and rare-earth (La) elements on the crystalline structure, surface morphology, photoluminescence, optical and photosensing properties of NiO thin films are studied. NiO, NiO:Zn(1%), NiO:La(1%), and NiO:Zn(1%):La(1%) thin films are fabricated using the nebulizer spray pyrolysis (NSP) method. X-ray diffraction study revealed the cubic NiO structure of all the films. Photoluminescence (PL) spectra of thin films exhibit various emission peaks centered at the wavelengths of 387, 414, 437, 451, 477, and 521 nm. The optical bandgap energy ( E g ) values are found to be 3.46, 3.43, 3.39 and 3.33 eV for NiO, NiO:Zn(1%), NiO:La(1%) and NiO:Zn(1%):La(1%) thin films, respectively. The fabricated (Zn, La) co-doped NiO i.e., NiO:Zn(1%):La(1%) photo-detector exhibits highest responsivity ( R ), external quantum efficiency (EQE) and detectivity ( D *) values of 0.50AW -1 , 169% and 14.5 × 10 9 Jones, respectively as compared to NiO, NiO:Zn(1%) and NiO:La(1%) photo-detectors. The present study revealed that the transition and rare-earth elements co-doping can be an effective approach for tuning the various physical properties of semiconducting oxide films.

Characterization of optimized properties for InGaZnO semiconductor and thin film transistor by oxygen partial pressure

The InGaZnO thin films with varied the O2 flow ratios were deposited by a magnetron sputtering system. The effect of O2 content on the structure, surface morphology, optical and electrical properties of InGaZnO thin films is studied. Then, we investigate the relationship between bias stress stability and density of states (DOS) of thin film transistors (TFTs) with various oxygen partial pressure InGaZnO (IGZO) as the channel layer. The temperature-dependent field-effect measurements are used to calculate DOS of IGZO TFTs. With the increase of the oxygen partial pressure, the value of DOS decreases from 2.2 × 1016 to 5.5 × 1015 cm-3. Moreover, the positive gate bias stress of IGZO TFTs are investigated. Under positive gate bias stress, the transfer curves of IGZO TFTs with various oxygen partial pressure show an obvious shift, the value of threshold voltage shift () is 5.1, 2.94, 2 and 0.8 V, respectively. The results suggest that the device with a smaller DOS is more stable than others. Therefore, this study offers a brief and accurate method to demonstrate instability mechanism of IGZO TFTs.

Structural and optical characteristics of thermally evaporated TlGaSe2 thin films

The present paper reports the structural and optical properties of thermally evaporated TlGaSe2 thin films. X-ray diffraction pattern of evaporated film presented two diffraction peaks around 24.15 and 36.00° which are associated with planes of monoclinic unit cell. Surface morphology of the TlGaSe2 thin films was investigated by scanning electron and atomic force microscopy techniques. Although there was observed some ignorable amount of clusters of quasi-spherical shape in the scanning electron microscope image, the film surface was observed almost uniform. Raman spectrum exhibited six peaks around 253, 356, 488, 800, 1053 and 1440 cm−1 associated with possible vibrational mode combinations. Band gap energy of the thin film was determined as 3.01 eV from the analyses of transmission spectrum. Transmission spectrum presented strong Urbach tail and analyses of corresponding region resulted in Urbach energy of 0.66 eV. The structural and optical properties of deposited TlGaSe2 thin films were compared with those of single crystal. This comparison would provide valuable information about influence of thickness on the studied compounds.

Synthesis, characterization and supercapacitive application of nanocauliflower-like cobalt tungstate thin films by successive ionic layer adsorption and reaction (SILAR) method

For the first time, cobalt tungstate (CoWO4) thin films were synthesized by successive ionic layer adsorption and reaction (SILAR) method. The monoclinic crystal structure of CoWO4 film was confirmed from X-ray diffraction (XRD) technique. The elemental, surface morphological, structural, and electrical analyses were executed using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDAX), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), two point probe method, and contact angle measurement techniques. The surface morphology of CoWO4 thin film consisted of islands of agglomerated cauliflower-like spherical nanoparticles with hydrophilic nature. The specific surface area of 60 m2 g−1 with an average pore size of 1.10 nm. The CoWO4 thin film electrode exhibited specific capacitance of 1436.5 F g−1 at a scan rate of 2 mV s−1 in 1 M KOH as well as capacitance retention of 94% over 3000 galvanostatic charge discharge (GCD) cycles. Furthermore, flexible solid-state symmetric supercapacitor (FSS-SSC) device assembled using CoWO4 thin films, showed specific capacitance of 101.32 F g−1, specific energy of 14.07 Wh kg−1 and specific power of 1225.25 W kg−1. This work highlights simplistic preparation of CoWO4 thin films for energy storage application.

Transparent SiOxCyHz Barrier Film Prepared by Roll to Roll PECVD

This paper uses plasma-enhanced chemical vapor deposition (PECVD) to successfully fabricate silicon oxide films on silicon dioxide substrates for supporting layers of uncooled infrared focal plane array microbridge structures. In this paper, the thickness, refractive index, growth rate, and other parameters of the films were measured using the XP-2 step meter and ellipsometer. At the same time, atomic force microscopy (AFM) was used to study the surface morphology of the films. The experimental results show that deposition temperature and ICP power are the main factors affecting the growth rate of thin films. Deposition temperature is a crucial factor affecting the surface morphology of thin films.

Качественный и количественный анализ морфологии поверхности порфириновых пленок

The surface morphology of tetraphenylporphyrin thin polycrystalline films – H2TPP and ZnTPP obtained by vacuum condensation under quasi-equilibrium conditions is analyzed by sc. The use of analytical methods for processing images of the organic films surface obtained by standard methods, allows to identify not only qualitative, but also quantitative characteristics of the polycrystalline films structure: the average grain size, grain size distribution, the presence of texture and characteristic of crystallites orientations. It is shown that free based H2TPP tetraphenylporphyrin films have a more pronounced texture and a larger crystallite size than ZnTPP, which is due to the peculiarities of self-organization of molecules, if condensation occurs under the same conditions. The applicability of this method of image analysis for obtaining information about the structure and morphology of the surface of thin organic films during vacuum condensation is shown.

Influence of Synthesizing Temperatures on the Crystallinity, Morphology and Band Gap of CdSe Thin Films

CdSe thin films were deposited using Chemical Bath Deposition (CBD) by maintaining the bath at 20 °C, 40 °C, 60 °C and 80 °C temperatures. The thin films were deposited on ordinary glass substrates then characterized for their crystallinity, morphological and optical properties. From the X-ray Diffraction (XRD) analysis; it was revealed that there was a significant difference in crystallinity and the UV-vis spectroscopy enhanced the study of the energy band gaps which showed a drastic shifting. The study performed on the surface morphologies of the CdSe thin films exhibited a double layer of deposition; but did not show considerable difference from each other for different temperatures. The EDS pattern helped in determining the stoichiometric ratio.

The impact of fluence dependent proton ion irradiation on the structural and optical properties of Bi5In30Se65 thin films for nonlinear optical devices

This paper reports the effects of ion irradiation on the structural, linear, and nonlinear optical properties of thermally evaporated Bi5In30Se65 thin films. The prepared films were irradiated with 30 keV proton ions with different fluences, such as 5 × 1015 ions per cm2, 1 × 1016 ions per cm2, and 5 × 1016 ions per cm2. Structural analysis via X-ray diffraction (XRD) confirmed the non-crystalline nature of the film after ion irradiation with different doses. However, after the irradiation dose, the surface morphology changed, as shown by atomic force microscopy (AFM) images and field emission scanning electron microscopy (FESEM) images. The compositions of the films were obtained using energy-dispersive X-ray spectroscopy (EDX). Optical analysis via UV-Visible spectroscopy showed a reduction in the transmittance and an increase in the absorption in the higher wavelength region with irradiation. The optical bandgap and Tauc parameter decreased with an increase in the irradiation fluence, which is due to an increase in the irradiation-induced defects and disorder inside the system. The increases in the third order nonlinear susceptibility and the nonlinear refractive index with ion fluence are useful for nonlinear optical applications. The linear refractive index calculated from the transmittance data increased, satisfying Moss's rule. The optical parameters, such as lattice dielectric constant, optical density, skin depth, optical conductivity, real and imaginary dielectric constants, optical conductivity, loss factor, VELF, and SELF, were calculated using several empirical relationships and showed increasing behavior with the ion irradiation dose. The changes obtained in both the linear and nonlinear parameters will be useful for nonlinear optical device applications.

Termal Buharlaştırma ile Üretilen Cu2-xSe İnce Filmlerin Yapısal, Morfolojik ve Optik Özellikleri Üzerine Araştırma

In this work, the influence of post-annealing on the structural, morphological, and optical properties of copper selenide thin films deposited on glass substrate by thermal evaporation was investigated in detail. The post-annealing process at different ambient temperatures in a nitrogen atmosphere was applied to thin films deposited at room temperature. The X-ray diffraction (XRD) patterns showed the presence of cubic Cu2-xSe phase, and it was observed that the crystallinity improves with increasing annealing temperature. In addition, it was deduced that the average crystallite size increased with the annealing temperature. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the surface morphology of thin films. It was seen that all samples have compact and densely packed surface morphology and grains on the surface become larger. Surface roughness increased from 11nm to 53 nm as the annealing temperature increased. On the other hand, the optical properties of as-deposited and annealed thin films were investigated by utilizing a UV-Visible spectrophotometer. The direct bandgap energies of as-deposited and annealed samples were estimated to be 2.34 eV, 2.31 eV, and 2.29 eV by using the well-known Tauc relation, respectively. The direct bandgap energy of thin films was also calculated using the derivative spectroscopy technique.

Plan-view TEM observation of a single-domain κ-Ga2O3 thin film grown on ε-GaFeO3 substrate using GaCl3 precursor by mist chemical vapor deposition

We demonstrated the growth of a single-domain κ-Ga2O3 thin film on ε-GaFeO3 by using an organic-free compound as a precursor for mist chemical vapor deposition. X-ray diffraction analysis revealed that an 86 nm thick κ-Ga2O3 thin film was grown almost coherently with slight lattice relaxation. The surface morphology of the κ-Ga2O3 thin film exhibited a step-terrace structure without island growth. Furthermore, plan-view TEM observations revealed that the κ-Ga2O3 thin film grown on ε-GaFeO3 had a single domain, whereas the previously reported κ-Ga2O3 thin film grown on AlN template had a domain structure.

Synthesis of n-type ZrO2 doped ε-Ga2O3 thin films by PLD and fabrication of Schottky diode

Tin-assisted pure phase n-type ZrO2-doped ε-Ga2O3 films were synthesized by pulsed laser deposition (PLD) and deposited on (0001) epi-GaN/sapphire substrates. The characterization of n-type ZrO2-doped ε-Ga2O3 thin films and the electrical properties of SBD based on that film were investigated in details. From XRD, the pure Zr-doped ε-Ga2O3 without diffraction peaks of zirconia suggested the formation of ε-(ZrxGa1−x)2O3 solid solution. The surface morphology and chemical content of the ε-Ga2O3 thin film were studied by AFM and XPS. The electrical resistivity and related free carrier concentration at room temperature were measured to be 108 Ω·cm and 5.5 × 1015 cm−3, respectively, and mobility up to 10.3 cm2/V·s. The Schottky barrier diode possessed a rectification ratio up to 106~107, breakdown voltage of 392 V, and the interface states density from 2.4 × 1013 cm-2 eV-1 to 6.4 × 1014 cm-2 eV-1 with the trap energy level from 0.89 eV to 0.94 eV below the bottom of the conduction band.

Impact of surface morphology and thickness of tin selenide thin films on their optical properties

Thin tin selenide (SnSe) films were synthesized on polyamide sheets via the two-stage adsorption/diffusion method. The surface morphology and chemical composition of the hereby obtained thin film were characterized by energy-dispersive spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and X-ray photoemission spectroscopy techniques. The X-ray diffraction analysis showed that the obtained films are chemically close to tin selenide with three orthorhombic phases. A systematic investigation was carried out to understand the factors of the next stage process, the influence of conditions on the structure, the surface morphology of SnSe thin films, and their thickness. It was found that the concentration of tin(II) precursor solution, its pH value, and temperature led to the creation of films of various thickness and surfaces with different features. The SnSe films consisted of nanoscale ∼40 nm size grains, which in turn were combined into agglomerates of up to 100 nm to 3 µm. The stoichiometric ratios of tin and selenium in SnSe films were also dependent on the next-stage conditions of the synthesis process. The thickness of the SnSe films and the size of the crystallites of which they are composed have a decisive influence on the optical properties of these layers and the band gap of which varied in the range of 1.75–1.24 eV.

Local structure and structural properties of vanadium oxide thin films prepared by radio-frequency reactive magnetron sputtering at various oxygen flow rate

In this work, vanadium oxide thin films were prepared by using radio frequency reactive magnetron sputtering with vanadium metal target. The effect of O2 flow rate was investigated in terms of vanadium oxide thin films by varying O2/Ar flow rate at 1/20, 2/20, 3/20, 4/20, 5/20, 6/20 (in sccm unit) with fixed RF power at 200 W and sputtering time at 80 minutes. The surface morphology and crystal structure of V2O5 thin films were investigated by scanning electron microscope (SEM), atomic force microscope (AFM), and X-Ray Diffractometer (XRD) respectively. The influence of the O2/Ar ratio on a local structure of vanadium oxide thin films was studied by the Synchrotron x-ray absorption spectroscopy (XAS) technique. The oxidation states of vanadium oxide thin films were measured at V K-edge by the x-ray absorption near-edge structure (XANES). The results of XANES spectra at the V K-edge showed that the prepared films under the O2/Ar flow rate at 1/20 sccm contained the vanadium with the oxidation states of V3+ and V5+ while the others contained only V5+. This is because the higher O2/Ar flow rate possibly causes an increase in energy flux at the substrate and the 1s→3d transition peak’s intensity, which could lead to a higher deposition rate. To achieve the desired V2O5 structure, the gas flow rate could be adjusted properly. The evolution of the local structure around V atoms was studied using the extended x-ray absorption fine structure (EXAFS) which supported the XANES results indicating that the structural environment around V atoms is in good agreement with the V2O5 orthorhombic structure. Finally, XANES and EXAFS fitting results confirmed that the O2 flow rate affected the local structure of vanadium oxide thin films.

Effect of 2 MeV W+ ion irradiation on the surface morphology of Sc:In:C and Zr:In:C thin films

In this work, a comparative study of surface morphology and elemental distribution of thin films of the M:In:C (with M = Sc or Zr) ternary composites irradiated with 2 MeV W ions with fluences 10 cm and 10 cm was carried out. The films were prepared by ion beam sputtering of the M, In and C targets followed by thermal annealing in a high vacuum. The surface morphology was monitored by Atomic Force Microscopy (AFM), and the elemental composition by Rutherford Backscattering Spectroscopy (RBS) in the regime of elastic scattering (2000 keV He ions energy) and nuclear resonant scattering (3046 and 4280 keV He ions for O and C resonances, respectively). It has been shown that both deployed modifications (thermal annealing and ion beam irradiation) seriously affect the surface morphology and the elemental distribution of both composites. It turned out that the main reason for the changes is a decrease in the content of indium in the composites, which after irradiation with a high fluence of 10 cm decreased to almost zero. It also turned out that the morphological changes take place differently in the inspected composites - more significantly in Zr:In:C, less in Sc:In:C.

Experimental and In Silico studies on optical properties of new thiadiazole tetrasubstituted metal-free and zinc phthalocyanine compounds

In this study, 2-amino-5-phenyl-1,3,4-thiadiazole substituted metal-free phthalocyanine (H2Pc) was synthesized by tetramerization reaction of the phthalonitrile derivative. The synthesized compound was characterized by IR, UV–Vis, 1H NMR, MS spectroscopy and elemental analysis. To determine the potential of the synthesized phthalocyanines to be used in optical applications (thiadiazole substituted metal-free and zinc(II) derivatives), photoluminescence and fluorescence properties of compounds were studied. In addition, the powder and thin film surface morphology of these compounds were examined by scanning electron microscope (SEM). The electronic features (chemical hardness, electron affinity, electronegativity) and frontier orbital energy levels (HOMO-LUMO) were computed using density functional theory. The HOMO-LUMO energies of (H2Pc) and zinc(II) phthalocyanine (ZnPc) were acquired close to each other. The spectroscopic studies showed that the UV–visible spectra obtained using time-dependent density functional theory (TDDFT) was compatible with the experimental UV–visible study. The nonlinear optical (NLO) results indicated that the NLO properties of H2Pc are slightly better than ZnPc.

The Study of Optical and Electrical Properties of Nanostructured Silicon Carbide Thin Films Grown by Pulsed-Laser Deposition

In this paper, nanostructured silicon carbide (SiC) thin films are deposited onto glass substrate using pulsed laser deposition technique. Electrical and optical characterizations such as conductivity, resistivity, transmission, Seeback effect, absorption, absorption coefficient, energy band gap, and extinction coefficient as a function of photon energy, and the effect of thin films thickness on transmission are carried out to characterize the prepared samples. Results showed that the prepared SiC thin film is an n-type semiconductor with an indirect bandgap of ~3 eV, 448 nm cutoff wavelength, 3.4395 × 104 cm−1 absorption coefficient and 0.154 extinction coefficient. The surface morphology of the SiC thin films is studied using scanning electron microscope at a substrate temperature of 400 °C and it is found that the grain size of the prepared SiC thin film is about 30 nm. As such, the nano thin films optical and structural characteristics enable the films to be used as gases sensors in many optoelectronic devices such as the environment and ultraviolet photodiode.

Preparation and properties of antibacterial PVDF composite thin films

As medical dressings, polyvinylidene fluoride (PVDF) thin films loaded with antimicrobial agents offer excellent wound infection control. In this study, PVDF/tea polyphenol (TPs) and PVDF/TPs/Ag composite thin films were prepared by electrically assisted three-dimensional (3D) printing method. The surface morphology, hydrophilicity, and antibacterial properties of the composite thin films were studied. The results showed that the presence of appropriate amount of TPs promoted the crystallinity and β-phase content of the PVDF thin films, and TPs played an important role in the formation of abundant holes on the surface of PVDF films. It facilitated the deposition of silver nanoparticles on the surface of PVDF thin film and improved the uniformity of their distribution. The Escherichia coli (E. coli) inhibition rate of the PVDF/TPs composite thin film reached 97.22%. The antibacterial activity of this composite thin film improved significantly after the deposition of silver nanoparticles, and the E. coli inhibition rate of the PVDF/TPs/Ag composite thin film was 99.58%.

Enhancing electrical properties of carbon nanotubes thin films by silicon incorporation

Silicon incorporated carbon nanotube (Si-CNTs) thin films was prepared by radio frequency plasma enhanced chemical vapor deposition technique. Tetraethyl orthosilicate solution was used for incorporation of silicon in CNTs thin films. Energy dispersive X-ray analysis shows that the silicon atomic percentage was varied from 0 % to 6.1 %. The chemical binding energies of carbon and silicon were analyzed from X-ray photoelectron spectroscopy data. The various peaks at ~531 eV, ~ 285 eV, ~155 eV and ~104 eV was observed in the XPS spectra due to the oxygen, carbon and silicon respectively. Surface morphologies of Si-CNTs thin films have been analyzed by field emission scanning electron microscopy, which revels that the length of the silicon incorporated carbon nanotubes ~500 nm and corresponding diameter ~80 nm. The room temperature electrical conductivity was increased whereas the activation energy was decreased with the increase of atomic percentage of silicon in Si-CNTs thin films. The room temperature electrical conductivity was increased from 4.3 × 103 to 7.1 × 104 S cm−1 as the silicon atomic percentage in Si-CNTs thin films increases from 0 to 6.1 % respectively.

Structural, optical and half-metallic properties of Mn and As co-implanted ZnO thin films

In this work, we use ion implantation to implant Mn ions and As ions into the ZnO films prepared by molecular beam epitaxy.The surface morphology and crystalline structure of ZnO thin films are investigated by X-ray diffraction, atomic force microscopy and Raman spectroscopy. First-principles calculations discover the half-metallic property of the ZnO films implanted with Mn ions. The effects of Mn ions and As ions implantation on the absorption edges, refractive index (n), extinction coefficient (k) and dielectric constant of ZnO films are studied by transmission spectra, absorption spectroscopy and spectroscopic ellipsometric technique. From the spectroscopic ellipsometry (SE), the n and k of the films have increased after ion implantation. Due to the half-metallic properties of the Mn-implanted ZnO film, the variation trend of the peaks of n and k with wavelength is much gentler than the peak of unimplanted ZnO film. The dielectric constant measured by SE and the results of photoluminescence spectra reveal that the electron transition of ZnO films is weakened by Mn ions implantation. The results provide a new direction for the design and optimization of optoelectronic devices based on ZnO thin films with semi-metallic properties.