Search Results (72)

Owing to high electrical conductivity, layered structure, and abundant surface functional groups, transition metal carbides/nitrides (MXenes) have received enormous interest in the field of gas sensors at room temperature. In this work, we synthesize a heterostructured nanocomposite with indium oxide (In₂O₃) decorated on titanium carbide (Ti₃C₂T_x) nanosheets by electrostatic self-assembly and develop it for high-selectivity NO₂ gas sensing at room temperature. Self-assembly formation of multiple heterojunctions in the In₂O₃/Ti₃C₂T_x composite provide abundant NO₂ gas adsorption sites and high electron transfer activity, which is conducive to improving the gas-sensing response of the In₂O₃/Ti₃C₂T_x gas sensor. Assisted by rich adsorption sites and hetero interface, the as-fabricated In₂O₃/Ti₃C₂T_x gas sensor exhibits the highest response to NO₂ among various interference gases. Meanwhile, a detection limit of 0.3 ppm, and response/recovery time (197.62/93.84 s) is displayed at room temperature. Finally, a NO₂ sensing mechanism of In₂O₃/Ti₃C₂T_x gas sensor is constructed based on PN heterojunction enhancement and molecular adsorption. This work not only expands the gas-sensing application of MXenes, but also demonstrates an avenue for the rational design and construction of NO₂-sensing materials. Full article

Recent advancements in hybrid photonic integrated circuits (PICs) for wireless communications are reviewed, with a focus on innovations developed at Fraunhofer HHI. This work leverages hybrid integration technology, which combines indium phosphide (InP) active elements, silicon nitride (Si₃N₄) low-loss waveguides, and high-efficient thermal-optical tunable polymers with micro-optical functions to achieve fully integrated wireless transceivers. Key contributions include (1) On-chip optical injection locking for generating phase-locked optical beat notes at 45 GHz, enabled by cascaded InP phase modulators and hybrid InP/polymer tunable lasers with a 3.8 GHz locking range. (2) Waveguide-integrated THz emitters and receivers, featuring photoconductive antennas (PCAs) with a 22× improved photoresponse compared to top-illuminated designs, alongside scalable 1 × 4 PIN-PD and PCA arrays for enhanced power and directivity. (3) Beam steering at 300 GHz using a polymer-based optical phased array (OPA) integrated with an InP antenna array, achieving continuous steering across 20° and a 10.6 dB increase in output power. (4) Demonstration of fully integrated hybrid wireless transceiver PICs combining InP, Si₃N₄, and polymer material platforms, validated through key component characterization, on-chip optical frequency comb generation, and coherent beat note generation at 45 GHz. These advancements result in compact form factors, reduced power consumption, and enhanced scalability, positioning PICs as an enabling technology for future high-speed wireless networks. Full article

Uncrystallized indium-gallium-zinc-oxide (InGaZnO) thin-film transistors (TFTs) combined with an aluminum nitride (AlN) dielectric have been used to promote performance and steadiness. However, the high deposition temperature of AlN films limits their application in InGaZnO flexible TFTs. In this work, AlN layers were deposited via low-temperature plasma-enhanced atomic layer deposition (PEALD), and InGaZnO films were fabricated via high-power impulse magnetron sputtering (HIPIMS). The band alignment of the AlN/InGaZnO heterojunction was studied using the X-ray photoemission spectrum and ultraviolet visible transmittance spectrum. It was found that the AlN/InGaZnO system exhibited a staggered band alignment with a valence band offset ΔE_v of −1.25 ± 0.05 eV and a conduction band offset ΔE_c of 4.01 ± 0.05 eV. The results imply that PEALD AlN could be more useful for surface passivation than a gate dielectric to promote InGaZnO device reliability under atmospheric exposure. Full article

This study presents an innovative method for the synthesis of indium aluminum nitride (InAlN) layers by direct current (DC) co-sputtering at room temperature, with the aim of reducing production costs of optoelectronic devices. Indium and aluminum targets are used, varying the power applied to the aluminum target. The results show that increasing the target power favors the formation of aluminum nitride (AlN), which modifies the chemical composition of the material. The layers obtained present smooth surfaces with a roughness of less than 3 nm, which is beneficial for applications requiring interfaces with low defect density. Regarding the optical properties, it is observed that the optical bandgap varies between 1.8 eV and 2.0 eV, increasing with the target power. Hall effect measurements indicate a decrease in the free carrier concentration and an increase in the resistivity with increasing power. This approach allows for the synthesis of InAlN with properties suitable for optoelectronic applications, solar cells, photocatalysis, and photoelectrocatalysis at low cost. Full article

It is expected that two-dimensional (2D) metal nitrides (MNs) consisting of the 13th group elements of the periodic table and nitrogen, namely aluminium nitride (AlN), gallium nitride (GaN), indium nitride (InN) and thallium nitride (TlN), have enhanced physical and mechanical properties due to the honeycomb, graphene-like atomic arrangement characteristic of these compounds. The basis for the correct design and improved performance of nanodevices and complex structures based on 2D MNs from the 13th group is an understanding of the mechanical response of their components. In this context, a comparative study to determine the elastic properties of metal nitride nanosheets was carried out making use of the nanoscale continuum modelling (or molecular structural mechanics) method. The differences in the elastic properties (surface shear and Young’s moduli and Poisson’s ratio) found for the 2D 13th group MNs are attributed to the bond length of the respective hexagonal lattice of their diatomic nanostructure. The outcomes obtained contribute to a benchmark in the evaluation of the mechanical properties of AlN, GaN, InN and TlN monolayers using analytical and numerical approaches. Full article

Selective CO₂ hydrogenation faces significant technical challenges, although many efforts have been made in this regard. Herein, a Ni-doped In₂O₃ catalyst supported by g-C₃N₄ was prepared using the co-precipitation method, and its composition, morphology, specific surface area, and band gap were characterized using TEM, XPS, BET, XRD, CO₂-TPD, H₂-TPR, UV-Vis, etc. The catalytic hydrogenation reduction of CO₂ to produce methanol was tested. Under low-photothermal conditions (1.0 MPa), the hydrogenation of carbon dioxide to methanol is stable, effective, and highly selective, with a spatiotemporal yield of 86.0 g_MeOHh⁻¹ kg_cat⁻¹, which is 30.9% higher than that of Ni-In₂O₃ without g-C₃N₄ loading under the same conditions. Full article

In this work, two different composite nanostructures, YAG:Ce and Ga_0.9In_0.1N, were prepared by the Urea Glass Route method and tested for the production of white light. The first composite was prepared by synthetizing the Ga_0.9In_0.1N nanoparticles in the presence of YAG:Ce nanoparticles. The second one was prepared by synthetizing YAG:Ce nanoparticles in the presence of Ga_0.9In_0.1N nanoparticles. These systems can be useful for the production of white light. X-ray Diffraction and Transmission and Scanning Electron Microscopies (TEM and SEM) were used to evaluate their structural and morphological properties. Excitation and emission spectra, the quantum yield and colour of the emitted light were acquired to evaluate the optical properties of the systems. Full article

Gallium nitride (GaN) semiconductors and their broadband InGaN alloys in their hexagonal phase have been extensively studied over the past 30 years and have allowed the development of blue-ray lasers, which are essential disruptive developments. In addition to high-efficiency white light-emitting diodes, which have revolutionized lighting technologies and generated a great industry around these semiconductors, several transistors have been developed that take advantage of the characteristics of these semiconductors. These include power transistors for high-frequency applications and high-power transistors for power electronics, among other devices, which have far superior achievements. However, less effort has been devoted to studying GaN and InGaN alloys grown in the cubic phase. The metastable or cubic phase of III-N alloys has superior characteristics compared to the hexagonal phase, mainly because of the excellent symmetry. It can be used to improve lighting technologies and develop other devices. Indium gallium nitride, In_xGa_1−xN alloy, has a variable band interval of 0.7 to 3.4 eV that covers almost the entire solar spectrum, making it a suitable material for increasing the efficiencies of photovoltaic devices. In this study, we successfully synthesized high-quality cubic InGaN films on MgO (100) substrates using plasma-assisted molecular beam epitaxy (PAMBE), demonstrating tunable emissions across the visible spectrum by varying the indium concentration. We significantly reduced the defect density and enhanced the crystalline quality by using an intermediate cubic GaN buffer layer. We not only developed a heterostructure with four GaN/InGaN/GaN quantum wells, achieving violet, blue, yellow, and red emissions, but also highlighted the immense potential of cubic InGaN films for high-efficiency light-emitting diodes and photovoltaic devices. Achieving better p-type doping levels is crucial for realizing diodes with excellent performance, and our findings will pave the way for this advancement. Full article

Extensive ab initio density functional theory molecular dynamics calculations were used to evaluate stability conditions for relevant phases of InN. In particular, the p-T conditions of the thermal decomposition of InN and pressure-induced wurtzite–rocksalt solid–solid phase transition were established. The comparison of the simulation results with the available experimental data allowed for a critical evaluation of the capabilities and limitations of the proposed simulation method. It is shown that ab initio molecular dynamics can be used as an efficient tool for simulations of phase transformations of InN, including solid–solid structural transition and thermal decomposition with formation of N₂ molecules. It is of high interest, because InN is an important component of epitaxial quantum structures, but it has not been obtained as a bulk single crystal. This makes it difficult to determine its basic physical properties to develop new applications. Full article

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfO_xN_y on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were −1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications. Full article

The utilization of optical antennas for active control of far-field radiation at the subwavelength scale is crucial in various scientific and technological applications. We propose a thermally tunable disk design of indium tin oxide (ITO) and aluminum gallium nitride (${\mathrm{Al}}_{0.18}{\mathrm{Ga}}_{0.82}\mathrm{As}$), enabling a switch between absorption and scattering. Furthermore, the control of far-field radiation pattern can be easily realized by combining ITO and ${\mathrm{Al}}_{0.18}{\mathrm{Ga}}_{0.82}\mathrm{As}$ to enhance or suppress emission. Our results demonstrate that hybrid structures can be dynamically tuned with temperature variations. In the proposed design, a frequency is achieved at the wavelength of 1240 nm. The thermal tunability of hybrid structures introduces new multifunctional possibilities for light manipulation, thereby enhancing the potential applications of new devices in the near-infrared range. Full article

In recent years, tubular nanostructures have been related to immense advances in various fields of science and technology. Considerable research efforts have been centred on the theoretical prediction and manufacturing of non-carbon nanotubes (NTs), which meet modern requirements for the development of novel devices and systems. In this context, diatomic inorganic nanotubes formed by atoms of elements from the 13th group of the periodic table (B, Al, Ga, In, Tl) and nitrogen (N) have received much research attention. In this study, the elastic properties of single-walled boron nitride, aluminium nitride, gallium nitride, indium nitride, and thallium nitride nanotubes were assessed numerically using the nanoscale continuum modelling approach (also called molecular structural mechanics). The elastic properties (rigidities, surface Young’s and shear moduli, and Poisson’s ratio) of nitride nanotubes are discussed with respect to the bond length of the corresponding diatomic hexagonal lattice. The results obtained contribute to a better understanding of the mechanical response of nitride compound-based nanotubes, covering a broad range, from the well-studied boron nitride NTs to the hypothetical thallium nitride NTs. Full article

Highly indium-rich group-III nitrides are attracting attention for advancing our capacity to create highly effective optical emitters at extended visible/IR wavelengths or for enhancing bandgap engineering possibilities within the group-III nitride material framework. Current methods of synthesis are constrained in their efficacy, partially owing to the low decomposition temperature of indium nitride. Implementation of a new design of a vertical high-pressure spatial chemical vapor deposition (HPS-CVD) reactor with six separated precursor source zones and a rotating wafer carrier disk carrying four 2-inch wafers is proposed and analyzed using COMSOL Multiphysics as a commercial computational fluid dynamics (CFD) program to study the fluid phenomena inside the numerical domain. This study focuses on understanding the different flow patterns within the chambers at super-atmospheric conditions (5 atm to 30 atm) and identifying suitable operating conditions under which smooth and dominant vortex-free flow is achieved. Four 2-inch wafers are heated to maintain a temperature of 1200–1300 K at each pressure and gas type. Three different gas types (nitrogen, hydrogen, and ammonia) are used, and the impacts of different inlet flow velocities and rotational speeds are investigated and discussed. An operating matrix is presented for each analyzed system pressure providing suitable combinations of these operational variables for smooth flow in the chambers. Each gas type was identified to have a range of suitable rotational and inlet velocity regimes at each operating pressure. Overlap of these three gas-specific operating condition windows resulted in the identification of a generally suitable operating condition for smooth flow patterns in the system regardless of the gas type used, as required for the growth of group-III nitride materials. Full article

Indium nitride is an excellent semiconductor that belongs to the group of III nitride materials. Due to its unique properties, it is applied to various optoelectronic applications. However, its low thermal stability makes it difficult to synthesize. The present study introduces the synthesis of indium nitride nanoparticles, using ultrasound power (sonochemistry). The sonochemical method provides a low-cost and rapid technique for nanomaterial synthesis. InN nanoparticles were produced in only 3 h through the sonochemical reaction of InCl₃ and LiN₃. Xylene was used as a reaction solvent. X-ray powder diffraction (XRD) as well as high-resolution transmission electron microscopy (HRTEM) were adopted for the characterization of the obtained powder. According to our results, ultrasound contributed to the synthesis of InN nanocrystals in a cubic and a hexagonal phase. The obtained InN nanoparticles were further used to decorate titanium dioxide (TiO₂) by means of ultrasound. The contribution of InN nanoparticles on the processes of photocatalysis was investigated through the degradation of methylene blue (MB), a typical organic substance acting in place of an environment pollutant. According to the obtained results, InN nanoparticles improved the photocatalytic activity of TiO₂ by 41.8% compared with commercial micrometric titania. Full article

GaN heterostructure is a promising material for next-generation optoelectronic devices, and Indium gallium nitride (InGaN) has been widely used in ultraviolet and blue light emission. However, its applied potential for longer wavelengths still requires exploration. In this work, the ultra-thin InN/GaN superlattices (SL) were designed for long-wavelength light emission and investigated by first-principles simulations. The crystallographic and electronic properties of SL were comprehensively studied, especially the strain state of InN well layers in SL. Different strain states of InN layers were applied to modulate the bandgap of the SL, and the designed InN/GaN heterostructure could theoretically achieve photon emission of at least 650 nm. Additionally, we found the SL had different quantum confinement effects on electrons and holes, but an efficient capture of electron-hole pairs could be realized. Meanwhile, external forces were also considered. The orbital compositions of the valence band maximum (VBM) were changed with the increase in tensile stress. The transverse electric (TE) mode was found to play a leading role in light emission in normal working conditions, and it was advantageous for light extraction. The capacity of ultra-thin InN/GaN SL on long-wavelength light emission was theoretically investigated. Full article