Increasing Deposition Temperature Research Articles

Effects of deposition temperature on microstructure, cation distribution and electrical properties of Mn1.56Co0.96Ni0.48O4 thin films grown by RF magnetron sputtering

In this work, Mn1.56Co0.96Ni0.48O4 (MCN) thin films have been deposited at 200 °C, 400 °C and 750 °C by radio frequency magnetron sputtering. The crystallinity properties and surface morphologies of the films are greatly influenced by the deposition temperature according to the XRD and FESEM results. The ionic valence states of Mn, Co and Ni were observed by X-ray photoelectron spectroscopy (XPS), the cations distribution and formulas of the MCN films are determined. The Mn3+/Mn4+ ratio increases with the higher deposition temperature, and the films deposited at 400 °C shows maximum concentration of Mn3+-Mn4+ pairs. The results of electrical properties reveal that the resistivity of the MCN films falls down with increasing deposition temperature, while all films possess similar characteristic temperature and activation energy. The deposition temperature dependent resistivity mechanism of the MCN films was further analyzed and discussed based on the crystallinity and XPS results. This study will improve the understanding of the deposition temperature effects on MCN films, which is valuable to its better application in uncooled IR detection.

Temperature effect on the mechanical behaviour of niobium nitride thin films

Niobium nitride is used in a wide range of application due to its mechanical, physical, chemical, electrical and optical properties. The main aim of this paper is to deposit niobium nitride thin films by direct current magnetron sputtering and to characterize them at nanoscale. The films were deposited on silicon Si (100) substrates. Three types of films were deposited by modifying the deposition temperature. In this regard, some of the samples were deposited at room temperature (25 °C), some were deposited when the substrate was preheated at 200 °C, and the rest at substrate temperature of 400 °C. Regarding the topography of the samples, an increase in the average roughness was determined with the increase in deposition temperature. The nanoindentation tests were carried out at temperatures between 20 and 100 °C so that to emphasize the change in hardness and modulus of elasticity in terms of testing temperature. The results pointed out an important influence of both the deposition temperature and testing temperature on the topography, adhesion and mechanical properties of the niobium nitride thin films.

Influence of PECVD deposition temperature on phosphorus doped poly-silicon passivating contacts

This paper describes the influence of plasma enhanced chemical vapor deposition (PECVD) deposition temperature on heavily doped silicon based (doped-Si/SiOx) passivating contacts for silicon solar cells. The doped-Si films are obtained by PECVD intrinsic amorphous silicon (a-Si) and a subsequent thermal POCl3 diffusion process. By changing the deposition temperature of PECVD, a-Si films with different degrees of crystallinity and density can be obtained. These differences between the a-Si films result in different properties of the passivating contacts in terms of passivation quality and carrier selectivity. By exploring a range of PECVD deposition temperatures from 250 °C to 470 °C, the best passivation quality is obtained at a temperature of 420 °C. On the other hand, the contact resistivity decreases with increasing deposition temperature. After studying the a-Si properties and the resulting passivating contact properties, we obtain optimal passivating contacts with a high implied open-circuit voltage (iVoc) of 742 mV and a low contact resistivity ρc of 6.4 mΩ∙cm2.

Structural and luminescence studies on TiO2-MoO3 thin films

Thin films of MoO3 and TiO2-MoO3 were deposited on quartz glass and Silicon (100) substrates by dc magnetron sputtering at two substrate temperatures of 300 K and 600 K and at two sputtering pressure of 5 Pa and 10 Pa and sputtering power of 50 W respectively. The deposited films were characterized by X-ray Photo Electron Spectroscopy (XPS), Raman and photoluminescence spectra. The pure MoO3 films deposited at 300 K exhibited the Raman bands at 242 cm−1 and 974 cm−1 indicating the absorption of water molecules and formation of alpha MoO3-H2O. With increasing Ti content the bands are shifted to 224 cm−1 and 960 cm−1 that correspond to h-MoO3 and absorption of water molecules. For Ti at. % of 2.4 the bands were observed only at low frequencies but at high temperatures, a single peak noticed at 954 cm−1 corresponds to α – MoO3 H2O. The Photo-luminescence spectrum reveals that the MoO3 films deposited at 5 Pa and 300 K exhibits Near Band Edge (NBE) transition at 324 nm. The intensity of NBE increases further and with corresponding shift towards higher wavelength with TiO2 doping. The TiO2 doping also introduces Deep Level (DL) emission in TiO2-MoO3 composite film. With increase of deposition temperature the intensity of emission due to NBE in MoO3 films decrease introducing DL emission. The TiO2 doping enhances the intensity of both NBE and DL emission with a shift in emission wavelength towards higher value. The intensity of these NBE and DL emissions are further increasing with increasing sputtering pressure (10 Pa) and deposition temperature (600 K) of MoO3 and TiO2-MoO3.

Analysis and Study of Characteristic FTIR Absorption Peaks in Hafnium Oxide Thin Films Deposited at Low-Temperature

In this study, hafnium oxide (HfO2) thin films were deposited by spin coating technique at different low deposition temperatures (150 °C, 200 °C and 250 °C). The properties of the films were measured by UV–visible spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflectance mode. The films exhibit the typical absorption peaks related to Hf–O bonds. Interestingly, a trend is clearly observed between the transmittance, crystallographic planes and FTIR characteristic peaks as deposition temperature increases. Moreover, the fabrication and characterization of MOS capacitors is presented. The current–voltage and capacitance–voltage curves corroborated the trend observed in the characterization of the HfO2 films.

Influence of Cd on structure, surface morphology, optical and electrical properties of nano crystalline ZnS films

Transparent nano crystalline Zn1-xCdxS films were grown on glass substrates at 0.0125 M precursor concentration using chemical spray pyrolysis technique. The suitable optimized temperatures were adjusted from 673 K to 573 K for different compositions. The films with x< 0.40 have exhibited cubic phase with the crystalline plane of (1 1 1) orientation and for x> 0.30 have shown a hexagonal phase with (0 0 2) prominent plane. The lattice constants, crystallite size and dislocation density in the samples were estimated using X-ray diffraction data. The morphology of the films with higher Zn content exhibits fibrous structure and it changes to grain like structure on decreasing Cd concentration. XPS and EDAX analysis confirms the presence of elements in the deposits. The optical transmittance and energy band gap increased with increasing deposition temperature, whereas, decreased with increasing Cd dopant. The NLO behavior of the deposits indicates free carrier absorption induced two photon absorption processes. All deposits have shown n-type electrical conductivity. The film resistivity decreases with increase in deposition temperature and Cd content. The obtained Zn1-xCdxS films are suitable for device application of gas sensor and optical limiter.

Influence of deposition temperature on the structure, optical and electrical properties of a-C films by DCMS

Amorphous carbon films have been considered as strongly promising semiconductor materials, due to their superior mechanical properties, specific bond structures, as well as facile deposition over large area with device integrated processes. To figure out the effect of sp2/sp3 ratio and size of sp2 clusters on opto-electrical behavior, we fabricated a series of H-free amorphous carbon (a-C) films by magnetron sputtering with a controllable deposition temperature from 30 to 400 °C. Result showed that all the films displayed a strong light absorption in the ultraviolet and visible regions, where the transmittance was less than 5% in the wavelength range of 200–750 nm, demonstrating the typical semiconductor behavior in temperature from 5 to 350 K, exhibiting a lower resistivity at higher temperature. In addition, their transmittance, optical bandgap, resistivity and activation energy showed similar tendency with increasing deposition temperature, which was discussed in terms of the evolution of sp2/sp3 ratio and sp2 cluster in the a-C films. These studies provide a new route to tune optical and electrical properties of a-C films for their opto-electrical applications.

Effect of microstructure on impact resistance of chemical vapor deposited SiC coating on graphite substrate

SiC coatings were prepared by chemical vapor deposition at 1050 °C, 1100 °C, 1150 °C, and 1200 °C by using methyltrichlorosilane (MTS, CH3SiCl3) as the precursor. The compositions, microstructures, and deposition kinetics of the coatings were studied. The results show that the main constituent of the as-prepared coatings is 3C–SiC with a small amount of free C at deposition temperatures above 1100 °C. The coating has a regular fine-grain structure at 1050 °C, umbrella-shaped structure at 1100 °C, and columnar structure at 1150 °C and 1200 °C with the deposition process being controlled by surface kinetics and diffusion kinetics, respectively. The impact resistance was tested using a Split Hopkinson Pressure Bar system. The impact resistance of the graphite substrate is improved by the as-prepared SiC coating evidently. The impact strength of the coating sample increases with increasing deposition temperature, reaching the maximum at 1150 °C, and declines slightly at 1200 °C. The stress-strain curves under dynamic impact resistance loading, and the surface morphologies and microstructures resulting from the impact tests of the different SiC coatings are discussed in detail. The factors affecting impact resistance are mainly the thickness and hardness values of the as-prepared coatings.

Low-Temperature Atomic Layer Deposition of Highly Conformal Tin Nitride Thin Films for Energy Storage Devices.

We present an atomic layer deposition (ALD) process for the synthesis of tin nitride (SnNx) thin films using tetrakis(dimethylamino) tin (TDMASn, Sn(NMe2)4) and ammonia (NH3) as the precursors at low deposition temperatures (70-200 °C). This newly developed ALD scheme exhibits ideal ALD features such as self-limited film growth at 150 °C. The growth per cycle (GPC) was found to be ∼0.21 nm/cycle at 70 °C, which decreased with increasing deposition temperature. Interestingly, when the deposition temperature was between 125 and 180 °C, the GPC remained almost constant at ∼0.10 nm/cycle, which suggests an ALD temperature window, whereas upon further increasing the temperature to 200 °C, the GPC considerably decreased to ∼0.04 nm/cycle. Thermodynamic analysis via density functional theory calculations showed that the self-saturation of TDMASn would occur on an NH2-terminated surface. Moreover, it also suggests that the condensation of a molecular precursor and the desorption of surface *NH2 moieties would occur at lower and higher temperatures outside the ALD window, respectively. Thanks to the characteristics of ALD, this process could be used to conformally and uniformly deposit SnNx onto an ultranarrow dual-trench Si structure (minimum width: 15 nm; aspect ratio: ∼6.3) with ∼100% step coverage. Several analysis tools such as transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and secondary-ion mass spectrometry were used to characterize the film properties under different deposition conditions. XRD showed that a hexagonal SnN phase was obtained at a relatively low deposition temperature (100-150 °C), whereas cubic Sn3N4 was formed at a higher deposition temperature (175-200 °C). The stoichiometry of these thermally grown ALD-SnNx films (Sn-to-N ratio) deposited at 150 °C was determined to be ∼1:0.93 with negligible impurities. The optoelectronic properties of the SnNx films, such as the band gap, wavelength-dependent refractive index, extinction coefficient, carrier concentration, and mobility, were further evaluated via spectroscopic ellipsometry analysis. Finally, ALD-SnNx-coated Ni-foam (NF) and hollow carbon nanofibers were successfully used as free-standing electrodes in electrochemical supercapacitors and in Li-ion batteries, which showed a higher charge-storage time (about eight times greater than that of the uncoated NF) and a specific capacity of ∼520 mAh/g after 100 cycles at 0.1 A/g, respectively. This enhanced performance might be due to the uniform coverage of these substrates by ALD-SnNx, which ensures good electric contact and mechanical stability during electrochemical reactions.

Temperature-dependent structural, morphological and optical properties of chemical bath-deposited CdS films

Cadmium sulfide (CdS) films were grown on top of the fluorine-doped tin oxide (FTO) coated glass substrates at four different bath temperatures by chemical bath deposition (CBD) technique. X-ray diffraction (XRD), ultraviolet–visible (UV–Vis) spectrometry, energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscope (FESEM), photoluminescence (PL) and Fourier-transform infrared (FTIR) analyses were employed to examine the morphological and optical properties of deposited films. XRD studies confirmed the cubic crystalline nature of the deposited films which improved with increase in deposition temperature, and EDX along with FESEM study showed that the films were smooth and uniform with appropriate chemical composition. Band-gap values of the CBD CdS films calculated by UV–Vis spectrometry were found to be in the range of 2.32–2.39 eV. A strong blue band and a weak green band were observed in PL emission spectra. C–S, Cd-S and S–C–N vibrations were found by FTIR spectral analysis.

Plasma-enhanced atomic layer deposition of vanadium nitride

This work describes process development and associated characterization of a plasma-enhanced atomic layer deposition process for vanadium nitride (VN) using tetrakis(dimethylamido)vanadium and nitrogen plasma over a deposition temperature range from 150 to 300 °C. The authors characterize these films using x-ray photoelectron spectroscopy, x-ray diffraction, spectroscopic ellipsometery, and tribological measurements to determine the films' chemistry, structure, and wear resistance. Overall, they demonstrate a stable VN growth window between 250 and 350 °C, with deposition temperatures below this leading to incomplete reaction between the precursors. Film crystallinity increases with increasing deposition temperature based on the VN cubic (020) peak area increase. Atomic layer deposition VN films show excellent tribological properties with an average wear rate of 7.7 × 10−8 mm3/N m and a friction coefficient of 0.38.

Temperature-controlled conversion from Fe–Si particles to integrated Fe–Si/SiO2 core–shell structure particles during fluidised bed chemical vapour deposition

In the synthesis of ferromagnetic/SiO2 core–shell structures, the minimum formation conditions and evolution mechanism are worth investigating. In the present study, to determine the minimum formation temperature of an integrated Fe–Si/SiO2 core–shell structure during chemical vapour deposition in a fluidised bed, the effects of deposition temperature on the structural and magnetic performances of SiO2 insulation coatings on Fe–Si particles were investigated. Thermodynamic calculations and differential scanning calorimetry were used to understand the thermal decomposition of C8H20O4Si. The results of the theoretical and structural studies showed that the minimum deposition temperature of the amorphous SiO2 insulation coating on the Fe–Si particle surface was ~880 K and that the Fe–Si/SiO2 composite structure started to convert into an integrated Fe–Si/SiO2 core–shell structure after the deposition temperature was raised above 920 K. The increase in the thickness of the SiO2 insulation layer due to the increased deposition temperature was studied using X-ray diffraction and scanning electron microscope analyses. The results of X-ray photoelectron spectroscopy showed that four and five types of electronic structures existed in the SiO2 insulation shell for silicon and oxygen, respectively, and that only 32.74 at.% of the oxygen from the Si(OSi)3(OH) group interacted with the Fe–Si alloy surface. The results of the performance test indicated that the integrated Fe–Si/SiO2 core–shell structure led to a substantial enhancement in the electrical resistivity of the particles and reduction in their saturation magnetisation, but hardly affected the coercive force.

Synthesis of Intermetallic (Mg1−x,Alx)2Ca by Combinatorial Sputtering

The synthesis–composition–structure relationship in the Mg–Ca–Al system is studied using combinatorial magnetron sputtering. With increasing deposition temperature, a drastic decrease in Mg concentration is obtained. This behavior can be understood based on density functional theory calculations yielding a desorption energy of 1.9 eV/atom for Mg from a hexagonal Mg nanocluster which is far below the desorption energy of Mg from a Mg2Ca nanocluster (3.4 eV/atom) implying desorption of excess Mg during thin film growth at elevated temperatures. Correlative structural and chemical analysis of binary Mg–Ca thin films suggests the formation of hexagonal Mg2Ca (C14 Laves phase) in a wide Mg/Ca range from 1.7 to 2.2, expanding the to date reported stoichiometry range. Pronounced thermally-induced desorption of Mg is utilized to synthesize stoichiometric (Mg1−x,Alx)2Ca thin films by additional co-sputtering of elemental Al, exhibiting a higher desorption energy (6.7 eV/atom) compared to Mg (3.4 eV/atom) from Mg2Ca, which governs its preferred incorporation during synthesis. X-ray diffraction investigations along the chemical gradient suggest the formation of intermetallic C14 (Mg1–x,Alx)2Ca with a critical aluminum concentration of up to 23 at.%. The introduced synthesis strategy, based on the thermally-induced desorption of weakly bonded species, and the preferential incorporation of strongly bonded species, may also be useful for solubility studies of other phases within this ternary system as well as for other intermetallics with weakly bonded alloying constituents.

Electrical properties of the HfO2/Al2O3 dielectrics stacked using single- and dual-temperature atomic-layer deposition processes on In0.53Ga0.47As

For sequential stacking of an Al2O3 passivation layer and a main HfO2 gate dielectric layer on In0.53Ga0.47As, we used single- and dual-temperature atomic-layer deposition processes, and systematically compared their effects on the dielectric-related electrical properties. When the deposition of Al2O3 passivation layer (approximately 0.7−0.8 nm) took place at relatively low temperatures of 100 °C, an increase in the subsequent deposition temperature for HfO2 (from 100 to 300 °C) assisted in decreasing both capacitance-equivalent oxide thickness and the number of bulk-related traps. However, the valuable reduction in both near-interface defect density and leakage current through the low-temperature Al2O3 passivation approach was monotonically lessened with an increase in the process temperature for the subsequent HfO2 deposition, which suggests the need for a careful optimization of a thermal budget for the dual-temperature process.

Influence of deposition conditions on nanostructured InSe thin films

In this study, nanostructured indium selenide (InSe) thin films were deposited on Indium tin oxide (ITO)-coated glass substrate using electrochemical deposition (ECD) from aqueous solution containing In(SO4)3.H2O and SeO2. The effects of deposition potential (−0.70 to −1.35 V), time (30-3600 s), temperature (25-80 °C) and pH (2.58 for A samples; 2 for B samples and 1.45 for C samples) on growth of the InSe thin films were examined in terms of their structural, morphological and optical properties. X-ray diffraction (XRD) analysis confirmed that the InSe thin films are in polycrystalline structure. It was found that the values of grain size decreased and the full width half maximum (FWHM) values increased with the increasing deposition potential. According to the absorption measurements, optical properties of the thin films varied with changes in deposition conditions. Based on the atomic force microscopy (AFM) and the scanning electron microscopy (SEM) images, surface morphology of the thin films was influenced by deposition potential and pH of the electrolyte, and non-homogeneous depositions distributed across the entire surface were observed. In addition, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR) analyses were used to further examine crystal quality, vibration, chemical binding conditions, In/Se orientation and structure of the prepared InSe thin films. When Raman results are examined, the B12 sample shows a more intensity and narrow peak at 248 cm−1. XPS measurements sowed that A6 sample exhibited more growth in low potential for a long time and better film stoichiometry compared to the other three samples. Also, FT-IR studies prove the presence of InSe. According to the results, the film did not form at low temperatures and short times. However, the film formation began with the increasing deposition temperature and time at the low potential value of −0.730 V. But, it is clear that a high quality film can be obtained in cathodic potential with −1.3 V and shorter deposition time with 300 s at room temperature respectively. Overall results showed that the high quality thin films can be obtained by the ECD technique. However, deposition conditions must be sensitively adjusted to control morphology of the electrodeposited nanoparticles.

Stress relaxation through thermal gradient structure of tetrahedral amorphous carbon thin film deposited on Ge–Se–Sb-based chalcogenide glass

Surface thermal gradient effects, which can improve interfacial adhesion between chalcogenide glasses and tetrahedral amorphous carbon (ta-C) films, are used to relax intrinsic stress at the ta-C deposition temperature. The intrinsic stress of ta-C is difficult to control through substrate bias voltage applied to the insulating substrate; however, under increased deposition temperatures, thermal stress is generated by the different thermal expansion coefficients of the ta-C film and the chalcogenide glass. Here, an ion source was used to increase the substrate temperature at the initial stage of deposition to simultaneously relax the thermal and intrinsic stresses. The 100-nm-thick ta-C coating film was applied by filtered cathodic vacuum arc deposition. The ta-C coating was deposited at varying surface temperatures. At the effective surface temperature of 80 °C, the adhesive strength exceeded 12.5 N/mm. In Raman and infrared (IR) transmittance spectral results, the I(D)/I(G) ratio was increased and the IR transmittance was decreased by 2%.

Interaction of Methane Concentration and Deposition Temperature in Atmospheric Laser Based CVD Diamond Deposition on Hard Metal

For laser-based plasma chemical vapour deposition (CVD) of diamond on hard metal at atmospheric pressure, without a vacuum chamber, the interaction between the deposition temperature and the methane concentration has to be understood to adjust the coating thickness, deposition duration, and medium diamond crystal size. The hypothesis of this study is that a wider range of methane concentrations could be used to deposit microcrystalline diamond coatings due to the increasing etching and deposition rates with rising deposition temperatures. The deposition of the CVD diamond coatings was carried out on K10 hard metal substrates. The process temperature and the methane concentration were varied from 650 to 1100 °C and from 0.15% to 5.0%, respectively. The coatings were analysed by scanning electron and 3D laser-scanning confocal microscopy, energy dispersive X-ray and micro-Raman spectroscopy, as well as cryofracture-based microscopy analysis. The results showed that microcrystalline diamond coatings could be deposited in a wider range of methane concentrations when increasing the process temperature. The coating thickness saturates depending on the process temperature even though the methane concentration constantly increases. The coating thickness increases with an increasing deposition temperature until the cobalt diffusion hinders the deposition at the process temperature of 1100 °C.

Impact of Al2O3 deposition temperature on the performance and initial stability of nanocrystalline ZnO thin-film transistors

The initial performance and “time-zero” instability of ZnO TFTs are evaluated using different Al2O3 deposition temperature. Fully-patterned bottom-gate and top-contact devices were fabricated and used as the test structures. The initial TFT performance shows a decrease of saturation mobility from 9.2 to 5.6 cm2/Vˑs; increase in threshold voltage from 2.2 to 2.5 V; and subthreshold swing increase from 115 to 225 mV/DEC, with increasing deposition temperature. The time-zero instability (t = 0 s) shows an increase in threshold voltage shifting of 4.0, 12.8, and 13.6%; a decrease in the subthreshold swing of 5.3%, 17.7%, and 16.3%; and an increase in saturation mobility of 0.8%, 2.8%, and 4.3% with increasing deposition temperature. Results indicate that the primary mechanism of the threshold voltage shifting is the increase in roughness induced interface states due to possible dangling bonds increasing along with the roughness.

Growth and carrier transport performance of single-crystalline monolayer graphene over electrodeposited copper film on quartz glass

The synthesis of single crystal graphene domains on cold rolling Cu foil has recently been reported. However, the cold rolling Cu foils have many rolling lines that increase the roughness of the foil. In this work, we developed an electrodeposited method to achieve high-quality Cu film on which the nucleation density of graphene decreased greatly. The Cu film was electrodeposited over chemical plated silver film on quartz glass. The roughness and thickness of the Cu film were positively correlated with the deposition temperature and current density, respectively. High-quality single crystal graphene with low nucleation density was achieved on electrodeposited Cu film. With increasing deposition temperature of Cu film from 20 to 65 °C, the nucleation density of graphene increased from 124 to 448 mm−2. The nucleation density of graphene increased from 124 to 192 mm−2 with increasing current density from 0.03 to 0.07 A/cm−2. Finally, a back-gated graphene field effect transistor (FET) was fabricated with a carrier transport performance of μh = ~4041 cm2V−1s−1 and μe = ~2580 cm2V−1s−1 at room temperature.

Temperature Dependence of AlF3 Protection on Far-UV Al Mirrors

More efficient and stable far ultraviolet (FUV) mirrors will enable future space observatories. Traditional FUV mirrors are based on MgF2-protected Al. AlF3 has been identified as a promising substitute for MgF2 to prevent Al oxidation. Hence, the reflectivity, stability, and morphology of AlF3-protected Al mirrors have been investigated as a function of deposition temperature of the AlF3 film. In this work, it is shown how AlF3 deposition temperature is an important parameter whose optimization ultimately yields valuable throughput enhancement and improved endurance to large storage periods. Al films were deposited at room temperature (RT) and AlF3 protective layers were deposited at temperatures ranging from RT to 350 °C. It was found that the optimum AlF3 deposition temperature was between 200 and 250 °C, yielding the largest FUV reflectance and a better stability of the mirrors, which had been stored in a desiccator environment. Increasing AlF3 deposition temperature resulted in an increase in film density, approaching bulk density at 250 °C. The morphology of Al and AlF3 films as a function of AlF3 deposition temperature was also investigated. The increase in the AlF3 deposition temperature resulted in a decrease of both Al and AlF3 surface roughness and in the growth of the grain width at the AlF3 outer surface. It also resulted in a trend for the prevalent (111) planes of Al nanocrystals to orient parallel to the coating surface.