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GaN-based tunnel-oxide-free charge trapping memory (CTM) that exploits deep-level interface states and large junction barriers for charge storage has been demonstrated, exhibiting high speed, high endurance, and long retention time. To enhance the data storage capacity, high-density deep-level states at the charge-trapping interface are required. In this letter, we demonstrate the multi-state operation of a GaN-based CTM with an AlN interfacial layer prepared by plasma-enhanced atomic layer deposition (PEALD). The thin PEALD-AlN interfacial layer, positioned between the Al2O3 and the p-GaN channel, increases the memory window (MW) due to the formation of high-density interface states. Post-metallization annealing performed in N2 ambient at 420 C improves charge retention, with an extrapolated room-temperature retention time exceeding 109 s. Based on these, the GaN-based CTM achieves a large MW over 5 V, 2-bit/cell operation, and long-term analog-state storage. © 1980-2012 IEEE.

Aluminum nitride (AlN) is a material of growing interest for power electronics, fabrication of sensors, micro-electromechanical systems, and piezoelectric generators. For the latter, the formation of nanowire arrays or nanostructured films is one of the emerging research directions. In the current work, nanostructured AlN films manufactured with normal and glancing angle magnetron sputter depositions have been investigated with scanning and transmission electron microscopy, X-ray diffraction, atomic force microscopy, and optical spectroscopy. Growth of the nanostructures was realized utilizing metal seed particles (Ag, Au, and Al), allowing the control of the nucleation and following growth of AlN. It was demonstrated how variations of seed particle material and size can be used to tune the parameters of nanostructures and morphology of the AlN films. Using normal angle deposition allowed the growth of bud-shaped structures, which consisted of pillars/lamellae with wurtzite-like crystalline structures. Deposition at a glancing angle of 85° led to a film of individual nanostructures located near each other and tilted at an angle of 33 degree; relative to the surface normal. Such films maintained a high degree of wurtzite-like crystallinity but had a more open structure and higher roughness than the nanostructured films grown at normal incidence deposition. The developed production strategies and recipes for controlling parameters of nanostructured films pave the way for the formation of matrices to be used in piezoelectric applications., Novo Nordisk Foundation

Aluminum nitride (AlN) and boron nitride (BN) are well-known ceramic materials with numerous valuable properties, whereas recently there is a growing field of research on the AlN/BN advanced ceramic materials. Here, we present a study on boron-rich AlN, structural and electronic properties, and structure–property relationship. Several AlxB1−xN solid solutions (x = 1, .875, .75, and .625) have been investigated, and structure optimization has been performed for four different structure types: h-BN, wurtzite, sphalerite, and rock salt. First-principles calculations were performed using hybrid B3LYP functional. New modifications and compounds have been predicted as a function of boron concentration in AlN, and especially, interesting phase transitions were found at extreme pressure conditions. Electronic properties and band structures were computed, and the possibility for bandgap tuning has been discovered. The present study, and especially the structure–property relationship, gives new possibilities for bandgap engineering in boron-rich AlN electroceramic materials.

A quantitative description of the excited electronic states of point defects and impurities is crucial for understanding materials properties, and possible applications of defects in quantum technologies. This is a considerable challenge for computational methods, since Kohn-Sham density functional theory (DFT) is inherently a ground-state theory, while higher-level methods are often too computationally expensive for defect systems. Recently, embedding approaches have been applied that treat defect states with many-body methods, while using DFT to describe the bulk host material. We implement such an embedding method, based on Wannierization of defect orbitals and the constrained random-phase approximation approach, and perform systematic characterization of the method for three distinct systems with current technological relevance: a carbon dimer replacing a B and N pair in bulk hexagonal BN (CBCN), the negatively charged nitrogen-vacancy center in diamond (NV-), and an Fe impurity on the Al site in wurtzite AlN (FeAl). In the context of these test-case defects, we demonstrate that crucial considerations of the methodology include convergence of the bulk screening of the active-space Coulomb interaction, the choice of exchange-correlation functional for the initial DFT calculation, and the treatment of the "double-counting"correction. For CBCN we show that the embedding approach gives many-body states in agreement with analytical results on the Hubbard dimer model, which allows us to elucidate the effects of the DFT functional and double-counting correction. For the NV- center, our method demonstrates good quantitative agreement with experiments for the zero-phonon line of the triplet-triplet transition. Finally, we illustrate challenges associated with this method for determining the energies and orderings of the complex spin multiplets in FeAl. © 2022 American Physical Society.

Lithium germanium thiophosphate (LGPS) is an attractive solid-state electrolyte material due to its exceptionally high ionic conductivity, which rivals organic liquid electrolytes. Despite this potential, other properties have impeded its adoption into solid-state batteries, particularly the poor voltage stability of the material at potentials near that of high voltage cathodes or lithium metal. Aluminum nitride (AlN) can serve as an anodic protection interlayer between LGPS and lithium metal, enhancing cell performance. AlN is grown via plasma-enhanced ALD at 250 °C using TMA and both N2 and NH3, but the deposited films show significant oxygen contamination originating from the plasma and lack crystallinity. Galvanostatic cycling and electrochemical impedance spectroscopy show that LGPS-coated cells perform better than bare cells, with expected lifetimes >3x greater in certain cases. Finally, XPS line scans highlight the slow room-temperature reactivity between AlN and evaporated lithium, and a computational model is built to aid further XPS experiments.

У рукопису запропоновано метод моделювання і аналізу імпульсних та високочастотних властивостей багатодолинних напівпровідників. Модель застосовано до сучасних, актуальних і, як буде доведено у тому числі у рукописі, перспективних напівпровідникових матеріалів GaN, AlN і InN, які зараз все більше стають відомі під узагальнюючою назвою III-нітриди. Метод відрізняється можливістю застосування одночасно як для динамічних задач у часі, так і змінних у просторі полів та збалансованим використанням обчислювальних ресурсів без істотних втрат точності. Базисом запропонованого підходу є чисельне рішення системи диференціальних рівнянь, які отримані з кінетичного рівняння Больцмана у наближенні часу релаксації по функції розподілу у k-просторі. Ці рівняння відомі під узагальненою назвою релаксаційних. В англомовній літературі цей метод зустрічається під назвою «Method of moments» (метод моментів). Але на відміну від традиційного використання рівнянь для концентрації носіїв, їх імпульсу і енергії у праці використано замість рівняння релаксації енергії рівняння для електронної температури як міри середньої енергії тільки хаотичного руху. Друга принципова відмінність полягає в тому, що часи релаксації визначаються через усереднення квантовомеханічних швидкостей розсіювання, зазвичай використовуваних у методі Монте-Карло, для окремих видів розсіювання, а не як інтегральні значення із статичних характеристик матеріалу. Різні механізми розсіювання носіїв враховуються через специфічні для них часи релаксації за допомогою проведення усереднення за максвеллівською функцією розподілу в наближенні електронної температури. Система отриманих рівнянь включає рівняння у частинних похідних як за часом так і за координатами, що дає можливість дослідити характерні прояви імпульсних властивостей напівпровідникових матеріалів, зокрема: «балістичний транспорт» носіїв у просторі та ефект «сплеску» дрейфової швидкості у часі. Вперше розглянуто використання Фур’є-перетворення імпульсної залежності д

У рукопису запропоновано метод моделювання і аналізу імпульсних та високочастотних властивостей багатодолинних напівпровідників. Модель застосовано до сучасних, актуальних і, як буде доведено у тому числі у рукописі, перспективних напівпровідникових матеріалів GaN, AlN і InN, які зараз все більше стають відомі під узагальнюючою назвою III-нітриди. Метод відрізняється можливістю застосування одночасно як для динамічних задач у часі, так і змінних у просторі полів та збалансованим використанням обчислювальних ресурсів без істотних втрат точності. Базисом запропонованого підходу є чисельне рішення системи диференціальних рівнянь, які отримані з кінетичного рівняння Больцмана у наближенні часу релаксації по функції розподілу у k-просторі. Ці рівняння відомі під узагальненою назвою релаксаційних. В англомовній літературі цей метод зустрічається під назвою «Method of moments» (метод моментів). Але на відміну від традиційного використання рівнянь для концентрації носіїв, їх імпульсу і енергії у праці використано замість рівняння релаксації енергії рівняння для електронної температури як міри середньої енергії тільки хаотичного руху. Друга принципова відмінність полягає в тому, що часи релаксації визначаються через усереднення квантовомеханічних швидкостей розсіювання, зазвичай використовуваних у методі Монте-Карло, для окремих видів розсіювання, а не як інтегральні значення із статичних характеристик матеріалу. Різні механізми розсіювання носіїв враховуються через специфічні для них часи релаксації за допомогою проведення усереднення за максвеллівською функцією розподілу в наближенні електронної температури. Система отриманих рівнянь включає рівняння у частинних похідних як за часом так і за координатами, що дає можливість дослідити характерні прояви імпульсних властивостей напівпровідникових матеріалів, зокрема: «балістичний транспорт» носіїв у просторі та ефект «сплеску» дрейфової швидкості у часі. Вперше розглянуто використання Фур’є-перетворення імпульсної залежності д, The dissertation work proposed a method for modeling and interpreting the high-frequency characteristics of multi-valley semiconductors, in particular, GaN, AlN, and InN. The model is practiced to state-of-the-art, encouraging, and relevant materials GaN, AlN, and InN, which are now recognized under the generic name III-nitrides. The method is noticed by the economical use of computational resources without meaningful loss of accuracy and the feasibility of using both for dynamic tasks over time and variables in the scope of fields. The introduced approach is based on solving a system of differential equating, which are known as relaxation equations and are obtained from the Boltzmann kinetic equating in the relaxation time approximation by averaging over k-space. In English literature, this method is known as the "method of momentum." Indifference to the traditional system of equations for the concentration of carriers, their momentum, and energy, here, alternately of the energy relaxation equation, the equation for electron temperature is done as a measure of the energy of only chaotic movement. The second meaningful difference is that the relaxation times are not defined as integral values from the static properties of the material, but for averaging the quantum-mechanical scattering rates usually used in the Monte Carlo meth-od for particular types of scattering. The averaging was made over the Maxwell distribution function in the electron temperature approximation, as an outcome of which numerous mechanisms of carrier scattering through their explicit relaxation times are taken into account. Since the system of equations applied includes equations in partial derivatives concerning time and coordinates, it performs it possible to examine the characteristic demonstrations of the impulse properties of the mate-rials under consideration, particularly, the time effect of the “overshoot” of drift velocity and the spatial “ballistic transport” of carriers. For the fir

The present work compared the initial stages of corrosion process development on the AM60-AlN metal matrix nanocomposite surface and on AM60, during their exposure for 30 days to simulated acid rain solution (SAR). The AlN nanoparticles were observed as “attached” to those of Mn-rich AlMn intermetallic particles, forming clusters. The introduction of 1.0 wt.% AlN (≈ 80 nm) in the AM60 alloy carried a slight grain refinement and favored the formation of a denser and more protective corrosion layer, suggested by the electrochemical impedance spectroscopy (EIS) values of higher charge transfer resistance (R2) and capacitance, characteristic of the double layer in the presence of corrosion products, and also suggested by Rn (EN) values, compared to those of the AM60 alloy. Thus, the concentration of the released Mg-ions from the composite surface was lower. Due to the increase in time of the SAR solution pH, Al de-alloying may occur, as well as Al(OH) formation, as confirmed by XPS analysis. Due to the presence of Cl-ions in SAR solution, localized corrosion was observed, suggested as fractional Gaussian noise of a stationary and persistent process in time, according to the PSD of the corrosion current fluctuations (EN).

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

AlN-based ceramics have great prospects for use in the field of structural materials for reactors of the new generation of GenIV, as well as dosimetric and optical devices. Interest in them is due to their unique physical and chemical properties, high resistance to degradation and excellent insulating properties. This work is devoted to the study of changes in the optical and heat-conducting properties of AlN ceramics as a result of irradiation with Kr15+ and Xe22+ heavy ions with energies close to those of fission fragments of uranium nuclei, and fluences 1014–1015 ion/cm2. During the study, dose relationships of changes in the optical properties of ceramics were established, as well as the effect of the type of ions on the degree of radiation damage and deterioration of optical characteristics. It has been found that an increase in the irradiation dose for Kr15+ ions leads to a slight increase in the depth of electron traps, while for samples irradiated with Xe22+ ions there is a sharp increase in the depth of occurrence from 5 to 20%, depending on the irradiation dose. For samples irradiated with Xe22+ ions, the greatest decrease in thermal conductivity was 19%, while for ceramics irradiated with Kr15+ ions, the maximum decrease was not more than 10%. The results show a significant resistance of ceramics to radiation damage by Kr15+ ions and negative effects, leading to a decrease in the resistance of optical and conductive properties of ceramics when irradiated with Xe22+ ions with doses higher than 5 × 1014 ion/cm2. Using the X-ray diffraction method, the dependences of structural distortions and changes in dislocation density in the structure of ceramics on the radiation dose were established. It has been determined that the main structural changes are associated with the fragmentation of grains, which result in an increase in the dislocation density, as well as deformation and distortion of the crystal lattice as a result of the formation of complex defects i

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently, there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements, in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method, it may form different bonds with nitrogen, e.g. amino (–NH2) or imide (–NH) groups, which impair the quality of the resulting film. Which is why, it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors, substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM, XPS and EDS to provide a comparative and comprehensive analysis of topography, morphology and chemical composition of AlN thin films.

The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

The aim of this study is to investigate the hydrogen impregnations in AlN thin films deposited using plasma-enhanced atomic layer deposition technique. As of date, there is an apparent gap in the literature regarding the matter of hydrogen impregnation within the AlN layers. Hydrogen is a frequent contaminant and its content has detrimental effect on the quality of resulted layer, which is why it is relevant to investigate this particular contaminant and try to eliminate or at least minimize its quantity. Within the films hydrogen commonly forms amino or imide types of bonds (–NH2, - NH). There is only a handful of analytical methods enabling the detection of hydrogen. This particular study comprises two of them – Fourier-transform infrared spectroscopy (FTIR) and second ion-mass spectrometry (SIMS). XPS analysis has also been included to examine the surface nature and structural imperfections of the grown layer.

[EN] The improvement of heat dissipation in electronic and energy devices is a challenge that can be addressed through the use of highly porous materials. Presently, the additive manufacturing of 3D aluminum nitride is described, and different lattice patterns with porosities in the range 45–64 % are achieved by direct ink writing. All the structures are robust and the effective thermal conductivity (k) for cuboid structures decreases by 50–75 % with the filament separation and shows anisotropic characteristics, since k along the longitudinal axis of the scaffold is up to six times greater than for the transversal one. Heat transfer during free cooling experiments for cuboid and cylinder scaffolds, after rapid heating at temperatures above 1000 °C, takes place by radiation for temperatures >500 °C and by convection through the complete cooling process. The heat dissipation time constants of both processes decrease almost linearly with the designed scaffold parameters of porosity and rod separation.

Low surface roughness, low residual stress, and(002) textured aluminum nitride(AlN) thin films are favored for applications in microelectronic and optoelectronic devices. In this paper, AlN thin films were deposited by reactive high power pulsed magnetron sputtering(HPPMS). The effect of aluminum target sputtering mode and sputtering power on thin film residual stress, crystalline structure, surface roughness, and morphology of AlN thin films was studied. The results indicate that, with Al target sputtering mode transfer from metallic mode to transitional and compound modes, respectively, the number of Al species decrease, and ion-to-neutral ratio of Al species increase. Comparing the AIN thin film deposited in compound mode with that deposited in transitional mode, the latter exhibited lower surface roughness and residual stress. In addition, AlN thin film with (002) texture and lower residual stress is obtained by increasing sputtering power in transitional mode. For fabricating AIN film via reactive HPPMS with a particular (002) texture, low surface roughness, and residual stress, sputtering the target in the transitional mode with high sputtering power is optimal.

Aluminum nitride (AlN) has a unique combination of properties, such as high chemical and thermal stability, nontoxicity, high melting point, large energy band gap, high thermal conductivity, and intensive light emission. This combination makes AlN nanowires (NWs) a prospective material for optoelectronic and field-emission nanodevices. However, there has been very limited information on mechanical properties of AlN NWs that is essential for their reliable utilization in modern technologies. Herein, we thoroughly study mechanical properties of individual AlN NWs using direct, in situ bending and tensile tests inside a high-resolution TEM. Overall, 22 individual NWs have been tested, and a strong dependence of their Young's moduli and ultimate tensile strengths (UTS) on their growth axis crystallographic orientation is documented. The Young's modulus of NWs grown along the [1011] orientation is found to be in a range 160-260 GPa, whereas for those grown along the [0002] orientation it falls within a range 350-440 GPa. In situ TEM tensile tests demonstrate the UTS values up to 8.2 GPa for the [0002]-oriented NWs, which is more than 20 times larger than that of a bulk AlN compound. Such properties make AlN nanowires a highly promising material for the reinforcing applications in metal matrix and other composites. Finally, experimental results were compared and verified under a density functional theory simulation, which shows the pronounced effect of growth axis on the AlN NW mechanical behavior. The modeling reveals that with an increasing NW width the Young's modulus tends to approach the elastic constants of a bulk material.

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The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

The aim of this work is to study topography and chemical composition of AlN thin films deposited on Si substrates previously exposed to various time of thermal processing using plasma-enhanced atomic layer deposition technique. The samples were heated up to 500 °C for the period of 2 and 4 hours. Chemical composition of wafers and the films obtained are provided by Xray photoelectron spectroscopy (XPS). Surface topography was investigated using atomic force microscopy (AFM).

This work applies a comprehensive nonlinear characterization process of two Temperature Compensated Bulk Acoustic Wave (TC-BAW) resonators. In both resonators, the SiO 2 layers have a remarkable impact on the generation of third- order intermodulation products (IMD3), confirming the impact of the SiO 2 on the generation of passive intermodulation. A unified model considering the electro-thermo-mechanical constitutive relations of the piezoelectricity is used, that allows to discern on the origin of the IMD3, either it comes from intrinsic nonlinearities of the materials, or from self-heating mechanisms., This work was supported in part through grants TEC2017-84817-C2-2-R, TEC2017-88343-C4-2-R and 2017 SGR 813. With the support of the Universities and Research Secretary of the Generalitat de Catalunya and the European Social Fund through grant 2018FI_B_00448, Peer Reviewed, Postprint (published version)

This paper is devoted to the discussion of the experimental results on the solid-phase synthesis of the nitride material ZrN-AlN. A mixture of powders of metallic zirconium and aluminum nitride was heated by means of microwave radiation in a nitrogen atmosphere for 90 minutes. Phase composition by sample volume and electron microscopy of the surface were studied to confirm the solid-phase reaction of zirconium with aluminum nitride. Thermodynamic calculations showed that several possible processes happen at once and lead to the formation of the nitride material ZrN-AlN in a nitrogen atmosphere. Experimental results showed a relatively low content of zirconium nitride (32.8 mol.%) and a significant content of metallic zirconium residues (8.8 at.%) in the upper layers of the sample despite contact with the gas phase. While in the sample volume, the conversion of metallic zirconium to nitride was almost complete (the content is 74.9 mol.%). Experimental observations have shown that, due to microwave heating, the formation of characteristic coral-like growths on the surface of particles with the concentration of chemical impurities, due to the purity of the initial reagents, is evident. © Published under licence by IOP Publishing Ltd.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

In this work we used atomic layer deposition (ALD) method to obtain thin films of AlN using tris(diethylamido)aluminum (III) (TDEAA) with hydrazine (N2H4) or ammonia (NH3) as precursors. Elemental analysis of the film deposited by ALD TDEAA /N2H4 at 200 °C showed the presence of carbon impurities ~ 1.4 at%, oxygen ~ 3.2 at.% and hydrogen 22.6 at.%. The atomic concentration ratio of N/Al was ~ 1.3. The residual impurities content with N2H4 was lower than with NH3. In general, it has been confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.

The design and ventilation system features of a small enclosed diesel generator with combined multi-functional brushless exciter, results of the generator thermal stability analisys as well as the opportunities of design progress application in other capability and enclosure type generators are presented in the paper.

Nanocrystalline aluminum nitride (AlN) thin films were deposited on two types of metallic seed layers on silicon substrates, (111) textured Pt and (110) Mo, by reactive DC magnetron sputtering at low temperature (200 °C). Both textured films of Pt and Mo promote nucleation, thereby improving the crystallinity and epitaxial growth condition for AlN thin films. The deposited films were examined by X-ray diffraction, scanning electron microscopy and atomic force microscopy techniques. The results indicated that the preferred orientation of crystallites greatly depends upon the kinetic energy of the sputtered species (target power) and seed layers used. Furthermore, AlN thin films with c-axis perpendicular to the substrate grew on both types of metal electrodes at all power levels larger than 100 W. By comparing the structural properties and compressive stresses at perfect c-axis orientation conditions, it is evident that AlN films deposited on (110) oriented Mo substrates exhibited superior properties as compared with Pt/Ti seed layers. Furthermore, less values of compressive stresses (−3 GPa) as compared with Pt/Ti substrates (−7.08 GPa) make Mo preferentially better candidate to be employed in the field of suspended Micro/Nano - electromechanical systems (MEMS/NEMS) for piezoelectric devices., QC 20171218

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), Griffith School of Engineering, Science, Environment, Engineering and Technology, The growth of micro-scale wireless electronics is increasing significantly because of their miniaturisation and low power consumption. These devices currently draw power from batteries or chemical fuel cells. Their limited life-spans prompt active research to find an alternative solution by harvesting ambient energy from the environment. Numerous sources are available such as solar, thermoelectric, acoustic, and mechanical vibrations. Among them, mechanical vibration is perhaps the most practical to power these wireless electronic devices via piezoelectric transduction. Three most common piezoelectric materials are Lead zirconate titanate (PZT), zinc oxide (ZnO) and aluminum nitride (AlN). AlN is preferred over ZnO and PZT for several reasons. Chiefly among them is because it has the highest electromechanical coupling along the c-axis of wurzite AlN for longitudinal deformation. This thesis investigates the sputtering of c-axis oriented AlN on top of cubic-silicon carbide-on-silicon (3C-SiC-on-Si) substrates for piezoelectric applications. The 3C-SiC buffer layer was used to reduce the lattice mismatch and thermal expansion coefficient between AlN and Si. In the first part of the research, RF sputtering was utilised for depositing AlN. The low growth rate of RF sputtering prompted the switch to DC sputtering. The DC sputtering suffered from electrical arching problems, which were addressed by gradually decreasing the sputtering pressure. However, the system had the limitation of 1200 W of maximum power.

Epoxy composites containing boron nitride (BN) or aluminum nitride (AlN or Al2N3) particles have been studied with a view to obtaining increased thermal conductivity. The effect of these fillers on the cure reaction has been investigated by differential scanning calorimetry (DSC) for two systems, epoxy-diamine and epoxy-thiol, and for volume fractions up to about 35 % of these filler particles. For the epoxy-diamine system, the glass transition temperature of the fully cured system, the heat of reaction, and the temperature at which the peak heat flow occurs were all independent of the cure conditions, filler type and content. In contrast, the epoxy-thiol system shows a systematic effect of filler on the peak temperature for both fillers: there is an initial acceleration of the reaction, which diminishes with increasing content, and the reaction is even significantly retarded at high contents for BN. This is interpreted in terms of an improved interface between epoxy matrix and particles, with a consequent enhancement of the thermal conductivity of the epoxy-thiol composites., Peer Reviewed, Postprint (published version)

The growth of micro-scale wireless electronics is increasing significantly because of their miniaturisation and low power consumption. These devices currently draw power from batteries or chemical fuel cells. Their limited life-spans prompt active research to find an alternative solution by harvesting ambient energy from the environment. Numerous sources are available such as solar, thermoelectric, acoustic, and mechanical vibrations. Among them, mechanical vibration is perhaps the most practical to power these wireless electronic devices via piezoelectric transduction. Three most common piezoelectric materials are Lead zirconate titanate (PZT), zinc oxide (ZnO) and aluminum nitride (AlN). AlN is preferred over ZnO and PZT for several reasons. Chiefly among them is because it has the highest electromechanical coupling along the c-axis of wurzite AlN for longitudinal deformation. This thesis investigates the sputtering of c-axis oriented AlN on top of cubic-silicon carbide-on-silicon (3C-SiC-on-Si) substrates for piezoelectric applications. The 3C-SiC buffer layer was used to reduce the lattice mismatch and thermal expansion coefficient between AlN and Si. In the first part of the research, RF sputtering was utilised for depositing AlN. The low growth rate of RF sputtering prompted the switch to DC sputtering. The DC sputtering suffered from electrical arching problems, which were addressed by gradually decreasing the sputtering pressure. However, the system had the limitation of 1200 W of maximum power., Thesis (PhD Doctorate), Doctor of Philosophy (PhD), Griffith School of Engineering, Science, Environment, Engineering and Technology, Full Text

This paper presents two types of coplanar transitions based on aluminum nitride (AlN) substrate for interposer designs of terabit transceivers. The designs of coupled coplanar waveguide (CCPW), coupled line, coplanar waveguide (CPW), and coplanar stripline (CPS) based on AlN substrate are explained. The effects of absorber layer and wire bonding bridges are described. Two types of coplanar transitions are designed and simulated in back-to-back configuration with wire bonding bridges. When driven by differential signal pair, the proposed CCPW-to-coupled line transition in back-to-back configuration with wire bonding bridges achieves a simulated return loss of 11 dB and insertion loss of 2 dB up to 110 GHz. As for single-ended signals, a CPW-to-CPS transition in back-to-back configuration with wire bonding bridges has been designed, fabricated, and measured. The fabricated CPW-to-CPS transition can provide a −3 dB transmission bandwidth up to 80 GHz with associated return loss better than 12 dB.