Increasing Substrate Temperature Research Articles

Effect of substrate temperature on structural and optical properties of cadmium sulfide thin films prepared by evaporation thermal deposition

In this research , we study the effect of substrate temperature (423K and 473K) on structural and optical properties for thin films of cadmium sulfide (CdS) by evaporation thermal deposition method on glass substrates and the thickness was about (390nm).XRD analysis showed that CdS thin films prepared at (423K and 473K) are single crystal and have preferred orientation along (002).The grain size was found to be increased with increasing substrate temperature, in addition, the atomic force microscopy(AFM) an increase in root mean square (RMS) with an increase in substrate temperature. The absorbance and transmittance spectra have been recorded in the range off wave length(400-800nm), and it was found that the transmittance decreases with increasing substrate temperature, while the optical band gap decreases from (2.4-2.2ev)for allowed direct transition. CdS thin films should further investigated for application towards the fabrication of solar cells.

Evaluation of semiconducting p-type tin sulfide thin films for photodetector applications

Abstract Tin sulfide (SnS) is an important semiconductor as it is one of the less common p-type materials with a bandgap of 1.53 eV which makes it an attractive material for photo detector application. In the thin film form, it is a sensitive photo conductor with attractive opto-electronic characteristics. In the current report, tin sulfide thin films have been deposited by thermal evaporation in vacuum and the influence of substrate temperature on its compositional, morphological, structural, and opto-electrical properties was studied. X-ray diffraction (XRD) study shows that all the thermally deposited films are having an orthorhombic crystal structure along (111) plane as pre-dominant orientation and are polycrystalline in nature. Raman analysis verify the occurrence of SnS and Sn2S3 phases in the films. Surface morphology along with the elemental composition of the films was determined by scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS). All the films were found to be homogeneous, uniform, pin-hole free and have high optical transmittance in the UV–Vis wavelength region. The optical bandgap energy of the films was calculated using Tauc's relation and it was found to be decreasing (1.576 eV–1.429 eV) with increasing substrate temperature. The activation energy of the SnS thin films was calculated from Arrhenius plot and it was also found to be decreasing with increasing substrate temperature. The opto-electrical parameters such as photo conductivity (σL), dark conductivity (σD), response time (τr), recovery time (τd), photoresponsivity (R), and photosensitivity (S) were calculated and was found best for the films grown at 323 K.

An interplay among the Mg2+ ion coordination, structural order, oxygen vacancies and magnetism of MgO thin films

The magnetic properties of MgO thin films were discussed as an interplay among the oxygen vacancies, Mg2+ ion coordination and structural order deposited using radio frequency (RF) sputtering method by varying substrate temperature and deposition power followed by in-situ annealing. Rutherford backscattering spectrometry (RBS) and high resolution transmission electron microscopic (HRTEM) performed for these films showed decrease of film thickness with increase of substrate temperature. Films are thicker for higher sputtering powers at corresponding substrate temperatures. Spectral features in Mg K-edge near edge X-ray absorption fine structure (NEXAFS) spectra are characteristics of MgO for both sputtering powers at substrate temperature of room temperature (RT) and 350 °C. O K-edge NEXAFS spectra exhibited onset of oxygen vacancies as inferred from pre-edge region. Magnetization versus applied magnetic field curves for these films showed onset of do ferromagnetism. This behavior ceased with increase of substrate temperature, however, become dominant with increase of sputtering power. Magnetic behavior was dominant for the films which had slightly distorted Mg2+ ion co-ordination. The existence of oxygen vacancies was not observed to be consistent with magnetization. Thus, this study envisaged the role of Mg2+ ion coordination, long range structural order and oxygen vacancies in order to determine magnetism in these systems.

Substrate temperature effect on the structural and photoluminescence properties of (Y-Gd)3Al5O12:Ce3+ thin films prepared by pulsed laser deposition

Thin films of (Y-Gd)3Al5O12:Ce3+ phosphor was laser ablated on Si (100) substrates by pulsed laser deposition (PLD) method. The deposition was done under 2.7 × 10−2 mbar oxygen atmosphere and 4.5 cm target to substrate distance using 266 nm Nd:YAG laser. The effect of growth temperature on the structural, photoluminescence and optical properties is explored by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–visible spectroscopy, respectively. X-ray diffraction results show that the films crystallized in the cubic crystal structure with the crystallites’ size varying non-uniformly with the growth temperature. SEM images show non-compacted surface morphology comprising of spherical micro size particles for Ts = 100 °C and on increasing the substrate temperature, smooth surface morphologies were observed with the appearance of grain growth at 700 °C. Chemical composition analysis by the EDX method confirms the presence of Y, Gd, Al, O and Ce elements in the films, with estimated percentage atomic weight observed to depend on the growth temperature. Photoluminescence (PL) spectra show, broad band emission in the greenish yellow region attributed to the 5d to 4f electronic transitions of Ce3+. With increasing substrate temperature, a shift in PL emission to longer wavelength accompanied by changes in PL intensity was observed. Film deposited at 500 °C gave the highest PL intensity, in close agreement with the improved crystallinity from the XRD results at this temperature. UV-Vis analysis shows the films depicting high reflectance and low absorption above the visible and near infrared regions, with diffuse reflectance which depends on the growth temperature.

Origin of Conductive Nanocrystalline Diamond Nanoneedles for Optoelectronic Applications.

Microstructural evolution of nanocrystalline diamond (NCD) nanoneedles owing to the addition of methane and nitrogen in the reactant gases is systematically addressed. It has been determined that varying the concentration of CH4 in the CH4/H2/N2 plasma is significant to tailor the morphology and microstructure of NCD films. While NCD films grown with 1% CH4 in a CH4/H2/N2 (3%) plasma contain large diamond grains, the microstructure changed considerably for NCD films grown using 5% (or 10%) CH4, ensuing in nanosized diamond grains. For 15% CH4-grown NCD films, a well-defined nanoneedle structure evolves. These NCD nanoneedle films contain sp3 phase diamond, sheathed with sp2-bonded graphitic phases, achieving a low resistivity of 90 Ω cm and enhanced field electron emission (FEE) properties, namely, a low turn-on field of 4.3 V/μm with a high FEE current density of 3.3 mA/cm2 (at an applied field of 8.6 V/μm) and a significant field enhancement factor of 3865. Furthermore, a microplasma device utilizing NCD nanoneedle films as cathodes can trigger a gas breakdown at a low threshold field of 3600 V/cm attaining a high plasma illumination current density of 1.14 mA/cm2 at an applied voltage of 500 V, and a high plasma lifetime stability of 881 min is evidenced. The optical emission spectroscopy studies suggest that the C2, CN, and CH species in the growing plasma are the major causes for the observed microstructural evolution in the NCD films. However, the increase in substrate temperature to ∼780 °C due to the incorporation of 15% CH4 in the CH4/H2/N2 plasma is the key driver resulting in the origin of nanoneedles in NCD films. The outstanding optoelectronic characteristics of these nanoneedle films make them suitable as cathodes in high-brightness display panels.

Carbon films deposited by mixed-mode high power impulse magnetron sputtering for high wear resistance: The role of argon incorporation

Amorphous carbon thin films with high hardness and wear resistance have become increasingly popular for surface engineering of materials for an array of applications ranging from cutting tools to biomedical devices. For any practical application, such carbon films must resist delamination from the substrate under load. High power impulse magnetron sputtering (HiPIMS) provides an opportunity to fabricate carbon films with a wide range of sp3 fractions and thus with tuned mechanical properties. Here we used a process of mixed mode HiPIMS with transition to arc to deposit amorphous carbon films with high hardness-to-elasticity (H/E) ratio, a parameter that is often used as a measure of wear resistance. We tuned the deposition rate and the content of argon in the films by varying either the frequency of HiPIMS pulses or the substrate-to-target distance. In both cases, the argon content increased with increases in the deposition rate. Increasing deposition rate and argon content, increased the H/E ratio, while the sp3 fraction and residual stress decreased. Our results suggest that argon bombardment in a mixed mode HiPIMS process induces a dynamic annealing effect in the carbon films. We showed that H/E does not vary substantially with increasing substrate temperature alone, while the stress decreases for temperatures higher than 120 °C. Deposition at high frequencies is therefore recommended as a practical approach for the synthesis of wear resistant films, as determined by the H/E ratio.

Synthesis, structure and magnetization of Co4N thin films

Abstract We reviewed magnetic tetra metal nitrides – Fe 4 N and Co 4 N for their structure, magnetization and the thermodynamics of phase formation. Opposed to Fe 4 N , the formation of a stoichiometric Co 4 N turns out to be extremely difficult. A review of the literature of Co 4 N compound suggest that the experimental lattice parameter (LP) was always found to be smaller than the theoretical predicted value. It can also be seen that as the substrate temperature ( T s ) increases, the LP of Co 4 N film decreases. In this work, we deposited Co 4 N films using molecular beam epitaxy (MBE), direct current magnetron sputtering (dcMS) and high power impulse MS (HiPIMS). Films were characterized using X-ray diffraction, X-ray reflectivity and atomic force microscopy. It was found that at high T s , N out-diffusion significantly affects the growth of Co 4 N phase. We found that the MBE deposited films did not show any signature of Co 4 N phase when T s 703 K but at T s = 703 K , the phase formed can be assigned to fcc Co rather than Co 4 N . On the other hand, the dcMS and HiPIMS grown films clearly show the presence of Co 4 N phase even at T s = 300 K . Detailed analysis of Co 4 N films grown using dcMS and HiPIMS reveals that HiPIMS grown films are single phase and have a denser microstructure. The density of HiPIMS deposited film was also found to be close to the theoretical value. Magneto optical Kerr effect and polarized neutron reflectivity measurements were carried out to study magnetic properties. Differences in the magnetic moment and magnetic anisotropy were correlated with structural parameters. Obtained results are presented and discussed in terms of involved thin film growth mechanism.

Substrate Temperature Influence on Optical Properties of C60 Thin Films Within the Visible Range

Fullerene thin films of about 200 nm thicknesses have been deposited by thermal evaporation method on soda lime glass at substrate temperature 303 and 403K under pressure about 10-5 mbar. This study concentrated on the influence of substrate temperature on the optical properties of C60 thin films within the visible range. Optical characterization has been carried out at room temperature using the absorption spectra, at normal incidence, in range (200-900) nm.
 The absorption and extinction coefficients of the samples have been evaluated according to the variation in the UV- Visible spectrum. Increasing substrate temperature causes decreasing in optical band gap energy, for direct allowed transitions, and slightly changing in refractive index. This incident was due to the reducing of interatomic intervals, which may be correlating a decrease in the amplitude of atomic vibrations around their equilibrium sites.

Effects of growth temperature on the photovoltaic properties of RF sputtered undoped NiO thin films

Abstract In this study, nickel oxide (NiO) thin films were deposited on soda lime glass using radio-frequency magnetron sputtering at different growth (substrate) temperatures ranging from room temperature (RT) to 400 °C. The effects of substrate temperature on the structural, morphological, electrical, and optical properties were investigated. The XRD pattern unveiled a dominant peak with (2 0 0) preferential orientations for the film grown at 100 °C. However, for samples grown at high temperatures, a gradual decrease of (2 0 0) peak intensity was observed, which may be the result of the decomposition of NiO as confirmed via EDX. Surface morphology from FESEM revealed that grains were randomly orientated on the surface with maximum grain size of 19.43 nm. Upon increasing the growth temperature, the crystal quality and grain size substantially deteriorated, which is consistent with the XRD results. Scanning probe microscopy (SPM) finds rough surface with the highest surface roughness obtained at RT with a value of 1.232 nm. Electrical resistivity was found to be highly dependent on the growth temperature that decreases from 2150 Ω cm to 72 Ω cm as the substrate temperature increases. For optical properties, the optical bandgap of the NiO films decreases from 3.8 eV to 3.2 eV as a function of substrate temperature as derived from the optical transmittance data. Results show the potential application of the NiO films in photovoltaic devices.

Evaluation of hydrogen evolution reaction activity of molybdenum nitride thin films on their nitrogen content

We report preparation and electrochemical properties of molybdenum nitride MoxN (x from 1 to 2) and Mo thin films prepared by the magnetron sputtering. We adjusted amount of nitrogen during reactive sputtering, to achieve different ratios of Mo:N in the films. We could prepare well-defined and extremely smooth films. We determined hydrogen evolution reaction (HER) activity and other kinetics parameters such as Tafel slopes and exchange current densities. Corrosion stability at anodic potentials was also evaluated from onset potentials of dissolution of prepared films. We found that MoxN thin film HER activity dependence on nitrogen content in the film exhibits volcano-like diagram. From XRD measurements we identified several phases present in the films from pure Mo to β-Mo2N and δ-MoN. We find that β-Mo2N phase has the highest HER activity. Stability of studied nitrides at anodic potentials increases with increasing content of nitrogen. Mo films sputtered at high substrate temperatures exhibit higher HER activity than MoxN systems. In addition, with increasing substrate temperature during sputtering, HER activity of pure Mo thin films increases.

A Study on the Surface of RF Magnetron Sputtered CeO2 Thin Films at Relatively Low Substrate Temperature

Influences of substrate temperature on crystal structure, surface topography and surface morphology of cerium dioxide or ceria (CeO2) thin films deposited using radio frequency (RF) magnetron sputtering were studied. The substrate temperature was varied i.e. room temperature, 100, 200 and 300 °C. The characteristics of the film surface could be controlled by tuning the substrate temperature. As studied in the X-ray diffraction (XRD) analysis, the CeO2 thin films exhibited a cubic fluorite structure with predominant (200) orientation at substrate temperature of room temperature and 200 °C, while (111) preferred orientation at substrate temperature of 100 and 300 °C. The CeO2 films featured uniform surface topography and surface morphology, as observed from the atomic force microscopy and scanning electron microscopy analyses, respectively. The surface roughness and the average grain size of the films fluctuated with increasing substrate temperature. This phenomenon was suggested due to the difference in the preferential orientation of the films as in the XRD analysis.

Characterization of Methylammonium Lead Iodide Thin Films Fabricated by Exposure of Lead Iodide Layers to Methylammonium Iodide Vapor in a Closed Crucible Transformation Process

In this work, the characterization of methylammonium lead iodide (MAPI) layers fabricated with a modified two‐step deposition technique under high vacuum is presented. Thereby, PbI2, deposited in an open sublimation process, is exposed to methylammonium iodide (MAI) vapor in a closed crucible. The fabricated layers are examined with scanning electron microscopy (SEM), X‐ray diffraction (XRD), UV/VIS absorption spectroscopy, and photoelectron spectroscopy (PES). In addition, planar solar cells incorporating the MAPI layers are produced. The obtained XRD data show that MAPI with high perovskite phase purity can be fabricated in a broad substrate temperature range between 75 °C and 150 °C. The SEM measurements show that with increasing substrate temperature the morphology of the MAPI layers undergoes significant changes which can be separated into three distinct processes, taking place simultaneously: formation of the perovskite by incorporation of MAI into the PbI2 grains, recrystallization of the perovskite grains, and an Ostwald ripening like growth of the recrystallized grains. By the combination of the UV/VIS and in vacuo PES data, band diagrams for PbI2, MAI, and MAPI can be drawn which appear to be independent on the substrate temperature.

Substrate temperature effect on migration behavior of fluorocarbon film precursors in high-aspect ratio structures

The authors investigate the effect of substrate temperature on the migration of fluorocarbon film precursor species into a model high aspect ratio feature with precise temperature control and shielding from direct plasma line of sight interactions. Increased substrate temperature shows fluorocarbon deposition further into the high aspect ratio feature and scales with aspect ratio for two different width gap sizes. Modeling of the deposition behavior suggests that multiple neutral species contribute to the deposition behavior, which have different survival rates as they travel into the high aspect ratio feature and experience encounters with surfaces. The work shows how slight changes in substrate temperature can be used to control migration behavior of neutral species in high aspect ratio features.

Effect of Substrate Temperature on the Properties of Eu-Doped SrSnO₃ Phosphor Thin Films Grown by Sputtering.

Eu3+-doped SrSnO₃ (SrSnO₃:Eu3+) phosphor thin films are deposited on sapphire substrates by radio-frequency magnetron sputtering. The substrate temperature is varied from 25 to 400 °C. All SrSnO₃:Eu3+ films show amorphous behavior, while the band gap energies decrease with an increase in the substrate temperature and are determined to be 4.16-4.26 eV. The optical transmittance spectra exhibit an average transmittance of approximately 91% in the wavelength range 500-1100 nm; a gradual increase in emission intensity arising from the 5D0→7F₂ transition (618 nm) of Eu3+ is observed with increasing substrate temperature. These results suggest that the optimum substrate temperature for depositing SrSnO₃:Eu3+ red-emitting phosphor thin films is 400 °C.

Resistivity Depends on Preferred Orientation for Transparent Conductive Thin Films

An Al-doped ZnO (AZO) thin film is an important and useful material for optoelectronic devices. In this paper, pure ZnO and AZO thin films were deposited on glass substrates by using pulsed laser deposition (PLD) at different substrate temperatures from room temperature to 650°C. The effect of substrate temperature on the crystallization behavior and optoelectronic properties of the AZO thin films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), transmittance spectra and resistance measuring system, and so on. The XRD results indicated that all the samples were polycrystalline with a hexagonal wurtzite structure. As the substrate temperature was increased from RT to 650°C, the preferred orientation of the AZO thin films undergone a gradual change that affect the resistivity of the thin film. The AFM morphology also showed the same growth pattern. The average optical transmittance of over 90% in the visible range was obtained at a substrate temperature of 400°C. In addition, with increasing substrate temperature, the optical band gap decreased first and then increased, reaching a minimum at 400°C, which is the same trend as the resistivity. These results indicate that the atoms can easily diffuse from one position to another at the proper substrate temperature. The atoms trapped in non-equilibrium positions can shift to positions closer to equilibrium, which causes the Al atoms to be evenly disperse on the surface of the ZnO thin film to improve the transmittance and the conductivity.

Effect of substrate temperature on sputtered indium-aluminum-zinc oxide films and thin film transistors

Indium-aluminum-zinc oxide (IAZO) films and thin film transistors (TFTs) were prepared at different substrate temperatures by RF magnetron sputtering. Both the unannealed and annealed IAZO films exhibited an amorphous state with very flat surface topographies. An increase in oxygen vacancies and a decrease in Hall mobility with the increase of substrate temperature were observed for the annealed IAZO films. The 25°C-deposited film after annealing possessed the highest Hall mobility of 67.7 cm2/V. A slight increase in transmittance was observed after annealing with super-high average transmittances over 93.8% in the visible range and large optical bandgaps around 4.10 eV obtained for all the IAZO films. The IAZO TFT fabricated at 25 °C exhibited the best overall performance with the highest saturation mobility of 11.11 cm2/V, lowest subthreshold swing of 0.42 V/dec, lowest hysterisis of −0.31 V, and optimal threshold voltage of −5.12 V.

Magnetic anisotropy and magnetostrictive properties of sputtered Tb–Dy–Fe–Co thin films

Tb–Dy–Fe–Co thin films grown on Si $$\left\langle {100} \right\rangle$$ substrates at different substrate temperatures viz., room temperature, 300, 400 and 500 °C were investigated for structural, microstructural, magnetic and magnetostrictive properties. Grazing incidence X-ray diffraction studies showed presence of amorphous structure for the as-deposited film. Structural studies further indicated formation of (Tb,Dy)2(Fe,Co)17 and Fe–Co phases for the films grown at higher substrate temperatures. Magnetization measurements displayed presence of strong in-plane magnetic anisotropy for all the films. In addition to this, formation of out-of-plane magnetic anisotropy co-existing with in-plane magnetic anisotropy was noticed for the films grown at higher substrate temperatures. Accordingly, magnetic force microscopy studies indicated a strong out-of-plane magnetic contrast for the films grown at higher substrate temperatures. The magnetostriction estimated from tip deflection measurement was found to be negligibly small for the film grown at intermediate temperature viz., 300 °C. However, with subsequent increase in substrate temperatures the magnetostriction was found to increase. The presence of strong out-of-plane magnetic anisotropy co-existing with in-plane components was found to be detrimental for the development of magnetostriction.

An investigation on the effect of substrate temperature and substrate type on physical properties of Sb2S3 thin films prepared by spray pyrolysis

In this work, the effect of substrate temperature and substrate type on physical properties of the Sb2S3 thin film were investigated. First, Sb2S3 thin films have been deposited by spray pyrolysis method using an aqueous solution of antimony chloride and thiourea on the glass at a substrate temperature of 240 °C to 330 °C. Then, the deposition process of this layer has been done on fluorine- doped tin oxide (FTO) coated glass at a constant temperature of 300 °C. The structural, surface morphological, optical and electrical characterizations of the samples were carried out using X-ray diffraction, field effect scanning electron microscope, UV–vis spectroscopy, and four-probe apparatus, respectively. X-ray diffraction analysis showed that by increasing substrate temperature, the amorphous nature of the Sb2S3 thin film changed to the polycrystalline structure. Also, while the layer/glass sample has an individual Sb2S3 (orthorhombic) crystalline phase, the band gap values for Sb2S3 thin films prepared by increasing substrate temperature varied from 1.68 eV to 1.75 eV. Data analysis showed the Sb2S3 thin film on both substrates had a relatively high absorption coefficient (∼105 cm−1) in the visible range, and the direct bandgap had a smaller value in the layer grown on glass compared to that grown on FTO coated glass substrate. Electrical measurements exhibited the Sb2S3/FTO sample had a lower sheet resistance and resistivity than the Sb2S3/glass sample.

Atomistic simulation of the glancing angle deposition of SiO2 thin films

The classical molecular dynamics simulation of the glancing angle deposition of silicon dioxide films with practically meaningful dimensions is performed. The formation of separated slanted columnar structures is investigated for different deposition angles and different energies of sputtered silicon atoms. It is shown that a decrease in the angle between the flux of deposited atoms and the normal to the substrate leads to the decrease of column thicknesses and distances between the columns. The high-energy deposition with small deposition angles results in the formation of dense films without separate columnar structures. The increase of substrate temperature leads to partial merging of nearby columns. The glancing angle deposition with low energies of sputtered silicon atoms results in the growth of disordered columns with different dimensions, shapes, and tilt angles. Annealing of high-energy glancing angle deposited films results in partial merging of slanted columns. The obtained simulation results are in a good agreement with existing experimental data.

Investigation of properties of transparent and conducting V-doped Ga2O3 films

V-doped Ga2O3 films were prepared by using radio frequency (RF) magnetron sputtering method with different substrate temperature. The influence of substrate temperature on the properties of V-doped Ga2O3 films was investigated. The results indicated that the crystalline quality of the films increases significantly with increasing substrate temperature. All films showed a smooth surface and high visible light transmission. As the substrate temperature increased, the optical band gap of the films decreased slightly and the resistivity decreased drastically. XPS spectra revealed the valence state of V dopant in the films and two binding energies corresponding to V4+ and V5+ ions were obtained.