Thermal Nitridation Process Research Articles

Influence of initial crystalline phase of TiO2 to obtain TiN thin films from sol-gel route by rapid thermal nitridation process

Titanium Nitride (TiN) is widely used in many industrial sectors for its outstanding performances including its mechanical properties, high chemical and thermal stability. Associated with its plasmonic behavior, TiN thin films are very promising for the manufacturing of optical metasurfaces devices or new plasmonic materials. Among the processes that make it easy to obtain metal nitride coatings, nitriding of metal oxide films has become increasingly popular in recent years. A multitude of synthesis processes can be used to obtain TiO2 films, with different crystalline states (amorphous, anatase or rutile) depending on the technique used, which can then be converted into TiN coatings. In this paper, the effect of the initial crystalline state of TiO2 layers was investigated on the structural properties, plasmonic properties and the friction behavior of TiN thin films obtained by Rapid Thermal Nitridation (RTN). The results indicate that, regardless of the crystalline state of the starting TiO2 film, the RTN process leads to complete nitridation of TiN coating. Moreover, even though surface morphology and friction properties differ slightly, depending on the crystallization of the starting TiO2, plasmonic properties remain very similar, thus highlighting the great versatility and uniformity of this nitriding technique, enabling TiN to be produced for a wide range of applications.

Innovative process to obtain thin films and micro-nanostructured ZrN films from a photo-structurable ZrO2 sol-gel using rapid thermal nitridation

Zirconium nitride (ZrN) is widely used in many industrial sectors for its outstanding performances including its mechanical properties, high chemical and thermal stability. Associated with its plasmonic behavior, these properties make ZrN a suitable candidate for optical applications at high temperature or in extreme environments. The authors present an innovative, easy-to-use and rapid process for producing ZrN thin films from a photo-structurable ZrO2 sol-gel using a rapid thermal nitridation (RTN) process. In this process, a ZrO2 sol-gel layer is converted into a ZrN thin film in a few minutes by rapid thermal annealing (RTA) under ammonia gas. Compared to physical or chemical vapor deposition, usually used to produce ZrN thin films, the advantages of the sol-gel method include suitability for non-planar and large substrates and the possibility of nanotexturing of crystallized ZrN surfaces in considerably less time, at a larger scale and at a lower cost. The ZrO2 and ZrN thin films were characterized by Raman spectroscopy, X-ray diffraction and Transmission Electron Microscopy, to confirm complete nitridation. The optical, electrical and tribological properties were also investigated. Finally, the nitridation method was also used on structured ZrO2 layers and showed the versatility of the process e.g. enabling the production of micro-nanostructured ZrN films without using any etching techniques.

Tunning the single-phase triggered 3D mesostructured nitride with engineering the thermal nitridation effect for zinc-air batteries

Metallic surface constituents and partial oxidation are two factors that significantly influence not only the structure and morphology but also the performance and durability of an electrocatalyst. Herein, we report a structural design and optimization of a three-dimensional mesoporous electrocatalyst Ni3FeN through nanocasting followed by a thermal-nitridation process. Using annealing in NH3 ambiance at various controlled temperatures, different samples are synthesized. The sample Ni3FeN-420 (along with a secondary phase - metallic alloy Ni3Fe) annealed at 420 °C shows good catalytic activity reflected in very low overpotential (249 mV) towards oxygen evolution reaction (OER). The reached overpotential (η10) is lower than that observed in other ammoniated ternary nitrides (prepared using 370, 400, and 450 °C annealing temperatures), and metallic alloy Ni3Fe electrocatalysts. Also with due benchmarking, the superiority of Ni3FeN-420 is demonstrated. The material also has excellent durability showing no significant activity loss after 2000 cycles along with long‐term stability with an irrelevant drop of activity noted after 10 h toward OER in an alkaline electrolyte. Furthermore, the mixture of Ni3FeN-420 with Pt/C loaded on the positive electrode reveals greater and more stable performance for Zn–air battery (ZAB) than the benchmark catalysts (IrO2–Pt/C). This work opens an expressway for further investigation of the effect of material composition and synthesis conditions on electrocatalysis applications.

Study on exothermic effect of surface modified porous aluminum

Aluminum powder is widely used in the field of energy materials due to its high energy density. However, the combustion of aluminum powder is limited by the dense oxide film on the surface. In this study, surface modified porous aluminum (TFA@Al) was prepared by a simple chemical method. The morphology and structure of the TFA@Al surface were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The thermal oxidation and thermal nitridation processes of TFA@Al were analyzed by thermal analyzer (TG-DSC). The results show that the etched holes on the surface of TFA@Al can effectively promote the oxidation of aluminum and improve the exothermic effect of aluminum. The coupling reaction mechanism between Al core and oxygen at the etched holes is proposed. The explosion heat and combustion of thermite composed of TFA@Al and CuO (TFA@Al/CuO) and thermite composed of Al and CuO (Al/CuO) were also studied. The results show that TFA@Al/CuO has higher explosion heat value and emission spectral intensity than Al/CuO. Surface modified porous aluminum is expected to be used in the field of aluminum-containing energy materials.

Parasitic masking effect in GaN SA-MOVPE using SiO2 masks deposited by the PECVD technique

The paper reports a phenomenon of parasitic substrate masking during selective area metalorganic vapor phase epitaxy (SA-MOVPE) of gallium nitride (GaN) using silicon dioxide (SiO2) masks deposited by plasma enhanced chemical vapor deposition (PECVD) at pressures above 150 hPa. The discussion of the thermal stability and nitridation process of the SiO2 films is followed by the presentation of the experimental work results focused on the investigation of the relationship between the parasitic masking effect and pressure in the MOVPE reactor chamber. Analysis of the surface morphology is conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM). A hypothesis was proposed explaining the formation of the deposition-free region that indicates silanimine (HNSi) layer formation as a possible factor responsible for the adverse inhibition of GaN nucleation.

Manifestation of the Enhanced Photovoltaic Performance in Eco-Friendly AgBiS2 Solar Cells Using Titanium Oxynitride as the Electron Transport Layer

In this study, titanium oxynitride with empirical composition of TiON is developed using a sol–gel and ammonia-gas-assisted thermal nitridation process. The obtained TiON phase is employed as the photoanodic electron transport layer (ETL) in a silver bismuth sulfide (AgBiS2) quantum-dot-sensitized solar cell (QDSSC) device and compared to a QDSSC consisting of commercial TiO2 as the ETL. The obtained X-ray photoelectron spectroscopy spectra and Mott–Schottky plots of the samples suggested that the valence and conduction bands of TiON are significantly shifted (EVB = 2.9 eV and ECB = −0.3 eV) with respect to that of TiO2 (EVB = 1.88 eV and ECB = −0.51 eV), which eventually decreased its band gap energy to 2.46 eV compared to TiO2 (3.2 eV). A decrease in the charge transfer resistance (Rct = 38.2 Ω) and improvement in carrier lifetime (τ = 5.3 ms) are observed in the developed TiON device. The work also endorses the use of eco-friendly green quantum dots of AgBiS2 as photoabsorbers in solar cells. Although the photovoltaic performance is not found to be greater, the demonstration of the enhanced performance of the TiON-based device with ∼50% enhancements, owing to its improved open circuit voltage and current density by 20 and 35%, is achieved in this work. Titanium oxynitride can, hence, be considered a suitable alternative to existing commercial TiO2 in all applications that involve solar energy conversion.

N-polar GaN evolution on nominally on-axis c-plane sapphire by MOCVD Part-II: Microstructural investigation

The present work is part-II of a study that addresses in detail the microstructural features of nitrogen-polar gallium nitride (N-polar GaN) deposited on c-plane sapphire wafers under the metalorganic chemical vapor deposition conditions described in the part-I work. The growth process was interrupted at various stages and characterized the depositions using transmission electron microscopy. The plan view diffraction study in combination with the Moiré fringe analysis revealed the presence of rotational domains of 4° in the low-temperature GaN nucleation layer. A crystallographic basis for the occurrence of these rotational domains is proposed based on the arrangement of surface atoms in the underlying sapphire substrate. Pure a dislocations are found to accommodate the twist between the rotational domains. In addition, Ga-polar inversion domains are observed in the matrix of N-polar GaN, and they originate at atomic level steps induced by the initial thermal cleaning and nitridation process of sapphire wafers at 1100°C. The rotational domains, the accommodating a dislocations and the inversion domains are replicated into the N-polar GaN epilayers.

Versatile Micro and Nano Patterning Technique for TiO2 and TiN‐Based Sol–Gel Thin Films

AbstractThis paper describes a tailored and versatile technology route to achieve micro and nanopatterning of both TiO2 and TiN thin films using a direct photo patternable sol–gel approach combined with a rapid thermal annealing and nitridation process. The approach consists in multi‐scale structuring TiO2 using laser direct writing or mask/colloidal lithography on a wide range of substrates including materials and of diverse geometry. These patterned TiO2 layers can subsequently be converted into a micro‐structured metallic TiN layer using a direct rapid thermal nitridation process that results in metallic thin films (TiN). This work demonstrates the versatility of this complete chain of soft chemistry based new process for patterning TiO2 and TiN thin films thereby avoiding expensive processes such as etching and lift‐off, while preserving their diffractive properties and high thermal stability, that is, up to 1000 °C under vacuum. The process is compatible with different kinds of substrates of different shapes and sizes. These results pave the way for developing a cost‐effective and time‐saving approach to different cutting‐edge applications such as metasurfaces, sensors, and applications in the luxury and decoration sector.

Morphological effect on electrochemical performance of nanostructural CrN* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11904299, U1930124, and 11804312) and China Academy of Engineering Physics (CAEP) Foundation (Grant No. 2018AB02).

Size and morphology are critical factors in determining the electrochemical performance of the supercapacitor materials, due to the manifestation of the nanosize effect. Herein, different nanostructures of the CrN material are prepared by the combination of a thermal-nitridation process and a template technique. High-temperature nitridation could not only transform the hexagonal Cr2O3 into cubic CrN, but also keep the template morphology barely unchanged. The obtained CrN nanostructures, including (i) hierarchical microspheres assembled by nanoparticles, (ii) microlayers, and (iii) nanoparticles, are studied for the electrochemical supercapacitor. The CrN microspheres show the best specific capacitance (213.2 F/g), cyclic stability (capacitance retention rate of 96% after 5000 cycles in 1-mol/L KOH solution), high energy density (28.9 Wh/kg), and power density (443.4 W/kg), comparing with the other two nanostructures. Based on the impedance spectroscopy and nitrogen adsorption analysis, it is revealed that the enhancement arised mainly from a high-conductance and specific surface area of CrN microspheres. This work presents a general strategy of fabricating controllable CrN nanostructures to achieve the enhanced supercapacitor performance.

Resistive Switching Behavior of Titanium Oxynitride Fabricated Using a Thermal Nitridation Process

A titanium oxynitride (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> ) resistive random-access memory (RRAM) with write-once-read-many-times (WORM) characteristics is proposed. The TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> resistive switching (RS) layer with a thickness of 62 nm was fabricated using a thermal nitridation process of an evaporated Ti metal film. The residual Ti layer with a thickness of 8 nm is used as the bottom contact. The Al/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> /Ti/n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -Si RRAM shows a large memory window of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> at a low read voltage of 0.2 V. Stable high-resistance state (HRS) and low-resistance state (LRS) are observed in the endurance test for 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> read cycles. High read-disturb immunity can be found for over 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> s. The energy band diagram, carrier conduction and the RS mechanisms of the RRAM are investigated.

Optical, electrical and mechanical properties of TiN thin film obtained from a TiO2 sol-gel coating and rapid thermal nitridation

This study reports the optical, electrical and mechanical properties of TiN films prepared by direct rapid thermal nitridation process from a photo-patternable TiO2 sol-gel layer. The sol-gel approach is compatible to non-planar and large substrates and allows the micro-nanotexturing of crystallized TiN surfaces in a significantly short time, large scale and at a lower cost compared to TiN layer deposition from existing and conventional processes (CVD, PVD, ALD…). In this paper, the optical measurements are carried out by optical spectroscopy in the UV, visible and near-IR region and by ellipsometry. The resistivity and the conductivity are estimated by four-point probe method, while hardness is characterized by nano-indentation experiments. The results indicate that the TiN thin film made by sol-gel method and rapid thermal nitridation are very promising for the manufacturing of optical metasurfaces devices or new plasmonic materials.

Simultaneous enhancement of impedance matching and the absorption behavior of BN/RGO nanocomposites for efficiency microwave absorption

In this work, to meet the comprehensive demands for efficiency and lightweight electromagnetic wave absorption (EWA) material, boron nitride/reduced graphene oxide (BN/RGO) nanocomposites were prepared via a one-step thermal nitridation process. The insulative BN component in the obtained nano BN/RGO hybrids realized the regulation of conductivity and thus impedance matching, and the large interface area of the hybrids facilitated the high-frequency polarization effect and contributed to the enhanced EWA performance. Remarkably, the EWA performance of optimized BN/RGO hybrids reached a strong reflection loss (RL) of −48.9 dB in a broad effective absorption bandwidth of 4.2 GHz with a low filler content of 3.0 wt. % and at a thin thickness of 2.6 mm, which well outperforms that of most other reported dielectric absorption materials. Our results may light a new way on introducing light element component to produce high-efficiency RGO-based EWA materials with facile and low-cost production process.

Rapid Synthesis of Aluminum Nitride Nanopowders from Gaseous Aluminum Chloride

The synthesis of aluminum nitride (AlN) powders is traditionally completed through a thermal nitridation process, in which the reacting aluminum powders are combined with nitrogen at high temperatures with a long reaction time (usually several hours). Moreover, the occurrence of agglomeration within the melting Al particles results in a poor dispersibility of AlN powders, with a low efficiency of nitridation. In this study, an atmosphere-pressure microwave plasma preceded the rapid gas-gas synthesis process. In the reactor, the gaseous aluminum chloride (AlCl3) reactant was fed at different positions (R1, R2, R3) to react with nitrogen at various reaction temperatures (690~1150°C) to rapidly produce AlN nano powders (in several seconds). The process was operated at a total flow rate of 13 slm with NH3 gas content of 0 or 0.77% and an applied power of 1200/1400 W. Results showed that the high purity and dispersibility of AlN powders were found at a AlCl3 feeding position closer to the resonant cavity of the reactor (R3, 1150°C). The AlN particle size was in the range of 25-50 nm. The experiments indicated that the gas-gas reaction for rapidly synthesizing AlN nanopowders can be successfully carried out via an AlCl3-N2 plasma-chemical approach.

TiN/Ni/C ternary composites with expanded heterogeneous interfaces for efficient microwave absorption

At present, constructing composite materials with different absorbing mechanism is the popular strategy to realize the complementary and synergetic properties for electromagnetic (EM) wave absorbing materials. However, the effective magnetic response is generally struggled to achieve. Besides the composition design strategy, fully utilizing the interfacial polarization is another efficient method for the fabrication of microwave absorbing (MA) materials. In this work, the titanium nitride/nickel/carbon (TiN/Ni/C) ternary composites were fabricated through an in-situ thermal nitridation process. The EM dissipation factors can be regulated by rational design of the ternary heterogeneous interface through varying the precursor composition. The minimum reflection loss (RL) of the optimized TiN/Ni/C nanocomposite can reach −35.1 dB at 12.4 GHz and the effective absorption bandwidth (EAB) is 3.6 GHz with a thickness of 1.7 mm. The enhanced absorbing property is benefited from the effective structure design with tunable heterogeneous interface and continuous carbon matrix which would achieve promoted interfacial polarization, conductivity relaxation and the electromagnetic impedance matching. Special structures of TiN/Ni/C ternary composites played a vital role in the effective electromagnetic absorption properties, which is significant for designing efficient MA materials.

High performance and lightweight electromagnetic wave absorbers based on TiN/RGO flakes

In this study, titanium nitride (TiN)/reduced graphene oxide (RGO) composites were prepared via a facile hydrothermal and thermal nitridation process. Due to their favorable electromagnetic wave dissipation ability and appropriate electromagnetic (EM) impedance matching, the TiN/RGO flakes embodies distinct advantage as compared to single component RGO nanosheets and TiN nanoparticles. Moreover, the effective electromagnetic absorption frequency range of the TiN/RGO flakes could be designed by controlling the mass ratio of the precursor. When the mass ratio of nanosized titanic acid to graphene oxide is 1.4:1, the reflection loss of the TiN/RGO with only 2.0 wt% absorber loading reaches −42.85 dB at 8.88 GHz with a thickness of 4.0 mm and a broad effective absorption bandwidth (RL < −10 dB) of 6.7 GHz, which compete well with those observed in several RGO-based composites with much higher filler loadings. The combined excellent EM absorption property with simple production procedure and ultralow absorbent content requirement endow the TiN/RGO flakes as a promising lightweight and efficient EM absorption material suitable for harsh application conditions.

Two-Stage Plasma-Thermal Nitridation Processes for the Production of Aluminum Nitride Powders from Aluminum Powders.

The synthesis of aluminum nitride (AlN) powders is traditionally done via the thermal nitridation process, in which the reaction temperature reaches as high as 960 °C, with more than several hours of reaction time. Moreover, the occurrence of agglomeration in melting Al particles results in poor AlN quality and a low efficiency of nitridation. In this study, an atmosphere-pressure microwave-plasma preceded the pre-synthesis process. This process operates at 550 °C for 2–10 min with the addition of NH4Cl (Al: NH4Cl = 1:1) for generating a hard AlN shell to avoid the flow and aggregation of the melting Al metals. Then, the mass production of AlN powders by the thermal nitridation process can be carried out by rapidly elevating the reaction temperature (heating rate of 15 °C/min) until 1050 °C is reached. X-Ray Diffractometer (XRD) crystal analysis shows that without the peak, Al metals can be observed by synthesizing AlN via plasma nitridation (at 550 °C for 2 min, Al: NH4Cl = 1:1), followed by thermal nitridation (at 950 °C for 1 h). Moreover, SEM images show that well-dispersed AlN powders without agglomeration were produced. Additionally, the particle size of the produced AlN powder (usually < 1 μm) tends to be reduced from 2–5 μm (Al powders), resulting in a more efficient synthesizing process (lower reaction temperature, shorter reaction time) for mass production.

Fabrication of TiN/Carbon nanofibers by electrospinning and their electromagnetic wave absorption properties

In this work, titanium nitride/carbon (TiN/C) nanofibers were prepared via a combination of electrospinning process and thermal nitridation process. For the first time, their microwave absorption performance was investigated based on the polarization loss and impedance matching characteristic. The result showed that a thin sample consisting of 15 wt% hybrid nanofibers in the wax matrix exhibited excellent microwave absorption property (RL<-20 dB, 99% EM wave absorbed) in a broad frequency range (8.0–15.0 GHz) at the thickness less than 2.5 mm. Both the optimal reflection loss and the effective absorption bandwidth competes well with what has been observed in the composites with much higher filler loadings. The prepared TiN/C nanofibers could be used as lightweight and high-performance microwave absorbing materials.

Two-stage plasma nitridation approach for rapidly synthesizing aluminum nitride powders

Abstract

Synthesis and electrochemical performance of Li4Ti5O12 submicrospheres coated with TiN as anode materials for lithium-ion battery

The TiN coated Li4Ti5O12 (LTO) submicrospheres with high electrochemical performance as anode materials for lithium-ion battery were synthesized successfully by solvothermal method and subsequent nitridation process in the presence of ammonia. The XRD results revealed that the crystal structure of LTO did not change after thermal nitridation process. The submicrospheres morphology of LTO and TiN film on the surface of LTO submicrospheres were characterized by FESEM and HRTEM, respectively. XPS result confirmed that a small amount of Ti changed from Ti4+ to Ti3+ after nitridation process, which will increase the electronic conductivity of LTO. Electrochemical results showed that electrochemical performance of TiN coated LTO anode materials compared favorably with that of pure LTO. Also its rate capability and cycling performance were apparently superior to those of pure LTO. The reversible capacity of TiN-LTO is 105.2mAhg−1 at a current density of 10 C after 100 cycles and maintain 92.9% of its initial discharge capacity, while that of pure LTO is only 83.6mAhg−1 with a capacity retention of 90.3%. Even at 20 C, the discharge capacity of TiN coated LTO sample is 101.3mAhg−1, compared with 77.3mAhg−1 for pristine LTO in the potential range 1.0–2.5V (vs. Li/Li+).

A Study on Chamber Contamination Control of Rapid Thermal Nitridation Process By Applying Quartz Liner

To improve the characteristics of barrier wall in DRAM plug contact via, the rapid thermal nitridation(RTN) process has been widely used via rapid thermal process chamber. With combination of high temperature heat, process gas such as NH3 and wafer being processed, the Ammonium Chloride(NH4Cl) is generated as a byproduct of this process and chamber is contaminated by NH4Cl depositing on the reflector. This contaminant diffracts the thermal energy which comes into pyrometers and degrades process quality. To prevent this chamber contamination from the byproduct such as NH4Cl, the transparent quartz liner on reflector plate is adopted. In this study, the influence of quartz liner on reflector plate, the improvement of chamber contamination and pyrometer sensitivity were investigated. In RTN process, TiSix or CoSix is formed in Si contract area as an ohmic contact and improves the adhesion with tungsten by transducing Ti to TiN.[1] Eq.1 shows how Ammonium Chloride (NH4Cl(s)) is generated during RTN process as a byproduct. NH4Cl sublimes at 337.6°C and the reflector plate increases no more than 225.3°C at 1000°C, 90sec process condition. Therefore NH4Cl is deposited on the chamber wall as well as reflector plate. Fig.1 shows the diagram of NH4Cl deposition on reflector plate as a contaminant. This contaminant diffracts the thermal energy which comes into pyrometers and degrades the silicide uniformity. In Fig.2, device “A” at target temperature has more uniform shape than device “B” which has been processed in lower temperature than target of “A”. Fig.3 shows transparent quartz in RTP chamber to prevent reflector plate from the contaminant. Fig.4 shows presence of quartz liner has very stable halogen lamps power dissipation than without quartz. Fig.5 shows temperature error against target value with quartz liner is much lower than without quartz. In this paper, the influence of quartz liner on reflector plate, the improvement of chamber contamination and pyrometer sensitivity were investigated. From experimental result, presence of quartz liner protects reflector plate from contamination and keeps power dissipation of halogen lamps in stable. As a result, it means that more accurate heat control is possible in RTN process which could affect the quality of plug contacts of semiconductor device. Reference [1] ] Zhao Wenbin, Chen Haifeng, XiaoZhiqiang, Li leilei, Yu Zongguang, Journal of Semiconductors (2009) 056001 Figure 1