Silica Layer Research Articles

Optimizing phosphorus-doped polysilicon in TOPCon structures using silicon oxide layers to improve silicon solar cell performance

Tunnel Oxide Passivated Contact (TOPCon) technology is one of the most influential and industrially viable solar cell technologies available today. Improving the quality of passivation contact has become a central focus of current research. Although the conventional monolayer polycrystalline silicon method is highly effective in TOPCon solar cells, it is limited by doping inhomogeneity, which impairs the passivation and electrical properties, and the cell's photovoltaic conversion efficiency remains suboptimal. To address this issue, this study investigates the deposition of two layers of silicon oxide and two layers of in-situ doped phosphorus amorphous silicon, termed double poly-Si/SiOx structures, on n-type silicon wafers using plasma-enhanced chemical vapor deposition (PECVD). The effectiveness of the structure was confirmed through various characterization techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Key findings indicate that the double-polysilicon structure significantly enhances the uniformity of phosphorus doping, improving the carrier lifetime of the cell and reducing the contact resistance. As a result, the average efficiency in the final production stage has a conversion efficiency gain of 0.23 % over the baseline group. This study underscores the potential of this PECVD methodology to advance the fabrication of high-efficiency solar cells by providing significant improvements in passivation, doping uniformity, and overall cell performance.

Treatment of Paracetamol in Water with Different Salinities over Powder and Supported TiO2 and ZnO Photocatalysts

ABSTRACT. Paracetamol's (PCT) Paracetamol's (PCT) presence in water bodies poses a risk to both aquatic life and humans. This study aims to examine the effect of salinities on PCT removal in water using powder and supported photocatalysts. ZnO powder is a superior photocatalyst to TiO2, where the rate constant can be 18 times higher. Salinity boosted the PCT removal up to 2.7 times for TiO2 at lower concentrations but decreased the PCT removal for TiO2 and ZnO at higher values. Immobilizing the powder photocatalysts on a nonwoven polyester support (NPS) dropped the photocatalytic activity, especially for ZnO, whose performance was 36 times lower than its powder counterpart. The passivation of the photocatalysts by the silica binder necessary for attaching the photocatalyst to the support can be linked to the decline in the performance of TiO2 and ZnO composites. The silica and TiO2 formed homogeneous layers on the NPS, unlike the silica and ZnO layers. High salinity reduced the performance of TiO2 composites by 20 times but showed no significant effect on ZnO composites. The performance of the ZnO composite was further reduced when real seawater was used as feed. Keywords: Titanium dioxide, zinc oxide, polyester, paracetamol, salinity.

Design of silver-zinc-nickel spinel-ferrite mesoporous silica as a powerful and simply separable adsorbent for some textile dye removal

Silver-zinc-nickel spinel ferrite was prepared by the co-precipitation procedure with the precise composition Ag0.1Zn0.4Ni0.5Fe2O4 for bolstering pollutant removal effectiveness while upholding magnetic properties and then coated with a mesoporous silica layer. The surface characteristics and composition of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 were confirmed using EDX, FT-IR, VSM, XRD, TEM, SEM, and BET methods. The surface modification of Ag-Zn-Ni ferrite with a silica layer improves the texture properties, where the specific surface area and average pore size of the spinel ferrite rose to 180 m2/g and 3.15 nm, respectively. The prepared spinel ferrite@mSiO2 has been utilized as an efficient adsorbent for eliminating methyl green (MG) and indigo carmine (IC) as models of cationic and anionic dyes from wastewater, respectively. Studying pH, Pzc, adsorbent dosage, dye concentration, and temperature showed that efficient removal of MG was carried out in alkaline media (pH = 12), while the acid medium (pH = 2) was effective for IC removal. Langmuir isotherm and pseudo-second-order kinetics were found to be good fits for the adsorption data. Both dyes were adsorbed in a spontaneous, endothermic process. A possible mechanism for dye removal has been proposed. The adsorbent was effectively recovered and reused.

Molecular Layering of an Additive Layer of Silicon Dioxide on Anodized Tantalum and Niobium Oxides

The results of studying the processes of formation of nanolayers of silicon oxide by the method of molecular layering (atomic layer deposition) on the surface of films of tantalum and niobium oxides obtained by electrochemical oxidation of the corresponding metals are presented. A study of the electrical strength of metal-dielectric-metal (MDM) structures based on tantalum and niobium oxides showed that the introduction of an additive dielectric layer (SiO2) can significantly increase the electrical strength of these structures.

Dynamic tunable and switchable broadband near-infrared absorption modulator based on graphene-hybrid metasurface

The integration of graphene with metasurfaces enables devices with remarkable dynamic tunability, propelling electromagnetic (EM) manipulations to new heights by transitioning from static to dynamic control. In this study, we theoretically investigate a broadband absorption modulator with dynamic tunability based on a graphene hybrid metasurface. The metasurface consists of a monolayer graphene sheet sandwiched between a square silver block and a silica layer. The excitation of the magnetic toroidal dipole (MTD) leads to a significant enhancement of graphene’s electromagnetic absorption. By arranging four blocks as a supercell to support multi-resonance, we achieve a broadband modulator spanning from 1000 to 1210 nm, with graphene absorption exceeding 57 %. Notably, there is no plasmonic hybridization among adjacent components within the super unit. By tuning the Fermi energy of graphene, narrow-band tunability can be achieved at any wavelength within the operation spectrum. Furthermore, the designed device exhibits a perfect modulation depth (∼100 %). We demonstrate the switchability of the proposed device by showcasing its ON/OFF status at representative wavelengths of 1205 nm, 1119 nm, and 1052 nm. Thus, the proposed graphene-based hybrid metasurface fulfills the requirements for broadband tunability and switchability, offering a high ON/OFF ratio, full modulation depth, and a small switch voltage gap. This design holds significant potential for future developments.

Significantly Enhanced Mechanical, Thermal, and Ablative Properties of the Lightweight Carbon Fabric/Phenol-Formaldehyde Resin/Siloxane Aerogels Ternary Interpenetrating Network.

Lightweight ablative thermal protection materials (TPMs), which can resist long-term ablation in an oxidizing atmosphere, are urgently required for aerospace vehicles. Herein, carbon fabric/phenol-formaldehyde resin/siloxane aerogels (CF/PFA/SiA) nanocomposite with interpenetrating network multiscale structure was developed via simple and efficient sol-gel followed by atmospheric pressure drying. The ternary networks structurally interpenetrating in macro-, micron-, and the nanoscales, chemically cross-linking at the molecular scale, and silica layer generated by in situ heating synergistically bring about low density (∼0.3 g cm-3), enhanced mechanical properties, thermal stability, and oxidation resistance, and a low thermal conductivity of 81 mW m-1 K-1. More intriguingly, good thermal protection with near-zero surface recession at 1300 °C for 300 s and remarkable thermal insulation with a back-side temperature below 60 °C at 20 mm thickness. The interpenetrating network strategy can be extended to other porous components with excellent high-temperature properties, such as ZrO2 and SiC, which will facilitate the improvement of lightweight ablative TPMs. Moreover, it may open a new avenue for fabricating multifunctional binary, ternary, and even multiple interpenetrating network materials.

Irinotecan-loaded magnetite-silica core-shell systems for colorectal cancer treatment

Colorectal cancer represents a worldwide spread type of cancer and it is regarded as one of the leading death causes, along with lung, breast, and prostate cancers. Since conventional surgical resection and chemotherapy proved limited efficiency, the use of alternative drug delivery systems that ensure the controlled release of cytostatic agents possess immense potential for treatment. In this regard, the present study aimed to develop and evaluate the efficiency of a series of irinotecan-loaded magnetite-silica core–shell systems. The magnetite particles were obtained through a solvothermal treatment, while the silica shell was obtained through the Stöber method directly onto the surface of magnetite particles. Subsequently, the core–shell systems were physico-chemically and morpho-structurally evaluated trough X-ray diffraction (XRD) and (high-resolution) transmission electron microscopy ((HR-)TEM) equipped with a High Annular Angular Dark Field Detector (HAADF) for elemental mapping. After the irinotecan loading, the drug delivery systems were evaluated through Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry and differential scanning calorimetry (TG-DSC), and UV–Vis spectrophotometry. Additionally, the Brunauer–Emmett-Teller (BET) method was employed for determining the surface area and pore volume of the systems. The biological functionality of the core-shells was investigated through the MTT assay performed on both normal and cancer cells. The results of the study confirmed the formation of highly crystalline magnetite particles comprising the core and mesoporous silica layers of sizes varying between 2 and 7 nm as the shell. Additionally, the drug loading and release was dependent on the type of the silica synthesis procedure, since the lack of hexadecyltrimethylammonium bromide (CTAB) resulted in higher drug loading but lower cumulative release. Moreover, the nanostructured systems demonstrated a targeted efficiency towards HT-29 colorectal adenocarcinoma cells, as in the case of normal L929 fibroblast cells, the cell viability was higher than for the pristine drug. In this manner, this study provides the means and procedures for developing drug delivery systems with applicability in the treatment of cancer.

Mechanochemical exfoliation of sugar-assisted boron nitride nanosheets for achieving superlubricity and wear distinction

Boron nitride nanosheets (BNNS) possess extensive potential applications across various fields. However, their limited dispersibility in liquids constrains their effectiveness as lubricating additives. In this study, a streamlined sugar-assisted mechanochemical exfoliation technique was employed to concurrently exfoliate and functionalize BNNS. This approach enabled the covalent grafting of sucrose molecules onto BNNS, enhancing their dispersion in water. The application of water containing sucrose-modified BNNS (S-BNNS) facilitated an ultralow coefficient of friction (COF = 0.001) at the Si₃N₄-Si₃N₄ interface. Additionally, using S-BNNS nanosheets as lubricating additives in water achieved superlubricity with a significant surface roughness (Ra ≤120 nm). We explored the correlation between surface roughness and superlubricity, revealing that tribological performance was enhanced by the formation of a tribofilm composed of S-BNNS and a silica layer at the interface through tribochemical reactions. The exceptional anti-wear properties and significantly reduced shear strength of S-BNNS within the tribofilm substantially contributed to achieving the ultralow COF, thus enhancing lubrication performance.

SYNTHESIS AND CHARACTERISTICS OF ZnS NANOWIRES

The creation of a nanoporous silicon dioxide layer in the a-SiO2/Si-n structure was accomplished by irradiation with xenon ions at a cyclotron and then chemical etching with an aqueous solution of hydrogen fluoride with the addition of palladium. The truncated cone-shaped nanopores had diameters ranging from 486 to 509 nm. Then ZnS nanowires synthesized by electrochemical deposition (ECD) method, depending on the voltage at the electrodes of the electrolytic cell and as a result zinc sulfide nanowires with cubic structure and spatial symmetry group F-43m (216) were obtained. The sample is characterized by (111), (200), (220), (331) (311) planes, respectively, which is in good agreement with the cubic phase of ZnS. The charge-voltage characteristics (CVC) of ZnS showed that an n-type conductivity semiconductor was formed. Measurements of the photoluminescence (PL) spectra of ZnS were recorded on a CM 2203 spectrofluorimeter. The PL spectra were recorded in the range of 250 nm to 450 nm at room temperature. The PL spectra of the precipitated precipitates reveals emission in a wide UV-visible spectral range. It can be seen that the luminescence spectra have quite complex components and can be divided into five Gaussian curves. As can be seen the FL spectrum of the deposited ZnS consists of bands at 3.15 eV, 3.3 eV, 3.4 eV, 3.55 eV and 3.73 eV. Also analyzing the spectra energy dispersive analysis showed that the ZnS nanoproofs consist of Zn – 42.5% and S – 57.5%.

Zirconia Cementation: A Systematic Review of the Most Currently Used Protocols

Objective A systematic review of the existing literature was conducted and in vitro studies from 2019 to 2023 were analyzed on Zirconia's most resistant cementation protocol. Methods A systematic review of studies on the bond strength between zirconia and resin cement was carried out using different surface treatment protocols. The search was performed in two electronic databases, PubMed and Cochrane. Results Electronic searches yielded 1225 non-duplicated articles (Fig. 1), of which 388 were chosen after screening the titles and abstracts. After examining the full texts of these articles, a further 340 were excluded. There remained 48 studies to which the selection by inclusion and exclusion criteria was applied, eliminating 31 articles, of which 17 were finally included for the qualitative study. Conclusion Under the limitations of the present systematic review, it can be concluded that treating Zirconia with a combination of surface modifying agents, both mechanical and chemical, substantially improves its adhesive ability with resin cement. Aluminum oxide sandblasting, hydrofluoric acid etching, tribochemical silica coating, laser, and etching with a combination of acids in the Zircos E system are micromechanical treatments that improve the bond strength between zirconia and resin cements. MDP silane agent is an effective chemical treatment to improve the bond strength between zirconia and resin cements. Coating exclusively with a silica layer does not improve the bond strength between zirconia and resin cement.

Robust Transparent Photothermal Omniphobic Coating for Efficient Anti/Deicing and Antifogging.

Icing and fogging on optical material surfaces bring various problems in daily life. Recently, some photothermal coatings have been reported to prevent the condensation or freeze of water droplets by increasing the surface temperature. However, it is a great challenge to apply them in practical conditions due to their opaqueness and poor mechanical wear-resistant property. In this work, we constructed a robust transparent photothermal omniphobic coating with a simple dip-coating technique. In the coating system, photothermal polypyrrole nanoparticles are introduced into inorganic silica networks, and then polydimethylsiloxane (PDMS) brushes were grafted on the inorganic silica layer to endow the surface with omniphobicity and stain resistance. The transparency and photothermal capacity of the coating can be regulated by the deposition times of the coating. In addition, the coating has an excellent anti/deicing property and reduces ice adhesion obviously due to the existence of "liquid-like" PDMS brushes. More importantly, the coating presents outstanding mechanical wear-resistant and self-lubricating properties that can endure several thousand friction cycles without performance loss. The mechanically robust photothermal omniphobic coating gives a feasible approach to anti-icing and antifogging of transparent substrates under sunlight irradiation.

Level set simulation of focused ion beam sputtering of a multilayer substrate.

The evolution of a multilayer sample surface during focused ion beam processing was simulated using the level set method and experimentally studied by milling a silicon dioxide layer covering a crystalline silicon substrate. The simulation took into account the redeposition of atoms simultaneously sputtered from both layers of the sample as well as the influence of backscattered ions on the milling process. Monte Carlo simulations were applied to produce tabulated data on the angular distributions of sputtered atoms and backscattered ions. Two sets of test structures including narrow trenches and rectangular boxes with different aspect ratios were experimentally prepared, and their cross sections were visualized in scanning transmission electron microscopy images. The superimposition of the calculated structure profiles onto the images showed a satisfactory agreement between simulation and experimental results. In the case of boxes that were prepared with an asymmetric cross section, the simulation can accurately predict the depth and shape of the structures, but there is some inaccuracy in reproducing the form of the left sidewall of the structure with a large amount of the redeposited material. To further validate the developed simulation approach and gain a better understanding of the sputtering process, the distribution of oxygen atoms in the redeposited layer derived from the numerical data was compared with the corresponding elemental map acquired by energy-dispersive X-ray microanalysis.

Sputtered niobium pentoxide layers for optical applications

The use of pulsed DC magnetron sputtered niobium pentoxide as a high index material in optical devices as Anti-Reflecting Coating (ARC) and optical filters has been investigated. When deposited on a silicon substrate with native oxide, the few nanometers of niobium pentoxide were optically distinct from the rest of the niobium pentoxide layer, effect not observed on thermally oxidized silicon substrates. The dispersion curve of this interfacial layer was determined and used to simulate the reflectometry curves. Next, an ARC consisting of a bilayer of niobium pentoxide and silica was fabricated and its optical response was simulated with this interfacial layer. Finally, a Bragg mirror consisting of seventeen layers of niobium pentoxide and silicon dioxide was realized, underlining that this interfacial layer does not affect the optical response when several layers were at stake.

Optimal design of multilayer optical thin film structure for smart energy saving applications using needle optimization approach

In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.

Facilitating macroscopic superlubricity through graphene oxide nanosheet additives in phosphoric acid

The field of superlubricity is garnering significant global interest amid the ongoing energy crisis. Various liquids can achieve superlubricity under ambient conditions; however, this limits their applications, such as in acidic environments. Consequently, enhancing anti-wear properties and reducing the coefficient of friction (COF) have become pressing challenges. Graphene-based materials are being extensively studied for tribological applications, attributed to their unique molecular structures and lubricating properties, often serving as lubricating additives to significantly reduce COF. In this study, graphene oxide (GO) nanosheets were utilized as lubricating additives in phosphoric acid (H3PO4; pH = 1.5) to explore lubrication enhancement in acidic environments. An ultralow COF of 0.001 was achieved, accompanied by reduced surface roughness and increased contact pressure (by 96.42 %), following the lubrication with GO-H3PO4. The reduction in COF post-lubrication with GO-H3PO4 is ascribed to three primary factors: the formation of a tribofilm via chemical reactions (comprising silica and phosphorus oxide layers), the hydrogen bond effect leading to a hydrated water layer with low shear strength, and the adsorption of GO nanosheets on the friction surface, facilitating friction transfer from Si3N4/Si3N4 to GO/GO.

Enhanced antibacterial activity of multi-walled carbon nanotubes loaded with hot-melt extruded Mulberry leaf silver nanoparticles

We suggest an antibacterial nanoplatform composed of multi-walled carbon nanotubes (MWCNTs) coated with mesoporous silica decorated with silver nanoparticles (AgNPs) via an N-[3-(trimethoxysilyl)propyl]ethylenediamine (TSD)-mediated method. In this system, the external mesoporous silica shell enhances the dispersion of MWCNTs to increase their contact area with bacterial cell walls. Meanwhile, the multiple mesoporous voids in the silica layer serve as a microreactor for on-site synthesis of small-sized and uniformly distributed AgNPs, thereby enhancing the antibacterial activity. Mulberry leaf (ML) extract was used to reduce Ag ions. In this process, hot melt extrusion (HME) was applied to increase the active ingredients of the ML extract. To prevent loss of ML components due to the heat and pressure applied during HME treatment, several excipients, including whey protein isolate, were mixed, and added. Compared with ML AgNPs and mesoporous silica-coated MWCNTs decorated with AgNPs (MWCNT-Ag), the MWCNT-Ag@ML (MWCNT-ML) exhibited stronger antibacterial against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and methicillin-resistant S. aureus (MRSA). Therefore, this nano platform is a potential antibacterial agent and therapeutic agent for drug-resistant infections.

Superconducting single-photon detector integrated in DBR with optical microconnector for MM or SM fiber

This paper presents the development of a superconducting nanowire single-photon detector (SNSPD) integrated into a distributed Bragg reflector (DBR) with a design center wavelength of 830 nm and a bandwidth of 200 nm. This SNSPD is made of a superconducting niobium nitride (NbN) thin film that is produced using plasma-enhanced atomic layer deposition. The DBR is made of 15 alternating layers of silicon nitride and silicon oxide that are produced through plasma-enhanced chemical vapor deposition. The reflection efficiency of the mirror is 90% at a wavelength of 830 nm. For sufficient optical coupling, an optical micro-connector optimized for multimode or single-mode optical fibers with a diameter of 128 μm was formed using two-photon polymerization techniques. The niobium nitride film was deposited onto the DBR surface in-situ in two separate reactors connected by a vacuum transfer. The in-situ technique of deposition of a superconducting niobium nitride film and a DBR has allowed achieving a system detection efficiency of 90% at a wavelength of 830 nm and a dark count rate of 10 s−1 at a temperature of 2.5 K. Additionally, the detector jitter was 50 ps.

Double layer silica antireflective films with high strength and rub resistance prepared by sol gel method

The single-layer silica antireflective film with base catalysis prepared by sol gel method is an important part of the high-power laser facility for inertial confinement fusion, while the weak adhesion between the single-layer silica film and the substrate during the preparation process makes it susceptible to be contacted erasure and unable to be used. Double-layer silica antireflective (DLAR) films of different thicknesses were obtained using the base catalysis sol–gel method, in which the upper layer was coated with a relatively dense thin layer, and the performances of the films were characterized. The results showed that the transmittances of the DLAR films with different thicknesses were ˃99.0%, and in which one of the maximum transmittance peaks reached to 99.83% @ 1000 nm. The surface roughness of the DLAR films was < 2.0 nm, and the surfaces of the films were flat. The contact angles between DLAR films and water reached 118° and maintained stable in high humidity environment. The laser induced damage thresholds for different thickness DLAR films (peak transmittances @ 400, 600, 800, 1000 nm) were comparable to device requirements by 1-on-1 testing method, and the DLAR films exhibited high strength and good friction resistance.Graphical abstract

Sandwiched structure for temperature compensated laterally excited bulk wave resonators based on lithium niobate film

Recently, lithium niobate thin film laterally excited bulk wave resonators (XBARs) have attracted much attention because of their advantage of high frequency and outstanding electromechanical coupling factor (K2) enabling wide filter bandwidths. These can satisfy the increasing 5G communication demand. However, their large temperature coefficient limits their development to some extent. To improve their temperature stability with little K2 reduction, this paper has proposed a sandwiched structure for temperature compensated XBARs (TC XBARs). This structure includes the top silicon dioxide (SiO2) layer and the bottom SiO2 layer. One layer can improve temperature stability, and the other layer can increase K2. The optimized XBARs have a temperature coefficient of frequency (TCF) of −90.77 ppm⁄°C. The common two-layer TC XBARs can achieve a TCF of −22 ppm⁄°C sacrificing K2 to 8%. However, the proposed sandwiched TC XBARs can achieve a K2 of 12.15 and a TCF of −28.94 ppm⁄°C simultaneously, with a large FoM. Meanwhile, spurious modes can be suppressed in the sandwiched structure. Thus, this sandwiched structure can provide a good solution for the high performance of XBARs.

Stepwise ordering under nano-scale confinement in thin silica films

The phase transition from an amorphous 2D structure to a crystalline 3D structure under confinement is a fascinating and challenging problem in materials science and condensed matter physics. This work reports the Field Emission Scanning Electron Microscopy (FESEM) and energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), X-ray reflectivity (XRR), Fourier Transform Infrared Spectroscopy (FTIR) studies on pristine silica thin films. Silica was deposited on pristine Al (001) substrate (Alfa-Aesar) from tetraethyl orthosilicate (TEOS) precursor and thin films were spin-coated at different spinning frequencies under ambient conditions. The samples are highly porous and in-plane porosity varies from 30% to 60% as analyzed from both the FESEM and XRR and with increasing spinning frequency pores become more ordered. XRR shows that the samples are composed of two layers, a thick layer of aluminum oxide (Al2O3) as buffer layer and a layer of SiO2 on the top of the film. XRR shows sharp ordering rather than any layering. The film thickness varies from 90[Formula: see text]Å to 200[Formula: see text]Å and it shows a linear decay in the thickness of silica layer. In between 1000 and 1500[Formula: see text]rpm, XRR shows a sharp drop in the thickness of silica layer where thickness of this layer falls below the unit-cell dimension indicating higher-ordered crystallization under strained condition. XRD shows that there are no crystalline peaks coming from silica at lower rpm except the peaks of Al coming from the substrate. At 1000, 1200 and 1500[Formula: see text]rpm there is peak corresponding to the quartz, highly crystalline phase of SiO2 and where the substrate is slightly modified Al2O3. Reflection from (101) plane is prominent in all the films and it gives indication of formation 3D crystalline phase. Whereas FTIR shows that the Si–O stretching modes exhibit sharper and more defined reflectance peak compared to the broad bands observed in the samples in lower rpm. Observations suggest a clear indication of progressive ordering under confinement. To one extent, the results of XRR and FESEM will suggest the mechanism of transition from 2D amorphous to 3D crystalline phase under geometrical confinement effect and total confinement effect arising from thinning of the films with the increasing rpm, interfacial effect and on the other hand XRD and FTIR results will explain high ordering under confinement without any layering.