Varying Substrate Temperature Research Articles

Synthesis of single-phase stoichiometric InTe thin films for opto-electronic applications

Abstract Mono-phased and stoichiometric InTe thin films were successfully prepared using vacuum evaporation technique. A systematic variation in substrate temperature and annealing temperature along with annealing duration resulted stoichiometric and single phase InTe films. The annealing treatment of as-deposited films resulted in the structural transformation from mixed phase of In2Te3 and InTe to mono-phased InTe. The electrical conductivity of stoichiometric single phase films was found to be 15.612 Ω−1 cm−1. The optical band gap of stoichiometric InTe films was found to be 1.42 eV and absorption coefficient of the films was of the order of 106 cm−1. Electrical properties of mono-phased films accompanied with optical properties such as direct band gap and absorption coefficient makes them suitable for optoelectronic devices.

Influence of substrate and substrate temperature on the structural, optical and surface properties of InGaN thin films prepared by RFMS method

In this work, the pure InGaN thin films were grown using n-type and p-type silicon substrates at varying substrate temperatures using the sputtering method. The effects of substrate and substrate temperature on the structural, morphological and optical properties of the thin films grown were investigated. X-ray diffraction (XRD) analyzes of the obtained films illustrates crystal structures at 500̊ C substrate temperature, the films were found to be hexagonal. Scanning electron microscopy (SEM) was used to investigate the shape, size and surface distribution of the particles formed on film surfaces. The reflection and optical band gap (Eg) of the films were investigated from the optical analyzes taken with the UV-VIS spectrophotometer. As a result of these analyzes, it has been reached that the substrate and substrate temperature have a great influence on the structural, morphological and optical properties of the films. The experimental findings obtained in the study are compared with the studies given in the literature and the similarities and differences are discussed.

Variation of Distribution of Concentration of Implanted Impurity with into Account Mismatch-Induced Stresses under Influence of Variation of Substrate Temperature

Variation of Distribution of Concentration of Implanted Impurity with into Account Mismatch-Induced Stresses under Influence of Variation of Substrate Temperature

Nanostructured and mechanical properties of high-entropy alloy nitride films prepared by magnetron sputtering at different substrate temperatures

ABSTRACT(AlCrNbSiTiV)N high-entropy alloy (HEA) nitride coatings have been grown on cermet tools inserts and glass substrates. Using reactive direct current magnetron sputtering with an equimolar AlCrNbSiTiV HEA target and Ar plasma and N2 reactive gases. In this study, the influence of (AlCrNbSiTiV)N coatings varied substrate temperature (room, 100, 200, 300, 400°C), on the structure, mechanical properties and cutting performance of the cermet cutting tools was investigated in dry machining of a SCM440 steel. The (AlCrNbSiTiV)N films coated was homogeneous, very compact and shows good adhesion strength (classified as HF1). The TEM image results indicate that the (AlCrNbSiTiV)N films are simple face-centre-cubic structures. As the substrate temperature increases, the films hardness increases, reaching the maximum value of 2493 HV at 100°C, and then decreases with further increase in the substrate temperature. The cutting performance improves when coated tools are used. The machined surface with the coated tool using a substrate temperature 100°C deposition parameters, show less surface defects and the tool flank wear is reduced.

Influence of sputtering parameters on the main characteristics of ultra-thin vanadium nitride films

We researched the relation between deposition and ultra-thin VN films parameters. To conduct the experimental study we varied substrate temperature, Ar and N2 partial pressures and deposition rate. The study allowed us to obtain the films with close to the bulk values transition temperatures and implement such samples in order to fabricate superconducting single-photon detectors.

Effect of Annealing Temperature of Cugao2 thin Films by Using RF Magnetron Sputtering Technique on Optical and Structural Properties

Cu-based conductive oxide such as CuGaO2 is seen to be a promising transparent p-type oxide material. The study of p-type semiconductor CuGaO2 thin films have been carried out to investigate the effects of different parameters in providing the optimum result in achieving good optical transparency and conductivity of the thin film. The CuGaO2 thin films were fabricated on quartz substrate via the Radio Frequency (RF) magnetron sputtering technique with varying substrate temperatures and different annealing temperatures. The p-type thin films were deposited at a temperature ranging from room temperature, 100°C, 200°C and 300°C. The samples were also annealed varying from temperature of 500°C, 600°C, 700°C and 800°C. The fabricated sample were characterized using X-ray diffraction (XRD), UV-Visible spectroscopy, and atomic force microscope (afm). XRD showed a peak at 2θ = 36.10° (012). The optical transparency values achieved from UV-Vis spectrometer were seen to be approximately 80% and the bandgaps were found to be in the range of 3.34-3.43 eV which is in line with the bandgap value from the research on CuGaO2 thin films. From the afm, the mean surface roughness increases with increasing temperature and this is due to the increment of grain size. The highest grain size was observed at substrate temperature of 200°C.

Moisture gradients form a vapor cycle within the viscous boundary layer as an organizing principle to worker termites

Studies of termite mound building have considered the mud they prepare, its properties and its composition. Here we consider the behaviors of the mound building termites Macrotermes michaelseni, (Sjostedt), in the presence of the viscous boundary layer (VBL), which spontaneously forms over any surface that air passes over. We looked how soil moisture and air vapor are coupled to form a feedback loop and a spatiotemporal precursor to worker termites in the presence of mound material. We explored residency and activities of workers when presented with a VBL and either varying substrate temperature gradients or a soil moisture transition within the soil substrate. We report the emergence of a ‘vapor conveyor’, which forms around a neutral evaporative equilibrium point (NEEP) at the soil/air interface, where the soil-borne moisture temperature (along the gradient) and the 100% saturated air-borne vapor temperature coincide within the VBL, forming a bubble of neutral mass transfer which, we propose, worker termites are sensitive to as viscosity changes within. We found, on average, that 67% (std. dev 27%) of behavioral events (clustering, excavation, and deposition) occurred within 1 °C either side of the NEEP. We found negative correlation (− 0.78) between the substrate temperature gradient (0.1–0.9 °C mm−1) and the extents of behavioral activity, suggesting coupling between soil-borne moisture and air-borne vapor advection within the VBL. We recorded unique behaviors relating to interaction with the viscosity of vapor-saturated air at this scale. We speculate that workers may exploit the VBL to overcome a classic trade-off, i.e., how to push activities forward into potentially desiccating environments while conserving moisture in both the termites and the soil they build with.

Influence of substrate annealing on inducing Ti3+ and oxygen vacancy in TiO2 thin films deposited via RF magnetron sputtering

Nano-crystalline TiO2 has been prepared by RF magnetron sputtering at varied substrate temperatures ranging from 200 to 500 °C. The alteration of oxygen and titanium atom in TiO2 at uppermost surface is clearly observed on the effect of annealing temperature by Auger Electron Spectroscopy (AES) technique. The measurement of peak to peak value of Ti and O transition line at 400 °C indicates the surface chemical state of O2 in TiO2 thin films defect at surface and Fermi level was analyzed using the X-Ray Photoelectron Spectroscopy (XPS). The Ti 2p observation of pre and post surface treatment shows the concentration of Ti3+ is seven times higher after post sputtered for sample 200 °C. Ti3+ decrease by increasing temperature. The Ti3+-oxygen vacancy which also assigned as Ti2O3 occurred in all sample, yet sample deposited at 400 °C gives nearest binding energy for Ti2O3. This observation also supported by The Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analysis which shows highest total ion count for positive polarity is O+ for sample at 300 °C and Ti ion dominant is Ti2O3+ for sample at 400 °C. Based on the analyses, it is clearly seen that high defect of Ti3+-oxygen vacancy which is located between surface layer and fermi level state, this defect levels was created at surface layer at low annealing temperature. However, increasing temperature leads to defect creation on bellow surface layer which consider as within fermi level layer.

Substrate temperature effect on the crystal growth and optoelectronic properties of sprayed α-Fe2O3 thin films: application to gas sensor and novel photovoltaic solar cell structure

ABSTRACT Iron oxide (Fe2O3) thin films were deposited on glass substrate by varying substrate temperature (Ts) from 300 to 450°C using spray pyrolysis technique. The effect of Ts on the physical properties of Fe2O3 layers was studied. The XRD spectra reveal the formation of α-Fe2O3. The best crystallinity is obtained at Ts = 400°C. Optical analysis allows us to know that α–Fe2O3 thin films displayed a band gap from 2.07 to 2.16 eV for direct transition and from 1.67 to 2 eV for indirect transition. The maximum value of Hall mobility (µ = 62cm2.V−1. s−1) is obtained at Ts = 400°C. Hence, the obtained result of gas sensing proves that α-Fe2O3 has good sensitivity and stability at operating temperature equal to 300°C. Besides, CuO/α-Fe2O3/ZnO has a photovoltaic effect. That the open circuit voltage (Voc) and short circuit current density (Jsc) are equal to 0.5 V and 0.43 mA/cm2 respectively.

Growth of AlN Crystal Using Reactive Sputtering Method With Variation of Nitrogen Gas Pressure and Substrate Temperature

Today’s semi-conductor technology continues to develop, both in terms of material discovery, manufacturing technique, as well as implementation and the development. In this research, the researcher will utilize the AlN synthesis with a reactive sputtering method on the substrate SiO2 that has done with variation substrate temperature of (200, 250, 300 o C), and the nitrogen gas pressure of 10, 15 and 20 mBar. This study successfully synthesize nanomaterial AlN with a hexagonal crystal system and shows the wurtzite phase is formed. While morphology AlN formed composed of particles - spherical shaped particles. From this research it is known that raising the temperature of the substrate produces more uniform morphology and homogeneous, the surface roughness is formed from 15,4 to 84 nm and obtained the crystal size is 64-87 nm. While the addition of nitrogen gas pressure causes the better crystallinity. The research obtained AlN with Optical Transversal wave type at a wavenumber of 600-670 cm-1. While the growth of AlN crystal growth of AlN is best obtained on the parameters of the substrate temperature 290 °C and nitrogen gas pressure of 20 mbar.

Crystallographic texture study of pulsed laser deposited Cr2O3 thin films

Chromium oxide thin films of thickness ~140 nm were grown on c-plane (0001) and a-plane (112¯0) sapphire substrates by Pulsed Laser Deposition (PLD) technique. The films of Cr2O3 on Si (100) substrates have been synthesized at an optimized oxygen partial pressure of 2 Pa with varying substrate temperature in the range of 473-973 K. It was observed that the films deposited at temperatures ≥673 K are crystalline as confirmed by X-Ray Diffraction (XRD) studies. The X-Ray Photoelectron Spectroscopy (XPS) profile showed that the films were grown with Cr3+ oxidation state. Atomic Force Microscopy (AFM) revealed smooth, uniform surface morphology with small amount of porosity. The epitaxial nature of the film on sapphire substrate and crystallographic orientation of the Cr2O3 over Si substrate were studied using rocking curve, ϕ (Phi) scan and pole figure measurement. Pole figure analysis suggested that the films deposited on Si substrate were fiber textured. Rocking curve Full Width at Half Maximum (FWHM) for Cr2O3 (0006) and Cr2O3 (112¯0) was about 0.1° and 0.06° respectively, which indicate the good quality of crystalline film. High Resolution X-ray Diffraction (HRXRD) with reciprocal space mappings (RSM) measurements indicate that the films grown on sapphire substrates are in relaxed state.

Enhanced process stability for the low temperature sputter deposition of aluminium nitride thin films

MEMS (micro electro-mechanical systems) operated in resonance and excited piezoelectrically are nowadays used for a broad range of different application scenarios. To enhance the process stability and hence, the reproducibility of key film parameters of sputter-deposited aluminium nitride such as the film stress, the piezoelectric coefficient d33 and low leakage current levels, a novel aluminium clamped substrate holder is reported. Compared to the standard molybdenum based solution, where the thermal contact between the wafer and substrate holder varies during deposition, as the wafer can move freely, the substrate temperature variations are substantially reduced due to clamped configuration. Independent of AlN film thickness ranging between 0.5 μm and 2.0 μm the scatter in piezoelectric constant d33 and leakage current characteristics represented by the barrier height and the activation energy is reduced up to a factor of 3. These results demonstrate the importance to control carefully the temperature conditions during low-temperature AlN deposition to ensure a high reproducibility in film properties.

Geometric and compositional factors on critical current density in YBa2Cu3O7−δ films containing nanorods

Critical current density (Jc) was investigated in YBa2Cu3O7−δ films containing nanorods prepared with various nanorod materials, with variation of nanorod content, substrate temperature, and oxidization condition. Three types of compositional situation were realized: films containing strain induced oxygen vacancies; fully oxidized films containing cation compositional deviation; and oxygen deficient films. Normalized Jc−B behavior was determined via the matching field, which is a geometric factor, regardless of the compositional details. A Jc−critical temperature (Tc) relation depending on distribution and fraction of compositional deviation (cation compositional deviation and strain induced oxygen vacancies) was found: the Jc values decreased with decreasing Tc due to the effect of Tc on nanorod pinning strength in the fully oxidized films; Jc decreased with decreasing oxygen pressure in the film cooling process after film deposition in spite of Tc remaining almost the same, due to reduction of the effective area for current flow in the oxygen deficient films. Thus, a Jc landscape based on geometric and compositional factors was obtained. The study highlights the importance of the Jc−Tc analysis in the understanding of Jc in YBa2Cu3O7−δ films containing nanorods.

Effect of substrate temperature and oxygen partial pressure on RF sputtered NiO thin films

Nickel oxide (NiO) thin films were deposited by RF sputtering process and the physical properties were investigated for varying substrate temperatures and oxygen partial pressure. The variation of the crystallographic orientation and microstructure of the NiO thin films with an increase in substrate temperature were studied. It was observed that NiO thin films deposited at 350 °C shows relatively good crystalline characteristics with a preferential orientation along (111) plane. With the optimum substrate temperature of 350 °C, the NiO thin films were deposited under various oxygen partial pressures at the same experimental conditions. The structural, optical and electrical properties of NiO thin films under varying oxygen partial pressure of 10%–50% were investigated. From XRD it is clear that the films prepared in the pure argon atmosphere were amorphous while the films in oxygen partial pressure exhibited polycrystalline NiO phase. SEM and AFM investigations unveil that the higher substrate temperature improves the microstructure of the thin films. It is revealed that the NiO thin films deposited at oxygen partial pressure of 40% and a substrate temperature of 350 °C, showed higher electrical conductivity with p-type characteristics.

Temperature correction of substrate moisture measurements made in coir in polytunnel-grown strawberries

The aim of this work is to assess the use of temperature corrected soil moisture data to improve the relationship between environmental drivers and the measurement of substrate moisture content in high porosity soil-free growing environments such as coir. Substrate moisture sensor data collected from strawberry plants grown in coir bags installed in a table-top system under a polytunnel illustrates the impact of temperature on capacitancebased moisture measurements. Substrate moisture measurements made in our coir arrangement possess the negative temperature coefficient of the permittivity of water where diurnal changes in moisture content oppose those of substrate temperature. The diurnal substrate temperature variation was seen to range from 7C to 25C resulting in a clearly observable temperature effect in substrate moisture content measurements during the 23 day test period. A temperature correction algorithm is presented in this work that has been derived from the Complex Refractive Index Model (CRIM) equation which was easily calibrated for coir and applied to the substrate moisture and temperature data. The diurnal variations seen with the temperature compensated substrate moisture data now align very well with the expected diurnal water demands of the strawberry plants. To further evaluate the relationship between environmental drivers of solar radiation and vapour pressure deficit with substrate moisture the temperature correction algorithm was programmed within a GP2 data logger. The GP2 was also collecting solar radiation, air temperature and relative humidity data. The resulting comparison of substrate moisture responses to environmental drivers illustrates a significantly improved correlation with temperature corrected substrate moisture measurements. We conclude that this new temperature correction algorithm addresses the effect of temperature on the relative permittivity of water which will affect all capacitance based sensor measurements in high porosity soil-free growing substrates such as coir.

Synthesis of active absorber layer by dip-coating method for perovskite solar cell

In this paper, we develop the hybrid perovskite-based n-i-p solar cell using a simple, fast and low-cost dip-coating method. Hot solution and the pre-annealed substrate are used for coating the perovskite thin film by this method this is further used for studying its structural and electrical properties. UV–vis spectroscopy is carried out for calculating the band gap of the hybrid perovskite layer which is ∼1.6 eV. X-ray spectroscopy confirms that the formation of hybrid perovskite layer. The profilometer is used to study the surface roughness and also for measuring the thickness of the perovskite layer with varying substrate temperature. The optimized sample was further used for cross-sectional SEM image to verify the thickness measured from the profiler. The electrical parameter of JV characteristic with varying temperature is tabulated in the table. Whereas, the perovskite sensitized solar cell exhibits highest short circuit current density, Jsc of 11 mA cm−2, open circuit voltage, Voc of 0.87 V, fill factor of 0.55 and efficiency, η of >5%.

Growth of Europium-Doped Magnesium Selenide Films by Electric Field-Assisted Spray Pyrolysis: Optical and Structural Analysis

Europium-doped MgSe films were deposited via electric field-assisted spray pyrolysis. The dopant concentration of the bulk solution of europium trioxide was 5wt. %. However, for doping the films at different substrate temperatures, volume percentage (vol. %) was employed at each instance of variation. Variation of spray temperature was around 573K and 673K (±0.3). Deposition occurred at optimized conditions. Spectra of absorption indicate poor absorption characteristics demonstrated by Europium-doped MgSe films in the ultra-violet region and very low absorption characteristics in the visible section. Absorption peaks were evident around 230nm, 240nm, 350nm and 365nm which confirmed defect states are inherent inside the crystal structure of the films. The films displayed high transparency and low reflection in the visible section at varying substrate temperatures. The high transparency revealed by the MgSe:Eu films in the visible section of the electromagnetic spectrum makes the material applicable as a coating layer in the manufacturing of transparent products. Band gap energies within the range of 2.49eV to 2.95eV corresponding to varying substrate temperatures (573K, 598K, 623K, 648K and 673K) and film thicknesses (2900nm, 2750nm, 2500nm, 2100nm and 200nm) were determined for the MgSe:Eu films. However, a clear observation shows that the band gaps of MgSe:Eu films are mainly dependent on thickness such that the obtained band gaps decreased with increasing thickness (band gap increases with thickness reduction). Structural analysis (XRD) studied at 10% and 40% Eu concentrations reveals a hexagonal (or wurzite) structure for the films with a distortion in crystallinity at higher dopant concentration (40 vol. %) and a resultant blue shift in the lattice constant from the bulk value. Multiple planes of reflection from XRD pattern of the deposited MgSe:Eu films indicate clearly that the films are polycrystalline. Surface morphology (SEM) confirms the highly strained nature and the presence of defect states within the crystal lattice of the Europium-doped MgSe films. Composition of MgSe:Eu films obtained by energy dispersive analysis x-ray (EDAX) confirms the growth of MgSe:Eu films.

Effects of substrate temperature and deposition rate on the phase separated morphology of co-sputtered, Cu-Mo thin films

We report on the evolution of phase-separated morphologies in co-sputtered Cu-Mo films as a result of varying substrate temperature and deposition rate during deposition. A transition from vertically-oriented concentration modulations to laterally-oriented modulations followed by randomly-oriented modulations was observed in the Cu-Mo films because of changing substrate temperature at constant deposition rate. A refinement of the Cu-Mo domains was observed at increasing deposition rate at a constant substrate temperature. A coarsening of phase-separated domains was also observed with increasing substrate temperature. The phase separation kinetics that controlled film morphology were limited by the surface interdiffusion of each species as the film grew in thickness. Control over the surface interdiffusion length was achieved by altering the deposition temperature and material flux.

Substrate temperature effects on structural and photoelectric properties of CdS thin films

Cadmium sulfide thin films were deposited on quartz substrates by magnetron sputtering method with varying substrate temperatures. X-ray diffraction patterns of prepared samples showed preferred orientation of (002) with pure hexagonal phase. Atomic force microscopy and scanning electron microscopy images exhibited a surface morphology with uniform and homogeneous grains. X-ray photoelectron spectroscopy (XPS) revealed peaks corresponding to cadmium, sulfur, carbon and oxygen atoms, and the high-resolution XPS surveys for cadmium 3d and sulfur 2p showed an obvious shift to lower binding energy as the substrate temperature raised. Meanwhile, the optical absorption coefficient gradually increased, and the transmittance was approximately 75%. The optical energy gap was as high as 2·40 eV at the substrate temperature of 200°C. Photoconductivity curves presented a rapid response, the lowest conductivity at steady state (only 1·6257 × 10−4 Ω−1 cm−1) and a high solar photoconductivity gain (G p = 296·36) at substrate temperatures of up to 200°C.

Noncontact measurement of substrate temperature by optical low-coherence interferometry in high-power pulsed magnetron sputtering

Substrate temperature is one of the important parameters that affect the quality of deposited films. The monitoring of the substrate temperature is an important technique of controlling the deposition process precisely. In this study, the Si substrate temperature in high-power pulse magnetron sputtering (HPPMS) was measured by a noncontact method based on optical low-coherence interferometry (LCI). The measurement was simultaneously performed using an LCI system and a thermocouple (TC) as a contact measurement method. The difference in measured value between the LCI system and the TC was about 7.4 °C. The reproducibilities of measurement for the LCI system and TC were ±0.7 and ±2.0 °C, respectively. The heat influx from the plasma to the substrate was estimated using the temporal variation of substrate temperature and increased from 19.7 to 160.0 mW/cm2 with increasing target applied voltage. The major factor for the enhancement of the heat influx would be charged species such as ions and electrons owing to the high ionization degree of sputtered metal particles in HPPMS.