Deposition Annealing Treatment Research Articles

Structural and Optical Properties of Electrodeposited Porous SnO2 Films: Effect of Applied Potential and Post Deposition Annealing Treatment

SummaryNanocrystalline SnO2 film was prepared by cathodic electrodeposition method and its structure and optical properties were studied by X‐ray diffraction, scanning electron microscopy and UV–visible spectroscopy. The effects of applied potential and post deposition annealing on the structural and optical properties of the SnO2 were studied. It was observed from XRD that, the SnO2 film synthesized at 3 V and annealed at 250 °C showed orthorhombic phase with crystallite size of about 10 nm. The morphological study revealed that the samples having porous nature with the network of spherical shape particles. From UV–visible absorption, the band gap of sample was observed of about 3.9 eV. The water contact angle measurements were studied to see the effect of annealing temperature on the hydrophilicity/ Wettability of the film. The SnO2 surface was hydrophilic, but its hydrophilicity decreased considerably after post deposition annealing. Further the samples were used for dye sensitized solar cell applications and the results were discussed.

Effect of radio frequency power and thickness on the electrochemical properties of Li2−x MnO3−y thin films

In the present work, Li2−x MnO3−y (LMO) thin films have been deposited by radio frequency (RF) reactive magnetron sputtering using acid-treated Li2MnO3 powder target. Systematic investigations have been carried out to study the effect of RF power on the physicochemical properties of LMO thin films deposited on platinized silicon substrates. X-ray diffraction, electron microscopy, surface chemical analysis and electrochemical studies were carried out for the LMO films after post deposition annealing treatment at 500 °C for 1 h in air ambience. Galvanostatic charge discharge studies carried out using the LMO thin film electrodes, delivered a highest discharge capacity of 139 μAh μm−1 cm−2 in the potential window 2.0–3.5 V vs. Li/Li+ at 100 W RF power and lowest discharge capacity of 80 μAh μm−1 cm−2 at 75 W RF power. Thereafter, the physicochemical properties of LMO films deposited using optimized RF power 100 W on stainless steel substrates has been studied in the thickness range of 70 to 300 nm as a case study. From the galvanostatic charge discharge experiments, a stable discharge capacity of 68 μAh μm−1 cm−2 was achieved in the potential window 2.0–4.2 V vs. Li/Li+ tested up to 30 cycles. As the thickness increased, the specific discharge capacity started reducing with higher magnitude of capacity fading.

Early Effect for 28nm HK/MG PMOSFETs after Post Deposition Annealing Treatment

Exposing the Early effect (or called channel-length modulation effect) at deep subnano node high-k/metal gate (HK/MG) process is still beneficial to IC designers to reduce the obsession in design. This effect contributes the operating point in circuit concern and process adjustment. For the long channel device, the intercept under various gate voltages focuses on one point consistent with conventional device. However, the divergent phenomenon was observed at the short channel tested device due to the higher strain effect, causing the non-uniform electrical field distribution in channel.

Investigations On Sputter Deposited LiCoO2 Thin Films From Powder Target

LiCoO2 thin films used as cathode layers in thin-film solid-state batteries have been deposited from LiCoO2 powder target using radio frequency (rf) magnetron sputtering in a cost effective approach in terms of material consumption and processing time. Xray diffraction (XRD) studies of the films after post deposition annealing treatment revealed (104) orientation, which is the characteristic of rf sputtered LiCoO2 films. Raman spectroscopy was used to identify the different modes of vibration of atoms in the film. The surface morphology and cross-section of the samples were characterized using field emission scanning electron microscopy (SEM). The chemical analysis of LiCoO2 thin films was examined by X-ray photoelectron spectroscopy (XPS) showed atomic ratio of Li/Co as 0.9 which is close to the ideal value 1. Electrochemical characterization such as charge – discharge and cyclic voltammetry were conducted for LiCoO2 films deposited on platinized silicon substrates in the potential range 3.0 to 4.2 V vs Li/Li + . The maximum discharge capacity of 64 µAh.µm -1 . cm -2 and 52 µAh. µm -1 .cm -2 were achieved when discharged at a current of 5 µA and 50 µA for the first discharge cycle respectively. Moreover the electrochemical investigations of LiCoO2 thin films on flexible copper substrates also investigated and achieved an initial discharge capacity of 83 mAh/g. The possible reasons for degradation in the electrochemical properties have been discussed. The present work indicates suitability of sputtering from powder targets for thin film battery fabrication. Copyright © 2013 VBRI press.

PECVD based silicon oxynitride thin films for nano photonic on chip interconnects applications

Thin silicon oxynitride (SiOxNy) films were deposited by low temperature (∼300°C) plasma enhanced chemical vapour deposition (PECVD), using SiH4, N2O, NH3 precursor of the flow rate 25, 100, 30sccm and subjected to the post deposition annealing (PDA) treatment at 400°C and 600°C for nano optical/photonics on chip interconnects applications. AFM result reveals the variation of roughness from 60.9Å to 23.4Å after PDA treatment with respect to the as-deposited films, favourable surface topography for integrated waveguide applications. A model of decrease in island height with the effect of PDA treatment is proposed in support of AFM results. Raman spectroscopy and FTIR measurements are performed in order to define the change in crystallite and chemical bonding of as-deposited as well as PDA treated samples. These outcomes endorsed to the densification of SiOxNy thin films, due to decrease in SiN and SiO bonds strain, as well the OH, NH bonds with in oxynitride network. The increase in refractive index and PL intensity of as deposited SiOxNy thin films to the PDA treated films at 400°C and 600°C are observed. The significant shift of PL spectra peak positions indicate the change in cluster size as the result of PDA treatment, which influence the optical properties of thin films. It might be due to out diffusion of hydrogen containing species from silicon oxynitride films after PDA treatment. In this way, the structural and optical, feasibility of SiOxNy films are demonstrated in order to obtain high quality thin films for nano optical/photonics on chip interconnects applications.

Corrosion Behavior of CrN/AlSiN Multilayer Coatings on AISI 304 Stainless Steel in Aluminum Alloy Melt

In recent years, advances in coating deposition technologies have led to the development of nano-structured coating materials with unique properties. Among the many systems, Cr-Al-Si-N coatings have a variety of interesting properties such as the superhardness (~40 GPa), thermal stability with high-temperature oxidation resistance. These coatings were characterized as nanocomposites consisting of nanocrystalline CrN or CrAlN embedded in amorphous Si3N4 matrix. Nevertheless extensive discussion has been focused on the mechanical and thermal properties of Cr-Al-Si-N coating, the corrosion resistance at higher temperature is not reported yet. Therefore, the main target of this study is to evaluate the corrosion resistance of the CrN/AlSiN multilayer coating which was synthesized by cathodic arc deposition with Cr and Al88Si12 dual cathodes. The as-deposited coating was following conducted with heat treatment in nitrogen atmosphere at the temperature of 400 oC, 600 oC and 800 oC for 1 hour, respectively. Microstructure of the heated films is analyzed by X-ray photoelectron spectroscope, X-ray diffractometer and scanning electron microscopy. The corrosion resistance of the heated CrN/AlSiN coatings was studied by dipping in the aluminum alloy melt for 3 hours. The results turned out that the better corrosion resistance of CrN/AlSiN multilayer coated stainless steel was obtained by post deposition annealing treatment in nitrogen at 400 oC and 600 oC if compared to that of the other samples.

Impact of post deposition annealing in the electrically active traps at the interface between Ge(001) substrates and LaGeOx films grown by molecular beam deposition

Changes in the electron trapping at the interface between Ge substrates and LaGeOx films grown by atomic O assisted molecular beam deposition are inferred upon post deposition annealing treatment on the as-deposited films from electrically detected magnetic resonance (EDMR) spectroscopy and from the electrical response of Pt/LaGeOx/Ge metal oxide semiconductor (MOS) capacitors. The improved electrical performance of the MOS capacitors upon annealing is consistent with the EDMR detected reduction of oxide defects which are associated with GeO species in the LaGeOx layer as evidenced by x-ray photoelectron spectroscopy.

Surface vs bulk phase transitions in semiconducting polymer films for OPV and OLED applications

Post deposition annealing treatments are considered one of the most important and effective ways to increase the performance of polymer-based thin films for organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs).Hence, thermally induced morphological changes such as phase transitions are key phenomena which can have a determinant influence on the final properties and stability of the materials and devices based upon them. In this work, we have successfully proven that in-situ atomic force microscopy (AFM) and Raman spectroscopy can be used to measure the cold crystallization transition temperature of the widely studied blue-emitting polymer poly(9,9-dioctylfluorene) (PFO) and the workhorse system for photovoltaics based on mixtures of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Raman, as a bulk probe, evidences lower crystallization temperatures for PFO and P3HT films compared to those obtained at the surface with AFM which suggest the existence of morphological and/or molecular mobility differences between the bulk and the surface.

Silicon Nanoclusters Embedded into Oxide Host for Non-Volatile Memory Applications

Non-volatile memory structures with embedded silicon nanoclusters were fabricated by RF magnetron sputtering approach. The capacitance-voltage characteristics of classical SiO2/Si-ncs-SiO2/SiO2 and HfO2/Si-ncs-SiO2/SiO2 structures have been compared. The specific deposition conditions and annealing treatment allowed a large memory window of about 6.8 V at a sweeping voltage of ± 6 V to be achieved. It was observed that the similar memory capacitance can be obtained for classical SiO2/Si-ncs-SiO2/SiO2 structures using multilayer charge storage node. The analysis of microstructural properties of the samples revealed that an annealing at 1000-1100°C results in the formation of crystallized silicon clusters, while the crystallization of HfO2 occurred with a tetragonal phase. It was also revealed that an annealing treatment at 950°C, at which amorphous Si clusters are formed, allowed a highest memory window to be obtained. This result indicates the benefit of low thermal budget treatment for low operating voltage non-volatile memory devices.

Hf-based high-k materials for Si nanocrystal floating gate memories

Pure and Si-rich HfO2 layers fabricated by radio frequency sputtering were utilized as alternative tunnel oxide layers for high-k/Si-nanocrystals-SiO2/SiO2 memory structures. The effect of Si incorporation on the properties of Hf-based tunnel layer was investigated. The Si-rich SiO2 active layers were used as charge storage layers, and their properties were studied versus deposition conditions and annealing treatment. The capacitance-voltage measurements were performed to study the charge trapping characteristics of these structures. It was shown that with specific deposition conditions and annealing treatment, a large memory window of about 6.8 V is achievable at a sweeping voltage of ± 6 V, indicating the utility of these stack structures for low-operating-voltage nonvolatile memory devices.

Electrical Characteristics of Crystalline Gd2O3 Film on Si (111): Impacts of Growth Temperature and Post Deposition Annealing

AbstractThis work reports on the epitaxial growth of crystalline high-k Gd2O3 on Si (111) by Molecular Beam Epitaxy (MBE) for CMOS gate application. Epitaxial Gd2O3 films of different thicknesses have been deposited on Si (111) between 650°C~750°C. Electrical characterizations reveal that the sample grown at the optimal temperature (700°C) presents an equivalent oxide thickness (EOT) of 0.73nm with a leakage current density of 3.6×10-2 A/cm2 at |Vg-VFB|=1V. Different Post deposition Annealing (PDA) treatments have been performed for the samples grown under optimal condition. The Gd2O3 films exhibit good stability and the PDA process can effectively reduce the defect density in the oxide layer, which results in higher performances of the Gd2O3/Si (111) capacitor.

Osteoblast proliferation on hydroxyapatite coated substrates prepared by right angle magnetron sputtering

The preparation of hydroxyapatite (HA) coatings via a versatile right-angle magnetron sputtering (RAMS) approach for use as a biomaterial has recently been reported. RAMS coatings show some advantages over conventionally sputtered films in that room temperature deposition yields nanocrystalline and nearly stoichiometric HA coatings under appropriate conditions, thereby avoiding the troublesome post deposition annealing treatment. In this article, we present an exploratory study of the biocompatibility of RAMS HA coatings deposited on metallic substrates. RAMS HA coatings with a thickness around 500nm were prepared on various substrates. X-ray diffraction (XRD) analysis showed that the as-deposited HA coatings were polycrystalline with some strongly preferred orientations. Atomic force microscopy (AFM) results showed that the coatings were rather smooth with surface roughness on the order of 10 nm. X-ray photoelectron spectroscopy (XPS) confirmed that the surface chemistry was nearly stoichiometric. To study the biocompatibility of these coatings, murine pre-osteoblastic MC3T3-E1 cells were seeded onto various substrates. Cell density counts using fluorescence microscopy showed that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. Additionally, in preliminary studies the influence of Zn, Mg, and Al incorporation in the HA crystal lattice on the in vitro behavior was also evaluated. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.

Enhanced fraction of coupled Er in silicon-rich silicon oxide layers grown by magnetron co-sputtering

The structural and optical emission properties of Er-doped silicon-rich silica layers containing 10 21 at cm −3 of erbium are studied as a function of deposition conditions and annealing treatment. Magnetron co-sputtering of three confocal targets (Si, SiO 2 and Er 2O 3) under a plasma of pure argon was used to deposit the layers at 500 °C. The silicon excess was varied in the layers in the range 7–15 at% by monitoring the power applied on Si cathode. The as-grown samples were found significantly emitting at 1.54 μm under non-resonant excitation. A maximum Er emission was observed after annealing at a moderate temperature (600 °C) for any amount of Si excess, with a highest 1.54 μm photoluminescence (PL) from the sample containing 13 at% of Si. While no nanocrystals were observed in the samples annealed at 600 °C, the sensitizers might, therefore, consist in ‘atomic’ scaled entities (Si agglomerates, for example) considered in recent similar work. The comparison of the emission features of our “best” sample and their counterparts reported so far, shows that the approach used this work allows to increase the fraction of the Er 3+ ions coupled to Si sensitizers from 3% up to 12% of the total Er content.

Long lifetime and efficient emission from Er 3+ ions coupled to Si nanoclusters in Si-rich SiO 2 layers

Reactive magnetron co-sputtering of two confocal SiO 2 and Er 2O 3 cathodes in argon–hydrogen plasma was used to deposit Er-doped Si-rich SiO 2 layers. The effects of the deposition conditions (such as RF power applied on each cathode and total plasma pressure) and annealing treatment (temperature and duration) on structural, compositional and photoluminescence (PL) properties of the layers were examined. It was found that a significant enhancement of both Er 3+ PL intensity and emission lifetime up to 9 ms have been reached through monitoring of the conditions of both deposition process and annealing treatment. The effective absorption cross section and the fraction of Er ions coupled to Si clusters were analyzed. It was shown an increase of the fraction of Er 3+ ions coupled to Si up to 11%.

Charge trapping behavior of SiO 2-Anodic Al 2O 3–SiO 2 gate dielectrics for nonvolatile memory applications

In this study, Anodic Aluminum Oxide (AAO) is used as the storage layer instead of silicon nitride in a silicon–SiO 2–Si 3N 4–SiO 2–Silcon (SONOS) structure in flash memory devices and a double I– V method is utilized to investigate its charge trapping behavior on SiO 2–Al 2O 3–SiO 2 (OAO) triple stacks. The experimental results show that more initial charge density can be charged into the centroids of neutral charge trapping sites using post deposition annealing (PDA) treatment in OAO triple stacks. Under stress bias testing, OAO triple stacks exhibit a larger shift of threshold voltage than do ONO type devices. The trap energy levels of the bulk electron traps in high k AAO materials were determined. The initial trapping charges are produced during the fabrication process and are changed into centroids of neutral charge trapping sites after PDA treatment, which are responsible for charge trapping/de-trapping during programming/erasing. All devices show that the trapping centroid moves to the top oxide with an increase of stress time.

Post deposition annealing temperature effect on silicon quantum dots embedded in silicon nitride dielectric multilayer prepared by hot-wire chemical vapor deposition

The preparations of the 20-period of a Si quantum dot (QD)/SiN x multilayer in a hot-wire chemical vapor deposition (HWCVD) chamber is presented in this paper. The changes in the properties of Si-QDs after the post deposition annealing treatment are studied in detail. Alternate a-Si:H and SiN x layers are grown in a single SiN x deposition chamber by cracking SiH 4, and SiH 4 + NH 3, respectively at 250 °C. The as-deposited samples are annealed in the temperature range of 800 °C to 950 °C to grow Si-QDs. All the samples are characterized by confocal micro Raman, transmission electron microscope (TEM), and photoluminescence (PL) to study the changes in the film structures after the annealing treatment. The micro Raman analysis of the samples shows the frequency line shifting from 482 cm − 1 to 500 cm − 1 indicating the Si transition from an amorphous to a crystalline phase. The TEM micrograph inspection indicates the formation of Si-QDs of size 3 to 5 nm and a density of 5 × 10 12/cm 2. The high resolution TEM micrographs show an agglomeration of Si-QDs with an increase in the annealing temperature. The PL spectra show a peak shifting from 459 nm to 532 nm with increasing the annealing temperature of the film.

Intrinsic Amorphous Silicon (a-Si:H) Thin Film Prepared by Using Remote Plasma Chemical Vapor Deposition Method and Used as a Passivation Layer for a Heterojunction Solar Cell

The hydrogenated amorphous silicon (a-Si:H) lms used as intrinsic passivation layers were prepared using the radio-frequency remote-plasma chemical vapor deposition method under various deposition conditions for application to heterojunction solar cells. Their characteristics, such as their structural properties and carrier lifetimes, were investigated. When the substrate temperature was set to 250 C, the optimal deposition gas ratio (rH = SiH4/H2) and the RF power were 1/15 and 80 W, respectively. Furthermore, to improve the passivation e ect, we performed an annealing treatment. The highest improvement was displayed at an annealing temperature of 250 C. In the FT-IR analysis, the Si-H2 stretching mode, which means defects in the lms, was shifted to Si-H stretching mode, which means a good quality lm, after annealing treatment. Moreover, the highest carrier lifetime was 1.5 ms, which is higher value than the bulk lifetime of 900 s. From these results, we conclude that a combination of optimal deposition conditions and annealing treatment is essential to improve the surface and bulk passivation.

Towards an enhanced coupling between the Er ions and Si nanoclusters

The reactive magnetron co-sputtering of two confocal SiO 2 and Er 2O 3 cathodes in argon–hydrogen plasma was used to deposit Er-doped Si-rich-SiO 2 layers. The effects of deposition conditions (such as hydrogen rate and substrate temperature) and annealing treatment (temperature and time) on the structural, compositional and photoluminescence (PL) properties of the layers were examined. An enhancement was observed of both Er 3+ PL emission and Er 3+ lifetime at 1.54 μm in comparison with their counterparts for the best samples reported so far. It was shown that a lifetime as high as 9 ms can be reached, with comparable PL intensities for resonant and non-resonant excitation lines. The effective cross-section and the fraction of Er ions coupled to Si clusters are analyzed.

Crystallization and magnetic hardening of SmCo thin films

Hard magnetic thin films preparation is a key issue on the development of new micro-electro-mechanical systems. Vapour phase preparation techniques are desired because they are more easily incorporated into the typical microfabrication techniques. In this work we present the deposition of SmCo thin films by both magnetron sputtering (MS) and pulsed laser deposition (PLD). Thin films prepared by MS at temperatures below 400°C are amorphous and present soft magnetic properties, whereas those deposited at 450°C are nanocrystalline and present hard magnetic properties with a well defined in plane easy axis. The PLD prepared samples are nanocrystalline, but present soft magnetic properties. In both cases, post deposition annealing treatments have been successfully carried out, giving rise to a maximum coercivity of 2.7T.

Effect of Post Deposition Annealing Temperature on the Optoelectrical Property of ITO Thin Films Prepared by Magnetron Sputter Type Negative Metal Ion Source

Transparent conducting indium tin oxide (ITO) thin films were deposited on glass substrates by magnetron sputter type negative metal ion source (MSNIS) using ITO target and then the effect of post deposition annealing temperature on the optoelectrical property of ITO film has been investigated. The resistivity and optical transmittance of ITO films that prepared at 70°C (without intentional substrate heating) with optimized deposition condition reached at 6.2×10-4 cm and 80%, respectively. As increasing post deposition annealing temperature, a rapid decrease is observed in the resistivity. The lowest resistivity of 1.7×10-4 cm and the highest optical transmittance of 83% were obtained at the post annealing temperature of 300°C. From the XRD and SEM measurements, the increment of the optical transmittance and conductivity by post deposition annealing treatment is attributed to the enhanced crystallinity of the ITO film.