Temperature Annealing In Air Research Articles

Oxidation Behavior, Insulation Resistance, and Permeability of FeSiCr Alloys for Multilayer Inductors

FeSiCr alloys are used as soft magnetic materials for power multilayer inductors. The alloys are typically annealed at intermediate temperatures in air during inductor fabrication to form an insulating chromium oxide layer around the alloy particles. The variation of the annealing temperature between 700 °C and 900 °C in air, and, for the first time, the variation of the oxygen partial pressure during annealing at 900 °C are studied, and their effects on the alloy’s oxidation behavior, phase formation, insulation resistance, and permeability are demonstrated. The chromium oxide content increases up to about 12 wt% with annealing temperature in air, whereas it decreases to 8.2 wt% after annealing at 900 °C and 0.001% O2. The observed mass changes during annealing confirm the various tendencies towards oxidation. This oxidation behavior is reflected in an increase in the insulation resistance with annealing temperature or in a resistance reduction with decreasing oxygen partial pressure. The permeability decreases from µ = 22 after annealing at 700 °C to µ = 18.5 at 900 °C in air. The reduction of pO2 during annealing at 900 °C leads to an increase in permeability up to µ = 22.5 at pO2 = 0.001% O2. The results can be used to design cofiring strategies using reduced oxygen partial pressure for new composite multilayer inductive components consisting of FeSiCr- and ferrite layers in combination with silver metallization.

(Digital Presentation) Liquid-Metal-Printed Ultra-Thin ITO-Thin-Film Transistor

Indium oxide is one of the promising materials for the n-channel layer for high-mobility oxide-TFT because of its high electron mobility characteristics due to the nature of spatially spread-In 5s orbital. However, excess carrier electrons in In-based channels cancel field-effect gate modulation and causes the formation of a short depletion layer. Moreover, it is challenging to reduce the electron density without the degradation of electron transport. Therefore, developing fully-depletion operated TFT using an ultra-thin channel is a straightforward strategy to demonstrate the high potential of In-based materials for TFT applications.In this work, we developed an ultra-thin tin-doped Indium oxide (ITO) channel (~ 1.9 nm-thick.) and demonstrated a fully-depleted ITO-TFT exhibiting high mobility of 27 cm2/Vs. The ITO channel was grown by a cost-effective vacuum-free liquid-metal-printing route at the maximum process temperature of ~ 200 oC in an ambient atmosphere. Post-thermal annealing in air made significant improvement of device characteristics originating from the reduction of shallow acceptor-like in-gap defects in the ITO channels, and high-performance n-channel ITO-TFT with a large on/off-current ratio of 109 and a sharp threshold slope was achieved. By controlling air-annealing temperature, we also successfully fabricated both enhancement and depletion-mode devices and developed a full signal swinged-oxide-NMOS inverter composed of a depletion-load structure.

Comprehensive microstructural and optical characterization of the thermal stability of aluminum-titanium oxynitride thin films after high temperature annealing in air

The thermal stability of two AlyTi1-y(OxN1-x) layers prepared by cathodic vacuum arc deposition with different oxygen content was studied after high temperature annealing of the samples in air. These layers were designed to be part of solar-selective coating (SSC) stacks. Compositional and microstructural characterization of the thin films was performed before and after the thermal treatment by elastic recoil detection (ERD), transmission electron microscopy, and Raman spectroscopy. AlyTi1-yN sample was stable after 2 h of annealing at 450 °C. Initial stages of the formation of a surface oxide layer after annealing at 650 °C were observed both by ERD and Raman analysis. Contrarily, no changes were found after 2 h annealing treatment either at 450 and 650 °C in the composition and microstructure of AlyTi1-y(OxN1-x) sample. In both samples, the formation of a surface anatase TiO2 film was reported after 2 h annealing at 800 °C. These compositional and microstructural changes were correlated with the optical properties determined by spectroscopic ellipsometry. A transition from metallic to dielectric behavior with increasing annealing temperature was observed. These results complete the durability studies on the designed SSC based on AlyTi1-y(OxN1-x) materials, confirming that these stacks withstand breakdown at 600 °C in air.

Indium tin oxide obtained by high pressure sputtering for emerging selective contacts in photovoltaic cells

This article studies the physical and electrical behavior of indium tin oxide layers (ITO) grown by an unconventional technique: High Pressure Sputtering (HPS), from a ceramic ITO target in a pure Ar atmosphere. This technique has the potential to reduce plasma induced damage to the samples. The aim is to obtain, at low temperature via HPS, good quality transparent conductive oxide layers for experimental photovoltaic cells with emerging selective contacts such as transition metal oxides, alkaline metal fluorides, etc. We found that the resistivity of the films was strongly dependent on Ar pressure. To obtain device-quality resistivity without intentional heating during deposition a pressure higher than 1.0 mbar was needed. These films deposited on glass were amorphous, presented a high electron mobility (up to 45 cm2V−1s−1) and a high carrier density (2.9 × 1020 cm−3 for the sample with the highest mobility). The optimum Ar pressure range was found at 1.5–2.3 mbar. However, the resistivity degraded with a moderate annealing temperature in air. Finally, the feasibility of the integration with photovoltaic cells was assessed by depositing on Si substrates passivated by a-Si:H. The film deposited at 1.5 mbar was uniform and amorphous, and the carrier lifetime obtained was 1.22 ms with an implied open circuit voltage of 719 mV after a 215 °C air anneal. The antireflective properties of HPS ITO were also demonstrated. These results show that ITO deposited by HPS is adequate for the research of solar cells with emerging selective contacts.

Dysprosium stannate (Dy2Sn2O7)-nanostructured thin films prepared by spray pyrolysis technique: effect of dysprosium and annealing on the physical properties

In this paper, dysprosium stannate-nanostructured thin films (Dy2Sn2O7) were deposited by spray pyrolysis method on fused silica substrates at T = 480 °C. A solution of 0.1 molar tin(IV) chloride pentahydrate (SnCl4⋅5H2O) and dysprosium(III) nitrate with mole ratios of [Dy/Sn] % = 10, 30, 50, 70, and 100% was used to prepare dysprosium stannate-nanostructured thin films (Dy2Sn2O7) by spray pyrolysis method. Then, the effect of Dy-content and annealing temperature in air at T = 500, 600, 1100 and 1200 °C, on structural conversion and optical properties were investigated for these films. The X-ray diffraction (XRD) patterns indicated that the dominant phase above T = 1100 °C is pyrochlore phase of dysprosium stannate. The field emission scanning electron microscopy (FE-SEM) images showed the formation of nanocrystals of dysprosium stannate with pyrochlore structure. The FE-SEM images show that the surface morphologies of as-prepared films are in the form of cubic nanocrystals before annealing and nano-polyhedral as agglomerated after annealing at T = 1200 °C. The results of UV–Vis analysis indicated that with increasing the Dy-content and annealing at T = 1200 °C, optical transmittance and bandgap was increased. The optical bandgap for ratios of [Dy/Sn] = 50 and 100% were obtained 2.65 and 2.76 eV, respectively, after annealing at T = 1200 °C.

Semi-transparent Schottky junction solar cell based on evaporated CdSe thin films: Influence of post-deposition air-annealing

FTO/CdSe/Al semi-transparent Schottky junction solar cells were fabricated by evaporating 300 nm CdSe thin films onto the FTO electrode and forming the Schottky junction by evaporation the aluminum onto the absorber layer. The performance of the samples was optimized by air-annealing the absorber layer prior to the evaporating of the top electrode. Also, the structural, optical and electrical properties of thermally evaporated CdSe thin films were investigated as a function of post-deposition air-annealing temperature. The surface morphology of the specimens was studied using field emission scanning electron microscope (FE-SEM) analysis. X-ray diffraction (XRD) analysis revealed the hexagonal structure of the samples. The crystallite size, micro-strain and dislocation density of CdSe thin films were evaluated using XRD patterns. The transmittance spectra in the wavelength range of 400−2500 nm were measured and then used to study other optical parameters. The optical energy band gap was decreased with air-annealing from 2.17 eV to 1.69 eV. It is observed that complex refractive index, relative density, complex dielectric constant and electrical polarizability of specimens were increased by air-annealing. Electrical conductivity and the photovoltaic efficiency of FTO/CdSe/Al Schottky barrier devices were improved by thermal annealing and annealed sample at 300 °C shows the best performance (η = 1.53 %). Obtained results show that CdSe thin films are a promising candidate to use as an absorber layer in semi-transparent solar cells and colorful photovoltaic windows.

Optical and surface properties of CdSe thin films prepared by sol-gel spin coating method

In this work, L-cysteine capped CdSe nanocrystals thin films were grown on glass substrate by using spin-coating method. The annealing temperature effect on structural, morphological, and optical properties of CdSe thin film is investigated by X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Atomic force microscopy (AFM), UV–Vis and photoluminescence (PL) techniques. XRD analysis showed crystallization and phase transformation of CdSe thin films from cubic (Zinc Blende, β-CdSe) to hexagonal (Wurtzite, α-CdSe) structure are obtained after air-annealing at 250 °C during 30 min. DSC analysis showed the exothermic peak in the range of 170–225 °C, indicating the structural phase transformation of CdSe thin film. AFM analysis exhibited a change in the surface roughness of thin films and the shape of CdSe nanoparticles from hemispherical nanocrystals into microrods as a function of annealing temperature. The surface and volume energy loss (VELF and SELF) functions show different dependences on the incident photon energy for the CdSe films in the energy range 1.5–4 eV as a function of air-annealing temperature. The dispersive optical parameters such as refractive index (n), extinction coefficient (k), and the dielectric constants were found to vary with the annealing temperature. PL measurements showed that the increase in the annealing temperature up to 200 °C results an improvement in the crystalline quality of the CdSe thin film, a decrease in their optical band gap, and an enhancement in the PL peak intensity.

Control of Electrical and Optical Parameters of Humidity Sensors Active Elements Based on Tin Oxides Films with Variable Composition

The aim of this work is development of technique for synthesis of tin oxides films with various stoichiometric composition, characterized by high electrical conductivity and light transmittance in the UV and visible range of the electromagnetic spectrum, for their further application as humidity and gas sensors, as well as electrodes for electro-and photocatalytic converters.Nonstoichiometric SnO/SnO2 /SnO2−δ films were synthesized by reactive magnetron sputtering of tin onto glass substrates in argon plasma with oxygen addition and with subsequent thermal oxidation of the formed layers in air. To change the structural, optical, and electrical properties of the films and to find out the optimal synthesis parameters, the oxygen content during the deposition process and the annealing temperature in air were varied in the range of 0–2 vol. % and of 200–450 °C, respectively. The characterization of the films was carried out using a 4-probe method for measuring the electrical resistance, X-ray diffraction, and optical spectroscopy of light transmission.As a result of a comprehensive analysis of the structural, optical and electrical properties of the films, it was found that the optimal synthesis parameters to obtain the most transparent and conductive coatings promising for use as humidity, gas sensors and in photovoltaic devices are the following: oxygen content in argon plasma during sputtering process is ≈ 0,8–1,2 vol. %, the annealing temperature in air is ≈ 350–375 °C. In this case a polycrystalline film with high electrical conductivity and high transmittance in the visible and UV regions of the electromagnetic spectrum with prevailing of tin dioxide phase with structural defects (oxygen vacancies) is formed.

Application of Taguchi method to optimize the sol–gel dip-coating process of the semiconductor Cu2ZnSnS4 with good optical properties

This paper presents the optimal configuration of parameters for the elaborated Cu2ZnSnS4 (CZTS) absorber layer, using the sol–gel method associated with dip-coating technique on ordinary glass substrates. Taguchi design of experiments with L27 (38) orthogonal array, a signal-to-noise (S/N) ratio, and an analysis of variance (ANOVA) were used to determine the best optical properties for photovoltaic applications (optical bandgap energy) of CZTS thin films. Eight factors named annealing temperature, Cu/(Zn+Sn) ratio, Zn/Sn ratio, S/metal ratio, number of pre-annealing and dip coating, dip-coating cycle, annealing time, and dip-coating speed were chosen. To conduct the tests, we apply Taguchi method; three levels were fixed for each factor. The most important factors of the deposition approach on the optical properties of the fixed as-synthesized CZTS films were determined. The analysis of the obtained results indicated that the important parameters are the Zn/Sn ratio and annealing temperature in air by employing Taguchi approach. A validation test is also carried out to check whether the found optimal combinations of the parameter are correct. CZTS thin-film synthesis with optimal conditions has been characterized, using an X-ray diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), UV–visible spectrophotometer, and four-point probe method. XRD data show a kesterite structure with a preferential orientation along the (112) plan; UV–visible spectrophotometer indicated that the bandgap energy of the CZTS thin film is 1.51 eV and a cross section showed the suitable film thickness in the order of ~1.80 µm.

P-type SnO thin films prepared by reactive sputtering at high deposition rates

SnO is an ideally suitable p-type conductive material, with large hole mobility, and has attracted great interest in connection with next-generation electronic applications. In the present work, tin oxide (SnOx) thin films were deposited on unheated soda lime glass substrates by reactive DC sputtering from a pure Sn target. The structural, optical and electrical properties of the films were analysed as a function of the oxygen partial pressure in the sputtering atmosphere and of the post-deposition annealing temperature in air. A structural analysis was carried out using Raman spectroscopy and X-ray diffraction. Optical and electrical characterizations were performed using photo-spectrometry and Hall effect measurements, respectively. The films grown at room temperature and low oxygen pressures reached high deposition rates of above 45 nm/min, showing poorly crystalline SnO and low transparency. Subsequent heating to 350 °C allowed to achieve a more crystalline tetragonal SnO with an average visible transmittance of 65%, a p-type conductivity of 0.8 S/cm, and a hole mobility of 3.5 cm2/(V s).

Doping Graphene Oxide Aerogel with Nitrogen during Reduction with Hydrazine and Low Temperature Annealing in Air

The presence of nitrogen is revealed via elemental analysis and X-ray photoelectron spectroscopy in graphene oxide aerogel annealed in air. It is estimated that a substantial amount of nitrogen emerges in samples at an annealing temperature of 125°С. The concentration of nitrogen in the aerogel is greatest (0.17 wt %) at an annealing temperature of 225°С. The concentration of nitrogen reaches 3 wt % upon the reduction of aerogel in hydrazine vapor. N1s spectrum of aerogel reduced with hydrazine is approximated by three peaks (399.5, 401.3, and 403.6 eV). Nitrogen is present in only the two states that correspond to the N1s photoelectron peaks characterized by bond energies of 399.7 and 401.2 eV, respectively, in air-annealed aerogel.

Influence of calcination temperature on the photocatalytic performance of the hierarchical TiO2 pinecone-like structure decorated with CdS nanoparticles

Herein, a novel hierarchical TiO2 pinecone-like structure (TPS) has been successfully fabricated for the first time by self-assembling anodic oxidation methods on the Ti plate. Then it was constructed that a series of CdS-TPS nanocomposites with different cycles CdS modifying by a successive ionic layer adsorption and reaction (SILAR) after different temperature annealing in air. The structures and properties of the CdS-TPS were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Current-voltage (I-V), ultraviolet-visible (UV–vis/DRS). The results shown that the optical properties of the CdS-TPS could be rationally tailored by adjusting the CdS-modified cycles and annealing temperature, which significantly enhanced photocatalytic activity. To be used in photocatalytic organic pollutant removal after optimizing both the CdS modification cycles and annealing temperature. The 15-CdS-TPS-500 °C exhibited significantly improved photocatalytic activities of methyl orange (MO) degradation under simulated sunlight irradiation. With 180 min, 85% of the MO (0.05 mM/L, 5 mL) was photodegraded and its kinetic constant reached to 0.0104 min−1, which is the 3.0 times and 3.6 times quicker than that of 5-CdS-TPS-500 °C and 15-CdS-TPS-0 °C, respectively. This could be ascribed to the result of the synergy effects of the suitable quantity of CdS nanoparticles modifier, the special surface structure, excellent crystallinity, higher electrical conductivity, and band structure matching. The possible photocatalytic mechanism of the CdS-TPS sample is investigated as well.

Down-shifting emission by charge transfer band in porous silicon infiltrated with Eu3+ and Gd3+ ions

Down-shifting emission properties of europium (Eu3+) and gadolinium (Gd3+) ions incorporated in porous silicon (PS) layers are presented. Different samples were prepared by electrochemical etching of p+-type crystalline silicon wafers followed by simple impregnation with rare earth ions from nitrate solutions of europium and gadolinium and subsequent high temperature annealing in air. The samples exhibited room temperature photoluminescence (PL) and the excitation spectra present a wide excitation band around 233 nm which can be associated to the charge transfer band transitions. This band is attributed to O2−(2p)→Eu3+(4f) ligand-to-metal charge transfer. The down-shifting emission for Gd+3:Eu3+ was analyzed by a simple rate equation model to study the interaction between the O2− ions and Eu3+ ions. The exact solution of this model agrees very well with the experimental results.

Annealing temperature dependence of structural, optical, and thermal properties of CdSe thin films grown on porous anodic alumina

In this study, cadmium selenide (CdSe) were synthesizd by a chemical route process using l-cysteine (l-cyst) as a ligand, cadmium acetate as a Cd source and Na2SeO3 as a Se precurseur. CdSe nanocrystals were embedded in porous anodic alumina (PAA) layer by the chemical bath deposition (CBD) method. The influence of annealing temperature in air-atmosphere from 150 to 350 °C on the microstructural, optical properties, and thermal conductivity of CdSe in PAA template has been studied by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, UV–Vis and photothermal deflection (PTD) techniques. The annealing temperature at 300 and 350 °C resulted in a considerable change in the surface morphology of CdSe film on the PAA layer, from a nonhomgeneous CdSe clusters into microrods array with a pyramidal ends. Raman spectroscopy measurements show an enhancement in the crystallinity of CdSe film on PAA layer and an increase of the average radius size of the nanocrystallites from 2.41 to 2.78 nm with the increase of air-annealing temperature. The optical reflectivity result of CdSe on PAA template showed that the crystal quality was significantly improved after the annealing step, bringing about an enhancement in optical absorption and a decrease in bandgap energy. The thermal conductivity Kth was studied via PTD technique, and the Kth increase was depicted with thermal treatement from 4.40 to 5.22 W M−1 K−1.

Sputtered Inx(O,S)y Buffer Layers for Cu(In,Ga)Se2 Thin-Film Solar Cells: Engineering of Band Alignment and Interface Properties.

We propose a simple approach to engineering the sputtered Inx(O,S)y/Cu(In,Ga)Se2 heterojunction, in terms of band alignment and interface properties. The band alignment was tailored by tuning the base pressure of the sputtering deposition to incorporate oxygen into deposited In2S3 layers (termed as Inx(O,S)y). The interface properties were improved by optimizing the air-annealing temperature on Inx(O,S)y/Cu(In,Ga)Se2 stacked layers. Increasing the base pressure raises the O/(S + O) ratio contained in deposited Inx(O,S)y films and thus widens the band gaps. This could effectively tailor the conduction band offset (ΔEC) at the Inx(O,S)y/Cu(In,Ga)Se2 interface from a cliff (-0.25 eV) to a nearly flat band (0.07 eV) alignment. On the other hand, the extra air annealing at 235 °C did not significantly change the band alignment but did ameliorate the interface properties by reducing the Cu content at the Cu(In,Ga)Se2 surface and diminish the interface defect density induced by sputtering damages. The former might enhance the type of inversion and increase the hole barrier at the interface, preventing the detrimental recombination behavior. The latter could effectively strengthen the junction quality. Consequently, our approach substantially enhances the cell efficiency from 2.30% to 11.04%.

A mixed mechanochemical-ceramic solid-state synthesis as simple and cost effective route to high-performance LiNi0.5Mn1.5O4 spinels.

The implementation of high potential materials as positive electrodes in high energy Li-ion batteries requires to develop scalable and smart synthetic routes. In the case of the LiNi0.5Mn1.5O4 (LNMO) spinel material, a successful preparation strategy must drive the phase formation in order to obtain structural, morphological and surface properties capable to boost performances in lithium cells and minimize the electrolyte degradation. Here we discuss a novel simple and easily scalable mechanochemical synthetic route, followed by a high temperature annealing in air, to prepare LMNO materials starting from oxides. A synergic doping with chromium and iron has been incorporated, resulting in the spontaneous segregation of a CrOx-rich surface layer. The effect of the annealing temperature on the physico-chemical properties of the LMNO material has been investigated as well as the effect on the performances in Li-cells.

Origin of polychromatic emission and defect distribution within annealed ZnO nanoparticles

Defects distribution in ZnO nano-particles is introduced by high temperature annealing in air and corresponding visible emission are comprehensively analyzed. Grain size initially increases with increasing annealing temperature until 800°C and decreases after that. Higher temperature annealing alters defect distribution and initiates formation of OZn (Zinc at oxygen site). Formation of OZn, and presence of conventional defects is confirmed by Electron Paramagnetic Resonance spectra. Spatial distribution of polychromatic emission centers in annealed sample is estimated by diffusion mediated growth and confirmed by florescence imaging. Blue emission centre is found to be located on surface of particle/grain which gets modified by surface capping using PEG and PVA. These visible emissions exhibit strong excitation dependence, and can be excited below the bad gap energy. Based on XRD, EPR, emission by low energy excitation, and florescence imaging schematic of defect distribution within particle/grain and their corresponding emission is proposed.

Structural, luminescent properties and chemical state analysis of YAG:Ce nanoparticle-based films

Y3Al5O12: Ce (YAG:Ce) nanoparticles need annealing treatment at high temperature to transform the amorphous precursors to crystalline YAG phase. However, little is known about Ce chemical state analysis and photoluminescence (PL) properties of YAG:Ce nanoparticles with the different annealing temperatures and atmospheres. In this paper, amorphous nanoparticle-based YAG:Ce films, prepared by electron beam deposition technique on fused silica substrates, have been annealed at different conditions. Ce3+, Ce4+ states and Ce3+/Ce4+ atomic ratio have been distinctly separated and calculated by X-ray photoelectron spectroscopy (XPS). Combined Ce3+/Ce4+ atomic ratio with the microstructures, the Ce chemical state modification and PL properties of YAG:Ce films with different annealing treatments have been investigated throughout. Low temperature annealing in air can cause oxidation of Ce3+, higher temperature (≥750°C) annealing in air can cause partial reduction of Ce4+ due to the high-temperature pyrolysis. In this paper, value of Ce3+/Ce4+ is the maximum after 850°C annealing in H2, and YAG:Ce film annealed in H2 has the maximum luminous intensity, which could be proposed to the increased Ce3+ content. According to the systematical research and analysis, one can find that the Ce3+ content controls the luminescence efficiency. This paper provides a feasible approach to produce YAG:Ce nanoparticle-based films for the practical applications, and provides the understanding about YAG:Ce luminescent properties.

Effect of air-annealing on the morphological, microstructural and optical properties of CdSe NCs grown into porous anodic alumina template

In this work, cadmium selenide nanocrystals (CdSe NCs) were embedded into porous anodic alumina (PAA) template by simple immersion in aqueous solution containing l-cysteine (Cys) functionalized CdSe NCs and water. The prepared samples were heat treated at different temperatures between 150 and 300°C during 30min under air. The effect of thermal treatment under air on the CdSe NCs/PAA has been shown from morphological, microstructural and optical studies. Several characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) spectroscopy were used to investigate the surface morphology and microstructural properties of CdSe nanoparticles on the PAA template as function of air-annealing temperature. XRD study shows the transformation phase of deposited CdSe nanoparticles on the PAA template from cubic structure to hexagonal structure at 300°C. The morphology of CdSe nanorods array which are into the PAA surface were exhibited by AFM scan. Optical properties of CdSe NCs into PAA have been studied at different air-annealing temperatures using optical absorption and photoluminescence (PL) spectroscopy. The results showed that the crystal quality was significantly improved with the annealing temperature increase, bringing about an enhancement in PL and a decrease in optical band gap from 2.44 to 2.2eV exhibiting a red shift.

Growth of silicon quantum dots by oxidation of the silicon nanocrystals embedded within silicon carbide matrix

A moderately low temperature (≤800 °C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (μc-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of Tv = 525 °C. The samples were then stepwise annealed at different temperatures Ta in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the μc-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (DXRD) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in Ta from 250 °C to 800 °C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV.