Increasing Substrate Temperature Research Articles

Effect of substrate temperature on the structural optical and electrical properties of new Cu2Cd0.8Mn0.2SnS4 photo-absorber layer for solar cells

We report for the first time the effect of substrate temperature on the structural, optical, and electrical properties of Cu2Cd0.8Mn0.2SnS4 new photovoltaic absorber layer. Cu2Cd0.8Mn0.2SnS4 thin films were deposited on soda lime glass (SLG) substrates by the spray pyrolysis method at different substrate temperatures. X-ray diffraction measurement revealed the formation of cernyite structure by Cu2Cd0.8Mn0.2SnS4 thin film. Also, an increase in crystal size from 7.23 to 14.35 nm and crystallinity improvement of Cu2Cd0.8Mn0.2SnS4 thin film with an increase in substrate temperature were achieved. The atomic force microscopy indicated an increase in surface roughness with substrate temperature. The elemental composition of the Cu2Cd0.8Mn0.2SnS4 thin films showed Cu-poor, S-poor, and Sn-poor conditions. The optical characterization showed that the absorption coefficient of Cu2Cd0.8Mn0.2SnS4 is in the order of 104 cm−1 and the bandgap decreased from 1.89 to 1.87 eV with an increase in substrate temperature. The refractive index dispersion parameters were discussed in terms of the Wemple-Didomenico and Sellmeier equations. Hall effect measurement indicated that the Cu2Cd0.8Mn0.2SnS4 films exhibit P-type conductivity. High hole mobility and the highest conductivity of 2.77 x104 cm2/Vs and 5.60 (Ω.cm)-1 respectively, were achieved at 400 °C substrate temperature. The Cu2Cd0.8Mn0.2SnS4 deposited at 400 °C is a potential candidate for use as a top absorber layer in the tandem solar cell.

Diffusion and incidence of helium on tungsten surface

In this study, we investigated the diffusion and incidence of helium on tungsten surfaces using first principles and molecular dynamics methods. For three common tungsten surfaces (100, 111, 110), we found that the diffusion barrier of helium is positively/negatively correlated with the interatomic spacing/surface atomic density. The diffusion barriers of helium are relatively similar on the three surfaces, ranging from 5.82 to 6.50 eV. The diffusion barrier of helium on the tungsten surface represents the lower limit of the incidence barrier for helium implantation into tungsten. In our simulation, only helium with an incidence energy greater than 7 eV has the potential to be implanted into tungsten. Generally speaking, the implantation ratio of helium increases with increasing incidence energy and decreases with increasing substrate temperature (although the effect is minor). At a constant temperature, the implantation ratio of helium exhibits an exponential relationship with the incidence energy. The depth distribution of helium can be well described by Gamma distribution function, and the shape and scale parameters of the gamma distribution function can be determined based on the mean and variance of the helium depth distribution. The proposed fitting function allows for the quantitative description of the mean and variance of the helium depth distribution based on the incidence conditions (incident energy E and substrate temperature T), thereby determining the helium depth distribution. This has important implications for the in-depth study of helium-induced tungsten surface fuzz formation.

Temperature evolution of pseudo magnetic properties and vortex state in Fe71Ga29 thin films

We report on the temperature evolution of pseudo magnetic properties and vortex state in Fe71Ga29 thin films at different substrate temperatures (RT-25 °C, 50 °C, 75 °C, and 150 °C) using minor loop analysis and first-order reversal curves respectively. Phase purity of Fe71Ga29 thin films confirmed with grazing incidence X–ray diffraction, which confirms the A2-type disordered phase. The minor loop parameters such as energy loss coefficient WF0 (362 kOe.emu/cc to 278 kOe.emu/cc) and trough depth coefficient WR0 (67.30 kOe.emu/cc to 50.23 kOe.emu/cc) values drop as grain size increases due to a reduction in defects as a result of an increase in substrate temperature. First-order reversal curves allow us to estimate the coercivity variation and switching field distribution that allow us to get information about magnetic interactions between the domains. Additionally, the contour plots of FORC and MFM phase images infer the coexistence of multidomain and Vortex State (VS) in all the Fe71Ga29 thin films deposited at different substrate temperatures.

Optimization of deposition conditions to tune optoelectronic properties of MoO3-x films prepared by RF-sputtering technique

Tunable optoelectronic properties of Molybdenum oxide (MoO3-x) make it a suitable applicant for its use as a catalyst and a hole transport layer. Oxygen vacancies play a vital role in deciding the properties of MoO3-x. In this article, the influence of deposition conditions like substrate temperature and gaseous environment on optoelectronic properties of MoO3-x films are investigated. Increase in substrate temperature have formed oxygen deficient MoO3-x films having lesser transmission (∼30%) and higher conductivity (15-200 Ω−1cm−1). Films prepared at the substrate temperature of 400 °C and rf-power 80 W are mostly crystalline and have led to the formation of MoO2 along with MoO3-x which results in highly conducting less transparent film suitable for catalysis application. Further, introduction of oxygen gas during deposition led to the formation of highly transparent (∼80%) and resistive (10−6 Ω−1cm−1) thin films suitable for hole transport layer application. An increase in oxygen concentration and decrease in oxygen vacancy is confirmed by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy measurement respectively for films deposited in presence of oxygen gas. These studies imply that stoichiometry of molybdenum oxide can be controlled by varying the film preparation conditions and thus optoelectronic properties can be tuned accordingly.

Reactions of NH3 on high-temperature silicon surface and structure evolution during silicon nitride film growth

Temperature and dosage-dependent reactions of NH3 on the Si(111)-(7 × 7) surface have been studied by low-temperature scanning tunneling microscopy. It was found that the surface reaction exhibited three different dissociative adsorption channels as the temperature increases at low exposure. Under the condition of high exposure, the amorphous structure of silicon nitride film gradually transformed into an ordered phase, with the increase of substrate temperature, and finally presented an 8/3 × 8/3 structure. This means that both exposure and temperature are critical for forming an ordered surface structure. Furthermore, many adsorbates were observed on the nitride region during the growth process, which is believed to be the intermediate reactants in the nitridation reaction and consumed in the subsequent annealing process to form an orderly and clean surface morphology.

Scrutinizing the effect of substrate temperature and enhancing the multifunctional attributes of spray deposited copper gallium sulfide (CuGaS2) thin films

ABSTRACT Polycrystalline chalcopyrite CuGaS2 thin films were prepared using a spray pyrolysis route has been considered a potential material for the solar cell absorber layer. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) studied the impact of substrate temperature in the range of 200–300˚C on surface profile and roughness. Powder X-ray diffraction disclosed that the films were polycrystalline at all examined substrate temperatures, with crystallite size increasing with increased substrate temperature. The UV-Vis displays the cut-off wavelength in 550–880 nm for varied substrate temperatures of CuGaS2 thin films, and the observed band gap is 2.75 eV–1.89 eV. The electrical attributes showed the enhancement in mobility (4.632 cm2 V−1 s−1) for varied substrate temperatures of CuGaS2 thin films. The 300˚C temperature sprayed CuGaS2 polycrystalline films are a decent candidate to be apposite as an absorber layer in thin film photovoltaic solar cells.

Effect of Void Defects on the Indentation Behavior of Ni/Ni3Al Crystal.

Inconel 718 (IN 718) superalloys are widely used as engineering materials owing to their superior mechanical performance. And voids are unavoidable defects in IN 718 superalloy preparation, which dramatically affect the mechanical properties of IN 718 superalloys. In this work, the effects of void radius, distance from the top of the void to the substrate surface, and substrate temperature on the mechanical properties of the Ni/Ni3Al crystal are systematically investigated. It is shown that voids affect the formation of stair-rod dislocations and Shockley dislocations in the substrate, which in turn determines the mechanical properties. Thus, with the increase in void radius, Young's modulus and hardness gradually decrease. With the increase in void distance, Young's modulus and hardness increase and finally tend to be stable. In addition, the increase in substrate temperature leads to the interphase boundary becoming irregular and increases the defects in the γ and γ″ phases. As a result, Young's modulus and hardness of the substrate decrease. This work aims to provide a guideline for investigating the indentation properties of Ni-based superalloys using MD.

Adatom controlled emergence of high hardness in biocompatible beta-Ti3Au intermetallic thin film surfaces

There is growing international interest in hard biocompatible thin film surface coatings to extend the lifetime of medical implants. Parameters of the physical vapour deposition technique can be utilized to fine tune the microstructure and resulting properties of the growing thin film surface by modifying the adatom mobility of the incoming species. This work investigates the evolution of high hardness and biocompatibility of sputter deposited beta-Ti3Au intermetallic thin film surfaces as a function of growth temperature and pressure. Titanium and gold are sputtered in an optimised 3:1 ratio over glass and Ti6Al4V substrates at varying pressures of 0.3 to 1.2 Pa and temperatures of 25 to 450°C. The microstructure and crystallinity of the deposited films improved with reduction in pressure from 1.2 to 0.3 Pa but development of the β-Ti3Au intermetallic compound occurred at temperatures above 350˚C. The density of the films also increased with reducing pressure, whereas improvement in their columnar structure was observed with increasing substrate temperature. These microstructural changes caused by adatom mobility variation, led to the emergence of superior mechanical surface hardness, reaching a peak value of 12.5 GPa for films grown at 0.3 Pa and 450°C. All thin film surfaces were highly biocompatible with ion leaching levels below 1 ppm, and films deposited at lower pressure exhibited much safer cytotoxic profiles against L929 mouse fibroblasts. This work demonstrates the emergence of high hardness and biocompatibility in Ti3Au thin film surfaces with potential as next generation medical implant coating materials.

Kinetic Monte Carlo simulation study of the early stages of epitaxial SiC (0001) growth

A kinetic Monte Carlo (kMC) simulation with a cluster-multiple labeling technique was carried out to study the dynamic behavior of Si-C clusters during the early stage of epitaxial growth. In the model, a crystal lattice was established to fix the physical location of atoms and interatomic bonding. Events, such as adatoms adsorption, diffusion on the planar surface, and attachment to and detachment from clusters of adatoms were considered in the model. The Si and C atoms were treated individually to achieve more elaborate information for dynamic behavior of the clusters in the crystal surface. Moreover, a cluster multiple labeling technique, also known as the Hoshen - Kopelman algorithm was used to identify Si-C clusters. Then the properties of the clusters were calculated and analyzed by the algorithm. The simulation results showed that the number of Si-C clusters gradually decreases with increasing substrate temperature and decreasing deposition rate, and that the average size of Si-C clusters at high temperatures is much larger than that at low temperatures. Furthermore, the Si:C ratio on the growing surface has a significant effect on the surface morphology. At Si-rich conditions, the cluster density is relatively high, and the cluster shape is not homogeneously distributed. While with the increase of C mole fraction, the cluster density gradually decreases and the cluster shape becomes more uniform. Therefore, a higher concentration of C in deposition flux is beneficial to the early stage of nucleation. These findings are consistent with predictions for the case of the epitaxial growth of SiC.

Black soldier fly (Diptera: Stratiomyidae) larval heat generation and management.

Mass production of black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae results in massive heat generation, which impacts facility management, waste conversion, and larval production. We tested daily substrate temperatures with different population densities (i.e., 0, 500, 1000, 5000, and 10 000 larvae/pan), different population sizes (i.e., 166, 1000, and 10 000 larvae at a fixed feed ratio) and air temperatures (i.e., 20 and 30 °C) on various production parameters. Impacts of shifting larvae from 30 to 20 °C on either day 9 or 11 were also determined. Larval activity increased substrate temperatures significantly (i.e., at least 10 °C above air temperatures). Low air temperature favored growth with the higher population sizes while high temperature favored growth with low population sizes. The greatest average individual larval weights (e.g., 0.126 and 0.124 g) and feed conversion ratios (e.g., 1.92 and 2.08 g/g) were recorded for either 10 000 larvae reared at 20 °C or 100 larvae reared at 30 °C. Shifting temperatures from high (30 °C) to low (20 °C) in between (∼10-d-old larvae) impacted larval production weights (16% increases) and feed conversion ratios (increased 14%). Facilities should consider the impact of larval density, population size, and air temperature during black soldier fly mass production as these factors impact overall larval production.

Effect of carbon nanotube substrate temperature on the evolution mechanism of microstructure in FeCoNiCrCu coatings

The microstructure and substrate temperature dependence of FeCoNiCrCu high-entropy alloys (HEAs) coatings on carbon nanotube (CNT) surfaces were investigated using experimental and molecular dynamics simulations. It was found that the crystal structure of FeCoNiCrCu underwent the evolution of amorphous, stacking faults (SFs), multiple-fold twins, and columnar grains with an increase in the CNT substrate temperature. When the CNT substrate temperature was less than 800 K, the SFs and microtwin formation was induced by the mismatch stress at the interface of HEAs and CNT. Meanwhile, the refinement of SFs was caused by continuous crossing and cutting of dislocations. When the CNT substrate temperature was greater than 800 K, multiple-fold twin were induced by thermal stress at the surface of HEAs coating. During the evolution of the fivefold twin, the first microtwin was formed from the surface of the HEAs, and the remaining four microtwin growth from the center successively. These results provide a new method to design and control the interface structure between HEAs and CNTs.

Effect of Substrate Temperature on Variations in the Structural and Optical Properties of Cu2O Thin Films Deposited via RF Magnetron Sputtering

In the present study, Cu2O films were deposited on a glass substrate via RF (radio frequency) magnetron sputtering under substrate temperature conditions that ranged from room temperature (RT, 25 °C) to 400 °C. The structural, compositional, and optical properties of the Cu2O films were analyzed in relation to the experimental variables by applying various measurement methods. The substrate temperature was a crucial factor in shaping the structural, compositional, and optical properties of the Cu2O films that were synthesized via RF-magnetron sputtering. Our findings revealed that the Cu2O films exhibited a cubic structure, which was confirmed by XRD analysis. Specifically, the (111) and (200) planes showed different trends with respect to the substrate temperature. The intensity of the (111) peak increased at 250 °C, and above 300 °C, the preferred orientation of the (111) plane was maintained. The grain size, which was determined via FE-SEM, displayed a positive correlation with the substrate temperature. Additionally, XPS analysis revealed that the binding energy (BE) of the Cu2O film sputtered at 400 °C was similar to that which was previously reported. Notably, the as-grown Cu2O film demonstrated the highest transmittance (15.9%) in the visible region, which decreased with increasing substrate temperature. Furthermore, the energy band gap (Eg) of the Cu2O films remained constant (2.51 eV) at low substrate temperatures (25 °C to 200 °C) but exhibited a slight increase at higher temperatures, reaching 2.57 eV at 400 °C.

The Effect of Deposition Temperature on Ba<sub>0.8</sub>Sr<sub>0.2</sub>TiO<sub>3</sub> Films Prepared by Pulsed Laser Deposition Technique

Barium strontium titanate (Ba0.8Sr0.2TiO3) thin films have been prepared by pulsed laser deposition (PLD). The thin film of (Ba0.8Sr0.2TiO3) was deposited on a silicon (Si) substrate with different deposition temperatures. The XRD pattern identifies these specimens as being of the tetragonal phase. As the deposition substrate temperature varied from 200 °C to 400 °C, the average crystal size of BST increased from 34 nm to 68 nm calculated by the XDR pattern. Field (FESEM) images have estimated the particle size of the film. The dielectric constant increased with increasing substrate temperature.

Substrate temperature dependence of microstructure and magnetoresistance field sensitivity of Co–ZnO non-uniform nanocomposite film

Co–ZnO metal-semiconductor nanocomposite films have drawn a growing number of attention due to their significant room temperature (RT) magnetoresistance (MR) effect. In this paper, Co–ZnO non-uniform nanocomposite films with high crystallinity of ZnO matrix have been prepared by controlling substrate temperature. With the increase of substrate temperature, the Co particles grow and gradually aggregated into ferromagnetic clusters, which leads to an increase in saturation magnetization (Ms) from 5.8 to 6.7 kGs. Moreover, the growth of ferromagnetic clusters results in the formation of cluster-particle current paths and isolated magnetic particles, which have less contribution to the MR, causing the separation between MR curve and -(M/Ms)2 curve. This phenomenon induces a broadening of the MR curve, which modulates the shift of the MR field sensitivity (FS) peak toward higher fields. When the substrate temperature is 250 °C, high ZnO matrix crystallinity, -MR value (2.6%) and effective modulation of MR FS in Co–ZnO non-uniform nanocomposite films can be achieved simultaneously. It provides a reference for the application and modification of Co–ZnO MR devices.

High-quality thin film growth of the weak topological insulator BiSe on Si (111) substrates via pulsed laser deposition

In this work, we report the growth of high-quality BiSe thin films deposited on Si (111) substrates at different temperatures via pulsed laser deposition. We observe poor sample quality at a low substrate temperature (Tsub=175°C), and as the substrate temperature increases, the crystallinity of the samples increases. At a substrate temperature, Tsub=250°C, BiSe Raman modes (modes centered around 97.6 and 112.9 cm−1) start to emerge with less intensity and evolve with the increase in the substrate temperature and at Tsub=325°C closely match with that of single crystals. These modes correspond to the vibrations of Se-atoms from the Bi2Se3 quintuple layers and Bi-atoms from the Bi-bilayer. By carefully investigating the structural properties and the Raman modes of BiSe thin films at each substrate temperature, we provide an optimal condition to grow high-quality thin films of BiSe by pulsed laser deposition.

Resistivity minima in disordered Co2FeAl0.5Si0.5 Heusler alloy thin films

An exhaustive study of the effect of anti-site disorder on the ‘zero-field’, ρ(T, H = 0), and ‘in-field’, ρ(T, H = 80 kOe), electrical resistivity in 50 nm thick Co2FeAl0.5Si0.5 (CFAS) Heusler alloy thin films (deposited on the Si(100) or SiO2/Si(100) substrates at fixed substrate temperatures in the range 27°C≤TS≤550°C), has been carried out. Irrespective of the strength of disorder, resistivity goes through a minimum as a function of temperature at T = Tmin. With increasing substrate temperature, the crystalline order of the CFAS thin films improves so much so that the films deposited at 500 °C have the lowest anti-site disorder within the B2 structure and the least residual resistivity. A quantitative comparison of our results with the predictions of the existing theoretical models permits us to unambiguously identify the diffusive and ballistic transport mechanisms, responsible for ρ(T, H = 0) and ρ(T, H = 80 kOe) in different temperature ranges and accurately determine their relative magnitudes. The electron-diffuson (e – d) scattering and weak localization (WL) mechanisms, responsible for negative temperature coefficient of resistivity (TCR) for T < Tmin, compete with the positive TCR mechanisms, electron-magnon (e – m) and electron–phonon (e – p) scattering, to produce the resistivity minimum at Tmin. The e – d and WL contributions to ρ, ρe-d and ρwl, dominate over the e – m and e – p contributions, ρe-m and ρe-p, for T<Tmin whereas the reverse is true for T>Tmin. At any given temperature, ρe-d, ρwl and ρe-m decrease while ρe-p increases as the atomic order improves with increasing substrate temperature, TS. ρe-p and ρe-m originate from the phonon-induced non-spin-flip two-band (s↑↓- d↑↓) scattering and magnon - induced spin-flip s - d interband (s↑↓- d↓↑) transitions, respectively. In all the CFAS films, except for the one deposited at TS = 27°C, the thermal renormalization of the spin-wave stiffness, due to the electron - magnon interaction, contributes significantly to ρe-m(T). Furthermore, we demonstrate that the negative magnetoresistance (MR) is a consequence of a progressive suppression of the WL effect and e – m scattering by external magnetic field. However, the WL contribution to MR turns out to be negligibly small as the e – m contribution almost entirely accounts for MR over the temperature range 5K≤T≤300K.

Density of amorphous sputtered Ge2Sb2Te5 thin films

The density, crystallinity, and microstructure of reactively sputtered amorphous Ge2Sb2Te5 thin films have been assessed as a function of deposition temperature. The continuous density increase was observed with increasing substrate temperature between room temperature and 200 °C. The films deposited at room temperature are amorphous and exhibit a columnar structure with a lateral size of cells in the 10–15 nm range. Cells consist of high-density interior with boundaries with the density lower by ∼9% due to incorporation of pores. The pores and the columnar microstructure can be eliminated by deposition at 80 °C while still preserving the amorphous phase. The density of pore- and stress-free amorphous Ge2Sb2Te5 is 6.16 g/cm3 and is only 1.5% lower than the crystalline Ge2Sb2Te5 with NaCl structure.

Влияние размерного эффекта на проводимость наночастиц NiO плазмохимического синтеза

Nickel oxide nanoparticles were obtained by condensation from a vacuum arc discharge plasma and subsequent deposition on a substrate at various temperatures (300–700 K). The samples were characterized using X-ray diffraction and transmission electron microscopy. The formation of a phase of stoichiometric NiO, whose crystallite size increases with increasing substrate temperature, is confirmed. Electrophysical properties are investigated by measuring DC and AC conductivity and dielectric properties as a function of temperature. The frequency and temperature dependences of the dielectric permittivity and conductivity in alternating current demonstrate the behavior characteristic of dielectrics with a predominance of charge carriers.

Nanoscale surface dynamics of RF-magnetron sputtered CrCoCuFeNi high entropy alloy thin films

High entropy alloy (HEA) thin films of CrCoCuFeNi are grown on stainless steel substrate using radiofrequency (RF) magnetron sputtering method at different sputtering times (30, 60 and 90 minutes), substrate temperatures (room temperature, 100 and 200 deg. Celsius) and RF powers (100, 150 and 200 W). The nanoscale morphology and topography of the thin films are obtained using an atomic force microscopy (AFM) method. The average surface roughness, interface width, fractal and multifractal characteristics of the films are presented. It is shown that the average surface roughness and interface width decrease with the time of deposition while considering the combination of the other factors. The autocorrelation and height-height correlation functions reveal that these surfaces are self-affine and exhibit fractal characteristics. The increase in sputtering power, with different combinations of time and temperature, is related to large fractal dimension and small lacunarity coefficient. The increase in substrate temperature (for different combinations with time and RF power) is shown to enhance the spatial roughness of the HEA thin films. A multifractal analysis undertaken using generalized fractal dimension, mass exponent against moment order and multifractal spectrum reveal that all the films have a multifractal character; and the films deposited at high temperatures and powers exhibit the strongest multifractal behaviour.

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.