Change In Substrate Temperature Research Articles

Effect of substrate temperature on the microstructural and optical properties of RF sputtered grown ZnO thin films

This study investigates the effect of substrate temperature ranging from 30 0C to 150 0C on micro-structural and optical properties of ZnO thin films. RF sputtering method is used for the deposition of thin films on p- type Si substrate. The X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) study is used for the investigation of different micro-structural and surface morphological properties of ZnO thin films. XRD results portrays hexagonal wurtzite structure, indices (0 0 2) preferred orientation thin films. UV–VIS-NIR spectroscopy and photoluminescence spectroscopy are employed to find the optical parameters of deposited ZnO thin films. It has been observed that the deposited thin films are highly transparent with the transmittance greater than 85% and their refractive index varying from1.75 to 2.75 as the substrate temperature changes from 30 0C to 150 0C. Various optical parameters like transmittance (T), absorption (A) and their outcomes are also examined and reported. The optical band gap shows a marginal variation from 3.22 eV to 3.26 eV.

Are lizards sensitive to anomalous seasonal temperatures? Long-term thermobiological variability in a subtropical species.

Alterations in thermal niches have been widely associated with the Anthropocene erosion of reptiles’ diversity. They entail potential physiological constraints for organisms’ performance, which can lead to activity restrictions and impact fitness and demography. Reptiles are ectotherms which rely on seasonal periodicity to maximize the performance of biological functions. Despite it, the ecological implications of shifts in local temperatures are barely explored at the seasonal scale. This study aims to assess how changes in air temperature and substrate temperature affect the activity, body temperature (Tb) and thermoregulation patterns of the sand lizard, Liolaemus arambarensis (an endangered, microendemic species from southern Brazil), throughout a four-year period. Field surveys were conducted monthly on a restricted population in a sand-dune habitat. The annual fluctuations of the seasonal temperatures led to significant changes in the activity and Tb of L. arambarensis and shaped thermoregulation trends, suggesting biological plasticity as a key factor in the face of such variability. Lizards tended to maintain seasonal Tb in mild and harsh seasons through increased warming/cooling efforts. Anomalous winter conditions seemed especially critical for individual performance due to their apparent high impact favouring/constraining activity. Activity and thermoregulation were inhibited in frigid winters, probably due to a vulnerable physiology to intense cold spells determined by higher preferred body temperatures than Tb. Our results warn of a complex sensitivity in lizards to anomalous seasonal temperatures, which are potentially enhanced by climate change. The current work highlights the importance of multiannual biomonitoring to disentangle long-term responses in the thermal biology of reptiles and, thereby, to integrate conservation needs in the scope of global change.

Substrate temperature dependent physical properties of SnS1−xSex thin films

Recently, researchers showed great interest on SnS1−xSex alloy films because of their tunable physical properties that are suitable as an absorber layer in thin film solar cells. In the present work, SnS1−xSex thin films were deposited by thermal co-evaporation of SnS and Se at different substrate temperatures ranging from 200 to 350 °C. The influence of substrate temperature (Ts) on composition, structure, surface morphology, topography and optical properties of as-deposited films was investigated using appropriate techniques and the results are reported in detail. The EDS analysis of SnS1−xSex films showed that Sn/(S + Se) ratio was changed from 0.84 to 1.16 with increase of substrate temperature. All the films were polycrystalline in nature, exhibiting (111) plane as preferred orientation with orthorhombic crystal structure. From W–H analysis, the crystallite size and lattice strain in the films were evaluated, where the crystallite size varied in the range, 9–22 nm with substrate temperature. The layers showed a change in the shape of grains with the rise of substrate temperature, where the grain size has increased with Ts. The topographical results indicated an indirect relation between surface roughness and average grain size with change in substrate temperature. The band gap energy values of the films was decreased with increase of Ts and varied in the range, 1.59–1.46 eV. In addition, the photoconductivity measurements revealed that the as-deposited SnS1−xSex films had bimolecular type recombination (γ ~ 0.5) of photo-generated charge carriers.

Detailed Structural and Morphological Characterization of InGaN Thin Films Grown by RF Magnetron Sputtering with Various Substrate Temperature

Indium Gallium Nitride thin film was successfully grown on the substrate using an RF magnetron sputter under condition of different substrate temperatures. Various experimental measurements were taken to understand effect of substrate temperature on the structure of thin film and results were analyzed. Grazing mode of XRD results confirmed that thin film has a hexagonal structure with plane for and substrate temperature. It was seen that structural parameters of thin film show a change with substrate temperature change. Reasons were discussed. Strain and stress values in thin film were calculated from experimental results and it was found that all thin film has compressive stress. Morphological parameters of thin film were measured by AFM and it was understood that these properties are varied by changing substrate temperature. Also, growth mode of some thin film was found to be layer-plus-island mode (Stranski-Krastanov growth mode), others was found to be layer by layer growth mode (Frank van der Merwe mode). SEM analysis gives that increasing substrate temperature worsened the surface structure of thin film; it is compatible with and supports XRD results. Compositional values in thin film were found from XPS analysis. In addition to our material, carbon and oxygen have also been obtained from XPS results, as expected. Detailed structural and morphological properties of thin film have been seen to change by changing substrate temperature and we believe this may play an important role in the production of based optoelectronic devices.

Effect of substrate temperature on surface morphology and optical properties of sputter deposited nanocrystalline nickel oxide films

Reactive magnetron sputtering deposition of nickel oxide (NiO) films were done on p-type silicon substrate and glass substrate under Ar+O2 gas environment at substrate temperature of 26 °C, 100 °C, 200 °C and 300 °C. The phase, crystallinity and grain size were analysed by x-ray diffraction in grazing incidence mode (GIXRD). The average grain size varied in the range of 12 nm to 28 nm for NiO films. The microstructural analysis was carried out under a field emission scanning electron microscopy (FESEM) as well as transmission electron microscopy (TEM). Uniform distribution of grains and lower surface roughness were observed for the NiO films processed at relatively higher temperature. Direct band gap of investigated NiO films were measured with the help of absorption data obtained from UV-visible photospectrometer. The direct band gap was found to vary from ≈2.92 eV to ≈3.96 eV with change in substrate temperature.

Substrate temperature compensation for microbolometric focal plane array without TEC

For a normal microbolometric focal plane array, the microbolometric infrared responsivity varies with its substrate temperature fluctuations because of the semiconductor characteristics of the microbolometer array. The relationship between the microbolometric infrared responsivity and substrate temperature is theoretically discussed in this paper. Above the discussion, a new substrate temperature compensation method is proposed for microbolometric focal plane array without TEC. The microbolometric focal plane array is based on a kind of high-speed CMOS readout integrated circuit, of which the microbolometric infrared response voltage signal can be directly read out without infrared response current integration. The bias current for the microbolometer with the proposed substrate temperature compensation method can be adjusted according to the substrate temperature change to achieve a steady microbolometric infrared responsivity. This kind of substrate temperature compensation method is theoretically strict and has been experimentally verified in our laboratory, which is potential for future high-speed, lower-power and small-pixel microbolometric focal plane array.

Effect of substrate temperature on the material properties of the Y2SiO5: Ce3+ thin film by pulsed laser deposition (PLD) method

The effect of substrate temperature on the material properties Y2SiO5: Ce3 + thin film deposited by the pulsed laser deposition method reported. The deposition temperatures used are room temperature, 150, 250, 350, 450 and 6000 C. XRD analysis shows that the average crystallite size is about 1.66 nm. The material is monoclinic in structure with the most prominent diffraction peak at 29.20. An increment in surface thickness was observed as the deposition temperature increases from 150 to 450° C and decreases from 450 to 600° C. The decrease in surface thickness ascribes to a reduci.tion in deposition rate. The main photoluminescence (PL) emission peak was observed at 465 nm, which is attributed to the electronic transition from 5d → 4f of the Ce3+orbitals. The excitation peak was detected at 337 nm, which can be attributed to the transition of an electron from the ground state (2F5/2) to the excited state (5d) of Ce3+. The highest emission intensity occurs with an excitation wavelength of 337 nm for all deposition temperatures. The maximum decay time was observed at a deposition temperature of 4500 C. The CIE was deployed at an emission wavelength of 465 nm, and the blue color is the corresponding color. The maximum ultraviolet-visible spectrum (UV–vis) absorbance was observed at around 337 nm. The scanning electron microscope (SEM) images show that, the morphology changes as the substrate temperature changes. The Energy Dispersive X-ray Spectrometer (EDS) shows the presence of all the elements of the compound matrix (Y, Si, O, and Ce) with their respective atomic weights.

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.

Size-dependent vibration analysis of carbon nanotubes

Abstract

Effect of substrate temperature on structural and magnetic properties of c-axis oriented spinel ferrite Ni0.65Zn0.35Fe2O4 (NZFO) thin films

Varying the substrate temperature changes structural and magnetic properties of spinel ferrite Ni0.65Zn0.35Fe2O4 (NZFO) thin films. X-ray diffraction of films grown at different temperature display only (004) reflections, without any secondary peaks, showing growth orientation along the c-axis. We find an increase in crystalline quality of these thin films with the rise of substrate temperature. The surface topography of thin films grown at different growth temperatures reveal that these films are smooth with low roughness; however, the thin films grown at 800 °C exhibit lowest average and root mean square (rms) roughness among all thin films. We find iron and nickel to be more oxidized (greater Fe3+ and Ni3+ content) in films grown and annealed at 700 °C and 800 °C, compared to those films grown at lower temperatures. The magnetic moment is observed to increase with an increase of substrate temperature and all thin films possess high saturation magnetization and low coercive field at room temperature. Films grown at 800 °C exhibit a ferrimagnetic–paramagnetic phase transition well above room temperature. The observed large magnetizations with soft magnetic behavior in NZFO thin films above room temperature suggest potential applications in memory, spintronics, and multifunctional devices.

Effect of Substrate Temperature on Aluminium Thin Films Prepared byRF-Magnetron Sputtering

Pure aluminium thin films were sputtered on steel substrates at 40°C, 60°C, 80°C and 100°C substrate temperatures through rf magnetron sputtering. Microstructural and topographical characterizations were undertaken through SEM, AFM and XRD techniques. SEM imaging revealed considerable microstructural evolution with change in substrate temperature. The morphology of the films consisted of coherent long columns extending from one edge to the other of the substrate surface with terraces between adjacent structures. Thetopographical dependence of the thin films with changes in substrate temperature was studied by AFM. As the temperature increased, the surface structures gradually interconnected resulting in reduction of terraces. Quantitative AFM analysis further revealed that increase in temperature, decreases the root mean square roughness, decrease in valleys and PSD correlation length.The XRD pattern at 80°C and 100°C revealed slight influence of these temperatures on the crystallinity of the aluminium thin films.

Ultra-compact and temperature-insensitive Mach-Zehnder interferometer based on one multimode waveguide on silicon.

An ultra-compact and temperature-insensitive Mach-Zehnder interferometer device is introduced on the silicon-on-insulator platform. The device is constructed through one straight multimode waveguide, which consists of two densely packed silicon wires with a narrow gap of varying positions along the device. The total width of the proposed Mach-Zehnder interferometer is only about 1 μm. Interference patterns with extinction ratios of better than 20 dB are achieved. Temperature insensitive operation of the proposed device is also demonstrated for both global and local temperature changes. The shift rate of the wavelength response with respect to the substrate temperature change is within ±10 pm/K in a 30 nm wavelength range.

Physical Properties of Spray Deposited Fe:ZnOThin Films

Iron doped zinc oxide (Fe:ZnO) thin films were prepared on glass substrates using wet chemical process, spray pyrolysis by varying the substrate temperature (TS) in the range 300 - 450°C at a constant Fe-doping concentration of 2 at. %. The physical properties of as prepared Fe:ZnO films were investigated using various techniques. The XRD studies indicated polycrystalline nature with the (101) plane as dominant orientation and the layers exhibited the hexagonal wurtzite crystal structure. The SEM micrographs revealed uniform growth of spherical grains over the substrate surface and the EDS profiles confirm the presence of Zn, O and Fe elements in all the films. The FTIR spectra revealed that the existence of Zn-O stretching vibrational mode at 531cm-1 as a dominant mode in the films. Further the optical transmittance and reflectance properties were studied by UV-Vis-NIR spectrophotometer. The optical band gaps are computed from the differential reflectance (dR/dλ) spectra. The band gap values were varied with the change of substrate temperature in the range, 3.20 – 3.70 eV.

STRUCTURE AND PHOTO- FUNCTIONAL PROPERTIES OF TiO2 THIN FILM PREPARED BY RF HELICON MAGNETRON SPUTTERING

Fabrication of titanium dioxide (TiO2) thin film (200nm) has been done by using RF helicon magnetron sputtering from metallic Ti target under changing of O2 flow rate and substrate temperature. Film structure was measured by X-ray diffraction (XRD). The films were examined by an X-ray photoelectron spectroscopy (XPS) to study the structure; atomic force microscopy (AFM) and field-emission scanning electron microscope (FE-SEM) were employed to investigate the surface morphology and the cross section of films, respectively. Optical properties and optical band gap were calculated by using UV-VIS spectrophotometer. Photocatalytic activity was evaluated by light induced degradation of methylene blue (MB) solution using UV and Vis light. TiO2 thin film with a rutile phase at substrate temperature 100oC and O2 flow rate to 0.5 - 1.0sccm can be obtained, also an anatase phase can be fabricated when set substrate temperature to 300 oC and O2 flow rate to 2.5sccm. Obtained films showed a high dense with smooth surface and high crystalline. Maximum degradation rate (about 85%) of MB has been indicated at anatase phase under UV light irradiation, while under Vis light irradiation rutile and anatase mixture phase showed a maximum degradation rate (about 15%). In this work, the morphological, structural, optical, and photocatalytic properties of TiO2 thin films that were fabricated by RF helicon magnetron sputtering under change of O2 flow rate and substrate temperature have been investigated. It is expected that the change of substrate temperature and/or O2 flow rate will make ability to control the film structure.

Growth of Cd1-xZnxTe thin films with high Zn content by close-spaced sublimation

The Cd1-xZnxTe films with a high x value of about 0.42 were achieved by close-spaced sublimation (CSS) method using a pre-alloyed CdZnTe source on the basis of two critical growth factors. A relatively high growth temperature is one of two key factors to achieve high Zn content in CdZnTe films. The x value of Cd1-xZnxTe varies from 0.10 to 0.42 as the substrate temperature changes from 100 to 500 °C under the pressure of 10 Pa. Moreover, it can be inferred that the sticking coefficient ratio of Zn to Cd is about 2.5–4 times at 500 °C than that at 400 °C. The other factor, more importantly, is the growth pressure, which should be below 10 Pa, while a high pressure of above 1000 Pa generally adopted in the Cd1-xZnxTe films using the CSS method always leads to Cd1-xZnxTe films with a low x value. The sudden increase of Zn vapor pressure under a growth pressure lower than 10 Pa is responsible for a high Zn content in the Cd1-xZnxTe films.

Sandwich heterostructures of antimony trioxide and bismuth trioxide films: Structural, morphological and optical analysis

Thin film heterostructures can be advantageous since they either exhibit novel or a combination of the properties of their components. Here we propose sandwich-type of heterostructures made of antimony trioxide and bismuth trioxide thin films, which were deposited on glass substrates by thermal vacuum deposition at three substrate temperatures, 50°Celsius apart. Their morphology and optical properties are studied as compared to the corresponding monolayers. It was found that even small substrate temperature changes strongly influence their morphology, increasing their roughness, while the optical transmittance shows a slight decrease as compared with the individual layers. The corresponding absorption coefficient exhibits intermediate values as compared to the component oxides, while the energy bandgaps for the indirect allowed transitions move towards the Infrared when overlapping the antimony and bismuth trioxides.

Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation.

This work demonstrates a method to prepare homogeneous distributions of analytes to improve data reproducibility in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Natural-air drying processes normally result in unwanted heterogeneous spatial distributions of analytes in MALDI crystals and make quantitative analysis difficult. This study demonstrates that inducing Marangoni flows within drying droplets can significantly reduce the heterogeneity problem. The Marangoni flows are accelerated by changing substrate temperatures to create temperature gradients across droplets. Such hydrodynamic flows are analyzed semi-empirically. Using imaging mass spectrometry, changes of heterogeneity of molecules with the change of substrate temperature during drying processes are demonstrated. The observed heterogeneities of the biomolecules reduce as predicted Marangoni velocities increase. In comparison to conventional methods, drying droplets on a 5 °C substrate while keeping the surroundings at ambient conditions typically reduces the heterogeneity of biomolecular ions by 65%-80%. The observation suggests that decreasing substrate temperature during droplet drying processes is a simple and effective means to reduce analyte heterogeneity for quantitative applications. Graphical Abstract ᅟ.

スパッタ薄膜の内部応力に及ぼす基板温度の影響

In our recent research, it was found that the effects of ion bombardment for thin films can be estimated using the ion bombardment parameter Pi. Internal stress in sputtered thin films can be classified into thermal stress and true stress. In this study, the internal stress in thin films was evaluated by the changes in evaporant sources (Ni or Al), substrate (Si or glass), and substrate temperature during the deposition. Internal stress in thin films with ion bombardment as a part of true stress was controlled by plasma diagnostics. Thermal stress in the thin films was evaluated from the thermal expansion coefficient of the films and the substrate with the changing substrate temperature during thin film deposition. It was found that internal stress of the films was strongly dependent on thermal stress. Despite the control of ion bombardment by plasma diagnostics, the values of true stress for the films were not continuous. This suggests that in addition to ion bombardment, true stress is also governed by microstructural changes with changing substrate temperature.

Nonlinear optical parameters of nanocrystalline AZO thin film measured at different substrate temperatures

The 2.2wt% of aluminum (Al)-doped zinc oxide (AZO) transparent and preferential c-axis oriented thin films were prepared by using radio frequency (DC/RF) magnetron sputtering at different substrate temperature ranging from room temperature to 200°C. For structural analysis, X-ray Diffraction (XRD) and Atomic Force Electron Microscope (AFM) was used for morphological studies. The optical parameters such as, optical energy gap, refractive index, extinction coefficient, dielectric loss, tangent loss, first and third order nonlinear optical properties of transparent films were investigated. High transmittance above 90% and highly homogeneous surface were observed in all samples. The substrate temperature plays an important role to get the best transparent conductive oxide thin films. The substrate temperature at 150°C showed the growth of highly transparent AZO thin film. Energy gap increased with the increased in substrate temperature of Al doped thin films. Dielectric constant and loss were found to be photon energy dependent with substrate temperature. The change in substrate temperature of Al doped thin films also affect the non-liner optical properties of thin films. The value of χ(3) was found to be changed with the grain size of the thin films that directly affected by the substrate temperature of the pure and Al doped ZnO thin films.

The influence of substrate temperature on the optical and micro structural properties of cerium oxide thin films deposited by RF sputtering

In this investigation, CeO2 thin films were deposited on glass substrates with different substrate temperatures by using RF Magnetron sputtering technique. The deposited films were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, room temperature photoluminescence spectroscopy, micro-Raman and X-ray photoelectron spectroscopy. The thicknesses of the film were determined by using profilometer and it was varied from 0.70μm to 0.87μm. From the XRD results, it is evident that the film deposited at room temperature (RT) is amorphous in nature. The remarkable change in character from amorphous to crystalline is observed by increasing the substrate temperature from RT to 300°C, and the crystallites were found to be in cubic phase with preferred orientation along (220). Calculated crystallite sizes were in the range of ∼8.6nm. Optical characteristics were studied as a function of change in substrate temperature and thickness in air. Overall transmittance percentages of the films (85–60%) were found to decrease with increase in substrate temperatures. The results show that the energy band gap was found to be decreased (3.95–3.75eV) with the increase of substrate temperature as well as thickness of the film. Optical constants like refractive index (n), extinction coefficient (k), optical conductivity (σ), real and imaginary part of dielectric constant (ε1 &ε2), volume energy loss function (VELF) and surface energy loss function (SELF) were evaluated by using UV spectra. It is found from PL spectra that the decreased defects for the films prepared at a higher substrate temperature. A strong near band edge emission and weak green emission were observed at ∼360 and ∼519nm respectively. The micro-Raman results show the characteristic peak of CeO2F2g at ∼465cm−1. It is found from the spectrum that the peak intensity of the films increased with increase in substrate temperature. XPS analysis confirms the highly non-stoichiometric nature of the films with dominant occurrence of Ce4+ (CeO2) and subsidiary occurrence of Ce3+ (Ce2O3).