Search Results (38)

Silicon oxynitride (SiO_xN_y, hereafter denoted as SiON) thin films represent an intermediate phase between silicon dioxide (SiO₂) and silicon nitride (Si₃N₄). Through systematic compositional ratio adjustments, the refractive index can be precisely tuned across a wide range from 1.45 to 2.3. However, the underlying mechanism governing the influence of elemental composition on film structural quality remains insufficiently understood. To address this knowledge gap, we systematically investigate the effects of key industrial plasma-enhanced chemical vapor deposition (PECVD) parameters—including precursor gas selection and flow rate ratios—on SiON film properties. Our experimental measurements reveal that stoichiometric SiO_xN_y (x = y) achieves a minimum surface roughness of 0.18 nm. As oxygen content decreases and nitrogen content increases, progressive replacement of Si-O bonds by Si-N bonds correlates with increased structural defect density within the film matrix. Capacitance–voltage (C-V) characterization demonstrates a corresponding enhancement in device capacitance following these compositional modifications. Recent studies confirm that controlled modulation of film stoichiometry enables precise tailoring of dielectric properties and capacitive behavior, as demonstrated in SiON-based power electronics, thereby advancing applications in related fields. Full article

Silicon nitride (SiN) films deposited via plasma-enhanced chemical vapor deposition (PECVD) exhibit tunable tensile stress, which is critical for various microelectronic and optoelectronic applications. In this paper, the effects of silane (SiH₄) flow rate during PECVD deposition, ultraviolet (UV) curing, and layered deposition on the tensile stress of SiN films are mainly investigated. The results reveal that increasing the SiH₄ concentration raises hydrogen incorporation, which modifies internal stress dynamics. UV curing significantly increases tensile stress by breaking N-H and Si-H bonds, facilitating hydrogen desorption, and promoting Si-N-Si crosslinking. The optimal UV curing duration stabilizes tensile stress at approximately 1570 MPa, while excessive UV power alters hydrogen content dynamics, reducing stress. Additionally, layered deposition further amplifies stress enhancement, with films subjected to multiple deposition cycles exhibiting increased densification and crosslinking. The combined optimization of PECVD deposition parameters, UV curing, and layered deposition provides a robust strategy for tailoring SiN film stress, offering a versatile approach to engineering mechanical properties for advanced applications. Full article

An uncooled microbolometer is a thermal sensor consisting of a membrane suspended from the substrate to provide thermal insulation. Typically, the membrane is composed of a stack of three films integrated by a supporting film, an IR sensing film, and an IR absorbing film. However, the above increases the thickness of the device and affects its mechanical stability and thermal mass, thereby reducing its performance. One solution is to use a single film as a membrane with both IR sensing and IR absorbing properties. In this regard, this work presents the fabrication and evaluation of uncooled microbolometers using nitrogen-doped hydrogenated amorphous silicon-germanium (a-SiGe:H,N) as a single IR-absorber/IR sensing membrane. The films were deposited via low frequency Plasma Enhanced Chemical Vapor Deposition (PECVD) at 200 °C. Three microbolometer configurations were fabricated using a-SiGe:H,N films deposited from a SiH₄, GeH₄, N_2, and H₂ gas mixture with different SiH₄ and GeH₄ flow rates and, consequently, with different properties, such as temperature coefficient of resistance (TCR) and conductivity at room temperature. The microbolometer that exhibited the best performance achieved a voltage responsivity of 7.26 × 10⁵ V/W and a NETD of 22.35 mK at 140 Hz, which is comparable to state-of-the-art uncooled infrared (IR) sensors. These results confirm that the optimization of the deposition parameters of the a-SiGe:H,N films significantly affects the microbolometers final performance, enabling an optimal balance between thermal sensitivity (TCR) and conductivity. Full article

This study investigates the mechanical and optical characteristics of silicon nitride thin films deposited with PECVD at 80 °C for tunable silicon-rich SiN_x-SiO_y-based MEMS optical cavities. Varying the deposition parameters using SiH₄ and N₂ as precursor gases for silicon-rich SiN_x thin films allows us to tune the refractive index to a value as high as 2.40 ± 0.013 at an extinction coefficient of only 0.008, an extremely low surface roughness of only 0.26 nm, and a compressive stress of about 150 MPa. We deposited 6.5-layer pairs of silicon-rich SiN_x/SiO_y-distributed Bragg reflector (DBR) micro-electro-mechanical system (MEMS) mirror that covers the whole 1300 and 1550 nm range. Cavity architectures of 6.5 top and 6 bottom layer-pairs were fabricated in the clean room providing a variety of cavity lengths between 0.615 µm and 2.85 µm. These lengths were then simulated in order to estimate the Young’s Modulus of silicon-rich SiN_x, obtaining values from 56 to 92 GPa. One of the designs was characterised electro-thermally providing a tuning range of at least 86.7 nm centred at 1585 nm. The tunable filters are well suitable for implementation as tuning element in lasers for optical coherence tomography. Full article

In this research, two intermediate layers were deposited on 316L stainless steel to improve the adhesion of diamond-like carbon (DLC) films, one composed of Ti_xAl and produced using the RF sputtering technique with three thicknesses, 100 nm, 200 nm, and 300 nm; the other, interlayer composed of amorphous hydrogenated silicon (a-Si:H). The DLC films were deposited using the pulsed-DC PECVD method with an active screen to achieve the AISI 316L/Ti_xAl//DLC and AISI 316L/TiₓAl/a-Si/DLC configurations. The binding energy between the substrate/Ti_xAl and Ti_xAl/a-Si:H was investigated via X-ray photoelectron spectroscopy with high-resolution spectra. The chemical composition and microstructure of the titanium–aluminum interlayers were investigated using energy-dispersive X-ray spectroscopy and X-ray diffraction, and the microstructure of the DLC coatings was studied using Raman spectroscopy. The coatings’ adherence was measured using scratch and indentation tests, and the hardness of the DLC coatings was determined with the nanoindentation test. The X-ray diffractograms did not allow the determination of any crystalline structure in the Ti_xAl interlayers. The XPS results showed that between the AISI 316L substrate and the Ti_xAl intermediate layer, Ti-O-Fe and FeAl₂O₄ were formed. On the other hand, at the Ti_xAl/a-Si:H interface, TiSi₂ and Al₂SiO₅ compounds were identified. The DLC coatings grew as hydrogenated amorphous carbon with a hydrogen content of around 30 at.% and a hardness of 24 GPa. The deposition methods used and the Ti_xAl/a-Si:H interlayers allowed the obtainment of adherent DLC coatings on AISI 316L stainless steel substrates. High critical load values of about 30 N were obtained. The novelty of this work is underscored by the absence of previous studies that thoroughly examine the bonds present in interlayers used as gradients to enhance the adhesion of DLC. Full article

In order to solve the problem of the corrosion and wear of N80 metal pipelines exposed to corrosive media and abrasive sand during the development of petroleum resources, the proposed solution involves utilizing HC-PECVD technology to deposit a series of multilayer Si-DLC films with varying thicknesses on the inner surfaces of the N80 steel pipes. This investigation systematically explored the microstructure, mechanical properties, tribological features, and corrosion resistance of the multilayer Si-DLC films. Remarkably, after coating the multilayer (Si-DLC)₄₀ film on the inner wall of the N80 tube, the friction coefficient decreased from 0.7~0.75 to 0.2~3, and the wear rate decreased by two orders of magnitude. In addition, the corrosion current decreased by 50%, and the impedance doubled in a 3.5 wt% NaCl solution saturated with CO₂. Thus, the multilayer (Si-DLC)₄₀ film on the inner wall of the N80 tube exhibited superior tribological properties and exceptional corrosion resistance. These findings are anticipated to furnish valuable data and technical insights for mitigating corrosion in N80 steel pipes during petroleum exploitation. Full article

Nanocrystalline silicon oxide (nc-SiOx:H) is a multipurpose material with varied applications in solar cells as a transparent front contact, intermediate reflector, back reflector layer, and even tunnel layer for passivating contacts, owing to the easy tailoring of its optical properties. In this work, we systematically investigate the influence of the gas mixture (SiH₄, CO₂, PH₃, and H₂), RF power, and process pressure on the optical, structural, and passivation properties of thin n-type nc-SiOx:H films prepared in an industrial, high-throughput, plasma-enhanced chemical vapor deposition (PECVD) reactor. We provide a detailed description of the n-type nc-SiOx:H material development using various structural and optical characterization techniques (scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Raman spectroscopy, and spectroscopic ellipsometry) with a focus on the relationship between the material properties and the passivation they provide to n-type c-Si wafers characterized by their effective carrier lifetime (τ_eff). Furthermore, we also outline the parameters to be kept in mind while developing different n-type nc-SiOx:H layers for different solar cell applications. We report a tunable optical gap (1.8–2.3 eV) for our n-type nc-SiOx:H films as well as excellent passivation properties with a τ_eff of up to 4.1 ms (implied open-circuit voltage (iV_oc)~715 mV) before annealing. Oxygen content plays an important role in determining the crystallinity and hence passivation quality of the deposited nanocrystalline silicon oxide films. Full article

The application of surface coatings is a popular technique to improve the performance of materials used for medical and dental implants. Ternary silicon carbon nitride (SiCN), obtained by introducing nitrogen into SiC, has attracted significant interest due to its potential advantages. This study investigated the properties of SiCN films deposited via PECVD for dental implant coatings. Chemical composition, optical, and tribological properties were analyzed by adjusting the gas flow rates of NH₃, CH₄, and SiH₄. The results indicated that an increase in the NH₃ flow rate led to higher deposition rates, scaling from 5.7 nm/min at an NH₃ flow rate of 2 sccm to 7 nm/min at an NH₃ flow rate of 8 sccm. Concurrently, the formation of N-Si bonds was observed. The films with a higher nitrogen content exhibited lower refractive indices, diminishing from 2.5 to 2.3 as the NH₃ flow rate increased from 2 sccm to 8 sccm. The contact angle of SiCN films had minimal differences, while the corrosion rate was dependent on the pH of the environment. These findings contribute to a better understanding of the properties and potential applications of SiCN films for use in dental implants. Full article

This study reports the chemical vapor deposition of amorphous boron carbonitride films on Si(100) and SiO₂ substrates using a trimethylamine borane and nitrogen mixture. BC_xN_y films with different compositions were produced via variations in substrate temperature and type of gas-phase activation. The low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD) methods were used. The “elemental composition—chemical bonding state—properties” relationship of synthesized BC_xN_y was systematically studied. The hydrophilicity, mechanical, and optical properties of the films are discussed in detail. The composition of films deposited by the LPCVD method at temperatures ranging from 673 to 973 K was close to that of boron carbide with a low nitrogen content (BC_xN_y). The refractive index of these films changed in the range from 2.43 to 2.56 and increased with temperature. The transparency of these films achieved 85%. LPCVD films were hydrophilic and the water contact angles varied between 53 and 63°; the surface free energy was 42–48 mN/m. The microhardness, Young’s modulus and elastic recovery of LPCVD films ranged within 24–28 GPa, 220–247 GPa, and 70–74%, respectively. The structure of the PECVD films was close to that of hexagonal boron nitride, and their composition can be described by the BC_xN_yO_z:H formula. In case of the PECVD process, the smooth films were only produced at low deposition temperatures (373–523 K). The refractive index of these films ranged from 1.51 to 1.67. The transparency of these films achieved 95%; the optical band gap was evaluated as 4.92–5.28 eV. Unlike LPCVD films, they were very soft, and their microhardness, Young’s modulus and elastic recovery were 0.8–1.4 GPa, 25–26 GPa, and 19–28%, respectively. A set of optimized process parameters to fabricate LPCVD BC_xN_y films with improved mechanical and PECVD films with high transparency is suggested. Full article

We utilized a plasma-enhanced atomic layer deposition (PEALD) process to deposit an AlN passivation layer on AlGaN/GaN surface to enhance the polarization effects, which enabled the fabrication of an enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor heterojunction field-effect transistor (MIS-HFET) without the need for a gate recess process. The AlN film deposited by PEALD exhibited a crystalline structure, not an amorphous one. The enhanced polarization effect of introducing the PEALD AlN film on a thin AlGaN barrier was confirmed through electrical analysis. To fabricate the E-mode AlGaN/GaN MIS-HFET, the PEALD AlN film was deposited on a 4.5 nm AlGaN barrier layer and then a damage-free wet etching process was used to open the gate region. The MIS-gate structure was formed by depositing a 15 nm plasma-enhanced chemical vapor deposition (PECVD) silicon dioxide (SiO₂) film. The fabricated thin-AlGaN/GaN MIS-HFET demonstrated successful E-mode operation, with a threshold voltage of 0.45 V, an on/off ratio of approximately 10⁹, a specific on-resistance of 7.1 mΩ·cm², and an off-state breakdown voltage exceeding 1100 V. Full article

The effect of a-SiC_xN_y:H encapsulation layers, which are prepared using the very-high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) technique with SiH₄, CH₄, and NH₃ as the precursors, on the stability and photoluminescence of CsPbBr₃ quantum dots (QDs) were investigated in this study. The results show that a-SiCxNy:H encapsulation layers containing a high N content of approximately 50% cause severe PL degradation of CsPbBr₃ QDs. However, by reducing the N content in the a-SiCxNy:H layer, the PL degradation of CsPbBr₃ QDs can be significantly minimized. As the N content decreases from around 50% to 26%, the dominant phase in the a-SiCxNy:H layer changes from SiNx to SiCxNy. This transition preserves the inherent PL characteristics of CsPbBr₃ QDs, while also providing them with long-term stability when exposed to air, high temperatures (205 °C), and UV illumination for over 600 days. This method provided an effective and practical approach to enhance the stability and PL characteristics of CsPbBr₃ QD thin films, thus holding potential for future developments in optoelectronic devices. Full article

PECVD SiC:H (SiCN:H) films were produced using tetramethylsilane (TMS) as a precursor in a mixture with inert helium or ammonia as a source of nitrogen. Mild plasma conditions were chosen in order to prevent the complete decomposition of the precursor molecules and promote the incorporation of the fragments of precursor into the film structure. The effect of deposition temperature and composition of gas mixture on the chemical bonding structure, elemental composition, deposition rate, and optical properties (transmittance, optical bandgap, and refractive index) of films have been examined. Use of the chosen deposition conditions allowed them to reach a relatively high deposition rate (up to 33 nm/min), compared with films produced in high plasma power conditions. Use of ammonia as an additional gas led to effective incorporation of N atoms in the films. The composition of the films moved from SiC:H to SiN:H with increasing of ammonia content to P(NH₃)/P(TMS) = 1. The refractive index and optical bandgap of the films varied in the range of 1.55–2.08 and 3.0–5.2 eV, correspondingly, depending on the film composition and chemical bonding structure. The effect of treatment of SiCN films deposited at 400 °C by plasma of He, O₂ or NH₃ were studied by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. It was shown that plasma treatment significantly changes the surface characteristics. The water contact angle of the film was changed from 71 to 37° after exposure in the plasma conditions. Full article

Single-walled carbon nanotubes (SWCNTs) have an advantage in printing thin film transistors (TFTs) due to their high carrier mobility, excellent chemical stability, mechanical flexibility, and compatibility with solution-based processing. Thus, the printed SWCNT-based TFTs (pSWCNT-TFTs) showed significant technological potential such as integrated circuits, conformable sensors, and display backplanes. However, the long-term environmental stability of the pSWCNT-TFTs hinders their commercialization. Thus, to extend the stability of the pSWCNT-TFTs, such devices should be passivated with low water and oxygen permeability. Herein, we introduced the silicon nitride (SiNx) passivation method on the pSWCNT-TFTs via a combination of roll-to-roll (R2R) gravure and the roll-to-roll plasma-enhanced vapor deposition (R2R-PECVD) process at low temperature (45 °C). We found that SiNx-passivated pSWCNT-TFTs showed ± 0.50 V of threshold voltage change at room temperature for 3 days and ±1.2 V of threshold voltage change for 3 h through a Temperature Humidity Test (85/85 test: Humidity 85%/Temperature 85 °C) for both p-type and n-type pSWCNT-TFTs. In addition, we found that the SiNx-passivated p-type and n-type pSWCNT-TFT-based CMOS-like ring oscillator, or 1-bit code generator, operated well after the 85/85 test for 24 h. Full article

In this study, a silicon carbon nitride (SiCN) thin film was grown with a thickness of 5~70 nm by the plasma-enhanced chemical vapor deposition (PECVD) method, and the oxygen permeation characteristics were analyzed according to the partial pressure ratio (PPR) of tetramethylsilane (4MS) to the total gas amount during the film deposition. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and X-ray reflectivity (XRR) were used to investigate the composition and bonding structures of the SiCN film. An atomic force microscope (AFM) was used to examine the surface morphology of the SiCN films to see the porosity. The analysis indicated that Si–N bonds were dominant in the SiCN films, and a higher carbon concentration made the film more porous. To evaluate the oxygen permeation, a highly accelerated temperature and humidity stress test (HAST) evaluation was performed. The films grown at a high 4MS PPR were more susceptible to oxygen penetration, which changed Si–N bonds to Si–N–O bonds during the HAST. These results indicate that increasing the 4MS PPR made the SiCN film more porous and containable for oxygen. As an application, for the first time, SiCN dielectric film is suggested to be applied to resistive random access memory (RRAM) as an oxygen reservoir to store oxygen and prevent a reaction between metal electrodes and oxygen. The endurance characteristics of RRAM are found to be enhanced by applying the SiCN. Full article

In this work, we explored the feasibility of the fabrication of PIN light-emitting diodes (LEDs) consisting of heterojunctions of amorphous silicon-carbide (a-Si_1−xC_x:H) thin films and crystalline silicon wafers (c-Si). The objective is the future development of electro-photonic systems in the same c-Si wafer, containing transistors, sensors, LEDs and waveguides. Two different heterojunction LEDs were fabricated consisting of PIN and PIN⁺N structures, where a-Si_1−xC_x:H thin films were used as P-type and I-type layers, while an N-type c-Si substrate was used as an active part of the device. The amorphous layers were deposited by the plasma-enhanced chemical vapor deposition (PECVD) technique at a substrate temperature of 200 °C. The PIN device presented electroluminescence (EL) only in the forward bias, while the PIN⁺N device presented in both the forward and reverse biases. The EL in reverse bias was possible due to the addition of an N⁺-type a-Si:H layer between the c-Si substrate and the I-type a-Si_1−xC_x:H active layer. Likewise, the EL intensity of the PIN⁺N structure was higher than that of the PIN device in forward bias, indicating that the addition of the N-type a-Si:H layer makes electrons flow more efficiently to the I layer. In addition, both devices presented red EL in the full area, which is observed with the naked eye. Full article