Effect Of Substrate Temperature Research Articles

Effect of substrate temperature on properties of AlN buffer layer grown by remote plasma ALD

Aluminum nitride (AlN) thin film has considerable properties, which makes it advantages for a variety of applications. AlN films were prepared by remote plasma atomic layer deposition (RP-ALD) with the growth temperature of 100 to 450 °C. The properties of AlN films with various growth temperatures were studied systematically. In addition, AlN/GaN layers deposited on sapphire (Al2O3) substrates were also investigated. The AlN/GaN interfaces and AlN/Al2O3 interfaces characteristics were analyzed. The optical property of GaN films prepared on sapphire substrates with and without AlN buffer layer were identified by photoluminescence measurement. The experiment result shows that crystal AlN films became to present at 250 °C with a hexagonal wurtzite structure. X-ray photoelectron spectroscopy investigation shows that AlN films contain Al-O, Al-O-N complexes and Al-Al metallic aluminum bonds except the main Al-N bond confirmed by high resolution Al 2p and N 1 s spectra. High-resolution transmission electron microscopy measurement reveals sharp interfaces of AlN/Al2O3 and AlN/GaN. The obtained lowest lattice mismatch of AlN/Al2O3 and AlN/GaN are 11.0% and 2.1%, respectively. Photoluminescence measurement further confirms that AlN buffer layer enhances the quality of GaN grown on sapphire substrates. High quality AlN/GaN layers prepared by RP-ALD provides a promising pathway towards high quality GaN-based devices.

Substrate temperature effects on the structural, morphological and optical properties of Bi2S3 thin films deposited by spray pyrolysis: An experimental and first-principles study

Bismuth sulfide (Bi2S3) nanostructured films were deposited on glass substrates using a spray pyrolysis method. Herein, we present a study of the effect of substrate temperature (TS) on the structural, morphological, and optical properties of the prepared nanocrystalline thin films. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed the formation of polycrystalline orthorhombic Bi2S3 films. The crystallite size and micro-strain of the films changed as the substrate temperatures was varied. Scanning electron microscopy (SEM) images show a compact and dense surface, with a uniform spatial distribution of nearly spherical grains. Energy-dispersive X-ray spectroscopy (EDS) studies confirm the prevalence of Bi and S elements in the films, being films deposited at a temperature of 400 °C sulfur deficient. The crystallite size increases from 18 to 22 nm when Ts varies from 400 °C to 300 °C. The optical band gap of the films was found to vary between 1.44 and 1.58eV, while a high absorption coefficient (>104 cm−1) was measured in the visible and near-infrared spectral ranges. These experimental results were compared with ab initio calculations performed in the framework of the density functional theory (DFT). The band structure and density of states (DOS) of the Bi2S3 compound reveal an n-type semiconductor with a direct gap of about 1.52 eV. Both experimental and theoretical results provide strong evidence that our bismuth sulfide thin films can be suitable materials for light-harvesting in solar cell devices.

Effect of substrate temperature on the structural, optical, electrical, and morphological properties of zinc oxide thin films

Effect of substrate temperature on the structural, optical, electrical, and morphological properties of zinc oxide thin films

Effects of Substrate Temperature on Properties of Sb-doped SnO2 Thin Film

Effects of Substrate Temperature on Properties of Sb-doped SnO2 Thin Film

Explosive boiling of water films based on molecular dynamics simulations: Effects of film thickness and substrate temperature

This paper deals with investigations of mechanisms governing explosive boiling of water films on hot copper substrate with plain surface. The investigations are based on results of molecular dynamics (MD) simulations in which film thickness (7.5 nm, 17 nm and 25.5 nm) and substrate temperature (800 K, 700 K and 600 K) are set as parameters. Analyses of heating transients, which lead to explosive boiling event, are done comparing the following quantities for considered MD configurations: time instant of explosive boiling onset, dynamics of vapour generation, increase of water film thickness due to thermal expansion and vapour generation, evolution of water temperature as well as heat transfer from the copper substrate to the water film. These analyses have shown that explosive boiling onset is related neither to the value of substrate temperature nor to the film thickness in a straightforward way. The investigations of temperature and per atom energy in the water region near the heating substrate surface have revealed that beside thermal also mechanical mechanisms can play significant role in triggering of explosive boiling. The mechanical mechanisms, related to pressure wave propagation in liquid film, comprise occurrence of tensile stresses which induce / intensify generation of vapour phase in the near wall region. The obtained results show that thermal effects are dominant in cases with high substrate temperature and thick liquid films as in these configurations the water temperature reaches spinodal value and explosive boiling is triggered before expansion wave reaches the near wall region. In cases when water in the near wall region is strongly overheated (but well below spinodal temperature), tensile stresses induced by expansive wave propagation cause intensive vapour generation and contribute dominantly to occurrence of explosive boiling. Finally, in cases with lower substrate temperature and thin liquid films, an interplay of thermal and mechanical mechanisms leads to explosive boiling. Beside these, the disjoining pressure seems to play a role in cases with thin liquid films.

Effect of Substrate Temperature on the Electrical Properties of Al-doped Zinc Oxide Films Deposited on Polyethylene Terephthalate

To prepare homogeneous thin films of zinc oxide (ZnO) doped with aluminum (Al) on a polyethylene terephthalate (PET) substrate at different temperatures (200-250 °C), the process is carried out by utilizing the chemical spraying pyrolysis approach. A study of the effects of substrate temperature on the Al-doped Zinc Oxide (AZO) films' electrical characteristics and roughness is performed. The measurements of atomic force microscopy (AFM) shows that the root mean square (RMS) roughness of the AZO films is increased with the increase of PET substrate temperature. Hall measurements show that the electrical resistivity decreases as the substrate temperature increases. Upon the increment of substrate temperature, there is an increase in the carrier concentration value from 9.98 × 1019 to 5.4 × 1020 cm−3 and an increase in the carrier mobility value from 5.5 to 9.76 cm2.(V. S)−1.

Deposition Mechanism and Properties of Plasma-Enhanced Atomic Layer Deposited Gallium Nitride Films with Different Substrate Temperatures

Gallium nitride (GaN) is a wide bandgap semiconductor with remarkable chemical and thermal stability, making it a competitive candidate for a variety of optoelectronic applications. In this study, GaN films are grown using a plasma-enhanced atomic layer deposition (PEALD) with trimethylgallium (TMG) and NH3 plasma. The effect of substrate temperature on growth mechanism and properties of the PEALD GaN films is systematically studied. The experimental results show that the self-limiting surface chemical reactions occur in the substrate temperature range of 250-350 °C. The substrate temperature strongly affects the crystalline structure, which is nearly amorphous at below 250 °C, with (100) as the major phase at below 400 °C, and (002) dominated at higher temperatures. The X-ray photoelectron spectroscopy spectra reveals the unintentional oxygen incorporation into the films in the forms of Ga2O3 and Ga-OH. The amount of Ga-O component decreases, whereas the Ga-Ga component rapidly increases at 400 and 450 °C, due to the decomposition of TMG. The substrate temperature of 350 °C with the highest amount of Ga-N bonds is, therefore, considered the optimum substrate temperature. This study is helpful for improving the quality of PEALD GaN films.

Influence of growth temperature on microstructural and electromagnetic properties of nickel thin films

Nickel thin films were grown on quartz substrates in ultra‐high vacuum at laser fluence of 98 J/cm2 using pulsed laser deposition. Effects of substrate temperature on the electromagnetic properties of the films were investigated. XRD data reveal crystalline growth at substrate temperature (Ts) of 500°C. Roughness of the thin films at Ts of 100°C was noted as 8 nm which was decreased to 3 nm at 500°C. Coercive field and electrical resistivity were decreased from 10 to 5 mT and 0.71 to 0.064 μΩ‐m, respectively, at higher substrate temperature. Magnetoresistance for both modes of configuration and Hall mobility were decreased, while carrier density and Hall coefficient showed opposite behavior with increased substrate temperature.

Effect of substrate and annealing temperature on the physical properties of the thin films of SnSe2-SnSe alloy

Thin films of SnSe2-SnSe alloy were deposited at substrate temperatures 300 and 473 K by thermal evaporation. The 473 K as-deposited layers were re-grown on annealing from 523 to 623 K. The films show mixed phases of hexagonal SnSe2 and orthorhombic SnSe and display corresponding vibrational modes. The unit cell parameters and axes strain of the layers vary and show crystallite size distributions with changes in annealing temperature (Ta). Moreover, the film smoothness increases at elevated temperatures. The films as-deposited at 300 K exhibit direct bandgaps (Eg) of 1.15 and 1.52 eV. Further, the Eg values of 473 K layers vary from 1.47 to 1.56 eV with a change in temperature from 523 to 623 K and show an absorption coefficient (α) ≥ 5 × 104 cm−1. In addition, the refractive index (n) decreases, and optical mobility (μopt) increases with an increase in Ta. The above optical response indicates the films to be optically active and suitable in photonic devices in the visible and NIR portion of the EM spectrum. The PL emission peaks were observed at 805.1 and 1064.22 nm, which confirmed the presence of direct bandgaps of the SnSe2 and SnSe phases.

Effect of substrate temperature and precursor salt molarities on the nickel oxide physical properties

Effect of substrate temperature and precursor salt molarities on the nickel oxide physical properties

Temperature optimization of NiO hole transport layer prepared by atomic layer deposition

Atomic layer deposited (ALD) nickel oxide (NiO) thin film is frequently utilized as a hole transport layer (HTL) for perovskite solar cells (PSCs). Particularly nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)2) precursor and ozone reactant are used for NiO film deposition. The substrate temperature effect on the stoichiometric composition for oxygen vacancies defects and electrical properties such as mobility is crucial, affecting further device performance. In the present study, NiO thin films are grown using the ALD method at a substrate temperature range between 180 to 250 °C on SiO2/Si substrates. Next, the effect of substrate temperature on the film composition, valence levels, nickel oxidation states, oxygen vacancies, and electrical properties was systematically examined, not to mention film growth, thickness, morphology, crystallinity, and optical properties. At 180 °C, the film growth rate was 0.017 nm/cycle, which was increased to 0.025 nm/cycle at 250 °C. All grown NiO films exhibited polycrystalline cubic crystal orientation, and the (200) plane simultaneously Ni3+ phase coexists with the Ni2+ phase. Furthermore, the electrical resistivity and mobility increased from 2.36 – 3.24 × 102 Ω.cm and 9.6–21.9 cm2V−1s−1 with substrate temperatures of 180 °C–230 °C. The prepared NiO films were optically transparent, >70% in the visible region, and the Ultraviolet photoelectron spectroscopy (UPS) study revealed that the variation in the valance band and conduction bands critically depended on the growth temperature. Thus, our findings reveal that the chemical and electrical characteristics of deposited NiO thin film are precisely influenced by substrate temperature; it will also offer considerable promise for developing NiO HTL concerning PSCs device improvement.

Effect of substrate temperature on the optical properties of DC magnetron sputtered copper oxide thin films

Copper oxide thin films are deposited on quartz substrates by DC magnetron sputtering and the effect of deposition temperature on the optical properties is examined in detail. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) analysis, Raman spectroscopy, UV–vis spectroscopy, and four-probe sheet resistance measurements are used to characterize the surface morphology, structural, optical, and electrical properties of the deposited films respectively. Sputter deposition is carried out with the substrate at room temperature and at elevated temperatures between 200 and 300 °C. XRD analysis indicates that the oxide formed is primarily Cu2O and the absorption spectra show a critical absorption edge at around 300 nm. The sheet resistance gradually decreases with increase in deposition temperature, corresponding to an increase in the conductivity of the films. Also observed is an increase in the band gap energy from 2.02 eV for room temperature deposition to 2.35 eV at 300 °C, corresponding to an improved film crystallinity and reduction in defect density. The band gap energy and the variation of sheet resistance with substrate temperature shows that the microstructure plays a vital role in their behavior. These transformation characteristics are of huge technological importance having variety of applications including transparent solar cell fabrication.

Effect of substrate temperatures on structural, optical and dispersion energy parameters of RF sputtered nickel oxide thin films

Thin films of nickel oxide (NiO) have been widely identified as a promising ion storage layer in electrochromic devices owing to their excellent electrochemical properties. There is, however, a lack of accurate description of their optical parameters, which are quite important to explore the optical and electrochromic characteristics of NiO. In the present investigation, nickel oxide (NiO) thin films have been deposited using radio frequency (RF) magnetron sputtering at different substrate temperatures (Tsub) viz. 100, 200 and 300 °C. The consequences of substrate temperature on the structural, morphological, optical, and vibrational properties were examined. The XRD pattern showed increased crystallinity with an increase in substrate temperature. Surface morphology revealed an ultrafine and smooth morphology. The average optical transmittance varied between 64% and 85%. Shrinkage in the energy bandgap was observed with the change in substrate temperature. The values of optical parameters like refractive index (n), extinction coefficient (k), the real part of the dielectric constant (ε1), the imaginary part of the dielectric constant (ϵ2), and porosity of NiO films were found to change with an increase in substrate temperature. The effect of substrate temperature on dispersion energy parameters (Eo and Ed) derived from the Wemple-DiDomenico model was calculated and discussed in detail. Room temperature photoluminescence studies revealed peaks along 3.39 eV (365 nm) and 2.95 eV (420 nm) nm as a consequence of band-band PL phenomena for nickel oxide and defects. In the Raman spectrum, one predominant peak around 560 cm−1 corresponds to the one-phonon LO mode, and another minor peak at 1100 cm−1 owing to the two-phonon LO mode were observed, which arises from Ni–O vibrations. The observed results reveal the potential application of the NiO films in optoelectronic and electrochromic device applications.

The Microstructures and Characteristics of NiO Films: Effects of Substrate Temperature.

The influence of the substrate temperature on the structural, surface morphological, optical and nanomechanical properties of NiO films deposited on glass substrates using radio-frequency magnetron sputtering was examined by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Visible spectroscopy and nanoindentation, respectively. The results indicate that the substrate temperature exhibits significant influences on both the grain texturing orientation and surface morphology of the films. Namely, the dominant crystallographic orientation of the films switches from (111) to (200) accompanied by progressively roughening of the surface when the substrate temperature is increased from 300 °C to 500 °C. The average transmittance of the NiO films was also found to vary in the range of 60-85% in the visible wavelength region, depending on the substrate temperature and wavelength. In addition, the optical band gap calculated from the Tauc plot showed an increasing trend from 3.18 eV to 3.56 eV with increasing substrate temperature. Both the hardness and Young's modulus of NiO films were obtained by means of the nanoindentation continuous contact stiffness measurements mode. Moreover, the contact angle between the water droplet and film surface also indicated an intimate correlation between the surface energy, hence the wettability, of the film and substrate temperature.

Overcoming metal-rich surface chemistry limitations of ScAlN for high electrical performance heterostructures

While metal-rich ScAlN epitaxy has traditionally led to mixed phase films by controlling the surface chemistry with transient metal doses utilizing a pulsed method of molecular beam epitaxy, phase-pure, metal-rich epitaxy of ScAlN was demonstrated, showing improved structural and electrical characteristics. The effects of substrate temperature and III/V ratio were studied, and an x-ray diffraction figure of merit and surface roughness as low as 225 arcsec and 0.68 nm, respectively, were demonstrated. A significant catalytic effect is observed with the use of Sc in metal-rich conditions, resulting in varied growth rates with substrate temperature and Sc surface coverage. This catalytic effect results in complications when selecting synthesis conditions and for in situ monitoring and can be accounted for improved phase purity. The variation of growth rates with Sc surface coverage introduces non-linearities to the transient initiation stage of growth but also introduces a feedback stabilization of the surface chemistry. Accounting for these complexities, a Sc0.2Al0.8N high electron mobility transistor (HEMT) heterostructure is demonstrated with a sheet resistance of 152 Ω/□, a mobility of 700 cm2/Vs, and a sheet charge of 5.9 × 1013 cm−2.

Effect of Substrate Temperature on the Structural, Optical and Electrical Properties of DC Magnetron Sputtered VO2 Thin Films.

This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, microstructure, optical and electrical properties of the films were investigated. The results show that TS below 500 °C favors the growth of V2O5 phase, whereas higher TS (≥500 °C) facilitates the formation of the VO2 phase. Optical characterization of the as-prepared VO2 films displayed a reduced optical transmittance (T˜) across the near-infrared region (NIR), reduced phase transition temperature (Tt), and broadened hysteresis width (ΔH) through the phase transition region. In addition, a decline of the luminous modulation (ΔT˜lum) and solar modulation (ΔT˜sol) efficiencies of the as-prepared films have been determined. Furthermore, compared with the high-quality films reported previously, the electrical conductivity (σ) as a function of temperature (T) reveals reduced conductivity contrast (Δσ) between the insulating and metallic phases of the VO2 films, which was of the order of 2. These outcomes indicated the presence of defects and unrelaxed lattice strain in the films. Further, the comparison of present results with those in the literature from similar works show that the preparation of high-quality films at TS lower than 650 °C presents significant challenges.

Effects of solution-shearing process parameters on charge carrier mobility in green solvent-processed organic field-effect transistors

In this work, we explored the effect of solution-shearing processing parameters, coating speed and substrate temperature, on the electrical properties of solution-processed organic field-effect transistors (OFETs) based on 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10) when green solvents are used. Organic semiconductor thin films were solution-sheared with various coating speeds and substrate temperatures and film morphologies/microstructures were investigated by atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis. Our data demonstrate that crystal growth of Ph-BTBT-C10 molecule is highly affected by the two solution shearing processing parameters and, especially, the OFET devices fabricated with cyclohexanone as green solvent exhibited the charge carrier mobility as high as 5.1 cm2/Vs with optimized processing condition. This work could further provide a guideline for process optimization for fabricating high-performance green solvent-processed OFETs.

Effect of substrate temperature on the growth of Nb3Sn film on Nb by multilayer sputtering

We report on the fabrication of niobium tin (Nb3Sn) films by multilayer sequential sputtering on niobium at substrate temperatures ranging from room temperature to 250 °C. The multilayers were then annealed inside a separate vacuum furnace at 950 °C for 3 h. The material properties of the films were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and transmission electron microscopy. The superconducting properties of the films were studied by four-point probe resistivity measurements from room temperature to below the superconducting critical temperature Tc. The highest film Tc was 17.76 K, obtained when the multilayers were deposited at room temperature. When the deposition temperature was raised to 250 °C, a significant reduction in voids was achieved while the film's Tc was 17.58 K.

Isothermal and non-isothermal spreading of a viscous droplet on a solid surface in total wetting condition

We study the isothermal and non-isothermal spreading of viscous silicone oil droplets on a glass surface in total wetting condition. In particular, the effects of viscosity, impact velocity, and substrate temperature on the spreading dynamics are reported. We employ high-speed photography to record time-varying droplet shapes from the side. An infrared camera maps the temperature distribution on the liquid–gas interface. In the isothermal inertial-capillary or early regime, the initial spreading is driven by inertial forces, and kinetic energy converts into surface energy and gets dissipated by bulk viscosity. The later stage is governed by the balance of surface energy and viscosity dissipation, i.e., capillary–viscous or late regime. The characteristics timescales of the two regimes are obtained using scaling arguments. The measured crossover time from early to late spreading regimes for different cases of impact velocity and viscosity corroborates with a scaling analysis developed in the present work. Measurements confirm the value of exponents of established power-law spreading with time in early and late regimes r∼tn. At a larger substrate temperature, the spreading magnitude is larger for droplets with larger viscosity and is explained by the reduction of viscous dissipation by heating the droplet. However, in the case of non-isothermal spreading of a low viscosity droplet, recoiling after the early spreading reduces the spreading magnitude compared to the isothermal case. We explain the recoiling and spreading rates obtained in different cases. We analyze unsteady heat transfer between the droplet and substrate by combining measurements and a numerical model.

Heating influence on hierarchical structures fabricated by direct laser interference patterning

The combination of direct laser interference patterning (DLIP) with laser-induced periodic surface structures (LIPSS) enables the fabrication of functional surfaces reported for a wide spectrum of materials. The process throughput is usually increased by applying higher average laser powers. However, this causes heat accumulation impacting the roughness and shape of produced surface patterns. Consequently, the effect of substrate temperature on the topography of fabricated features requires detailed investigations. In this study, steel surfaces were structured with line-like patterns by ps-DLIP at 532 nm. To investigate the influence of substrate temperature on the resulting topography, a heating plate was used to adjust the temperature. Heating to 250 ^{circ }C led to a significant reduction of the produced structure depths, from 2.33 to 1.06 µm. The reduction is associated with the appearance of a different LIPSS type, depending on the grain orientation of the substrates and laser-induced superficial oxidation. This study revealed a strong effect of substrate temperature, which is also to be expected when heat accumulation effects arise from processing surfaces at high average laser power.