Gallium Atoms Research Articles

Ten-Membered Cyclodecatetraene Derivatives Including Two Gallium Atoms: Experimental and Theoretical Studies on Synthesis, Structures, and Their Transformations to Nine- and Five-Membered Gallacycles

The chemistry of medium-sized ring compounds, including group 13 elements, has scarcely been investigated. Herein, we report that 5,10-digallacyclodeca-1,3,6,8-tetraene derivatives Cl2Ga2C8R8 (R = Me (5a), Et (5b)) can be obtained by the reaction of GaCl3 and zirconacyclopentadiene Cp2ZrC4R4 (R = Me (2a), Et (2b), Cp: η5-C5H5) in toluene. X-ray crystal structure analysis revealed that compound 5b has a 10-membered cyclodecatetraene structure composed of two butadiene skeletons and two GaCl fragments. X-ray crystal structure analysis and IR measurement confirmed that compound 5b forms Ga2Cl2 four-membered rings via intermolecular Cl to Ga donor–acceptor interactions, which result in the formation of oligomeric chain structures in the solid state and toluene solution. The treatment of compound 5b with 2 equivalents of 4-(dimethylamino)pyridine (DMAP) proceeded via the coordination of DMAP to the Ga center and the ring contraction to give DMAP-coordinated five-membered gallole Cl(DMAP)GaC4Et4 (4bDMAP). The reaction of compound 5a with 2 equivalents of MesLi (Mes: 2,4,6-Me3C6H2) in toluene to form a 9,10-digallabicyclo[4.3.1]decatriene derivative (MesGaC8Me8)GaMes (6a) caused ring contraction. Theoretical investigation revealed that the 10-membered ring derivative, Cl2Ga2C8H8 (GaH-10), is formed by the dimerization of two gallole molecules, ClGaC4H4 (GaH-5), via the addition of two Ga–C bonds without an energy barrier. The immediate formation of GaH-10 was attributed to the transannular electronic interaction between the expanded empty p-orbital on the Ga atom and the electron-rich sp2 carbons of the C═C double bond in GaH-5. Moreover, GaH-10 and one of the isomer, nine-membered ring derivative (ClGaC8H8)GaCl, were found to be thermodynamically more stable, as compared to GaH-5.

Reactivity of Silylene with Gallium- and Boron Trihalide at Reductive Conditions Resulting in Unforeseen Products.

Herein, we report a one-pot reaction of gallium and boron halides with potassium graphite in the presence of benzamidinate stabilized silylene LSi-R, (L=PhC(Nt Bu)2 ). The reaction of LSiCl with an equivalent amount of GaI3 in the presence of KC8 leads to the direct substitution of one chloride group by gallium diiodide simultaneously additional coordination of silylene resulted in L(Cl)Si→GaI2 -Si(L)→GaI3 (1). In compound 1, the structure comprises two differently coordinated gallium atoms where one gallium presents between two silylenes and the other gallium is only coordinated by one silylene. In this Lewis acid-base reaction the oxidation states of the starting materials remain unchanged. The same is valid in the silylene boron adduct formation of L(t Bu)Si-BPhCl2 (2) and L(t Bu)Si-BBr3 (3). This new route provides access to galliumhalosilanes challenging to synthesize by any other method.

Codiffusion of Gallium and Phosphorus Atoms in Silicon

Codiffusion of Gallium and Phosphorus Atoms in Silicon

Reduction of vacancy defects induced by thermal annealing in β-Ga2O3 epilayer

The effects of annealing in oxygen atmosphere of β-Ga2O3 epilayers were investigated by X-ray photoelectron spectroscopy, photoluminescence and Fourier-transform infrared spectroscopy. The increasing proportions of Ga3+ and OL (lattice oxygen) signifies the reduction of VO as the annealing temperature rising. The variations of the photoluminescence emissions demonstrate the improvement of the crystal quality and reduction of VO(1), VO(2) and VGa. VO and VGa are filled with oxygen atoms and gallium atoms after annealing, mainly attributed to the bonds constructions of Ga (1)–O (1) and Ga (1)–O (2) in GaO4 tetrahedra. These results offer detailed information and guidelines for removing intrinsic point defects in β-Ga2O3.

Thick-walled coating in Gunn diode for measuring of electromagnetic radiation power in microwave range

In the introduction, the analysis of the physical basis for the operation of the semiconductor Gunn diode is carried out and the issues that should be resolved in substantiation of the basic physical principles of this diode operation are stated. At applied voltages of up to 0.6 V to a gallium arsenide or indium phosphide Gunn diode, free electrons appear in the conduction band of aluminum as a result of ionization of negative ions of gallium or indium atoms. At voltages from 0.6 to 2.0 V, free electrons appear in the aluminum conduction band as a result of ionization of negative ions of arsenic atoms, and at voltages from 0.6 to 3.0 V — phosphorus. The formation of negative gallium or indium ions is caused by electron capture directly from the aluminum base, while the formation of negative arsenic or phosphorus ions is mainly due to spontaneous electron transfer from the aluminum conduction band and from the negative gallium or indium ions. Electric current flows only over the surface of a gallium arsenide or indium phosphide crystal. The frequency of electric current oscillation is defined by the voltage applied to the Gunn diode and the thickness of the gallium arsenide or indium phosphide crystal. Determination of the power of microwave signals by the Gunn diode is carried out by applying a constant voltage between the cathode and the anode, which provides the frequency of current oscillation equal to the frequency of the measured microwave signal. The maximum radiation power in microwave wavelengths measured by the Gunn diode is determined by the equality of the electromagnetic wave perturbation energy and the electron affinity energy of gallium or indium atoms in the vicinity of the aluminum conduction band.

A DFT study on effective detection of ClCN gas by functionalized, decorated, and doped nanocone strategies.

Density Functional Theory (DFT) was employed to investigate the interaction between cyanogen chloride (ClCN) and the surface of a carbon nanocone (CNC). The findings of this research revealed that pristine CNC is not an ideal material to detect ClCN gas due to its minimal alterations in electronic properties. In order to enhance the properties of carbon nanocones, multiple methods were implemented. These included functionalizing the nanocones with pyridinol (Pyr) and pyridinol oxide (PyrO) as well as decorating them with metals such as boron (B), aluminium (Al) and gallium (Ga). Additionally, the nanocones were also doped with the same third-group metal (B, Al and Ga). The simulation results indicated that doping it with aluminium and gallium atoms yielded promising results. After a comprehensive optimization process, two stable configurations were obtained between the ClCN gas and the CNC-Al, and CNC-Ga structures (configurations S21, and S22) with E ads values of -29.11, and -23.70 kcal mol-1 respectively, using M06-2X/6-311G(d) level. The adsorption of ClCN on CNC-Al and CNC-Ga surfaces leads to a marked alteration in the electrical properties of these structures. Calculations reveal that the energy gap between the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) levels (E g) of these configurations increased in the range of 9.03% and 12.54%, respectively, thereby giving off a chemical signal. An analysis conducted by the NCI confirms that there is a strong interaction between ClCN and Al and Ga atoms in CNC-Al and CNC-Ga structures, which is represented by the red color in the RDG isosurfaces. Additionally, the NBO charge analysis reveals that significant charge transfer is present in S21 and S22 configurations (190 and 191 |me|, respectively). These findings suggest that the adsorption of ClCN on these surfaces impacts the electron-hole interaction, which subsequently alters the electrical properties of the structures. Based on the DFT results, the CNC-Al and CNC-Ga structures, which have been doped with aluminium and gallium atoms, respectively, have the potential to serve as good candidates for detecting ClCN gas. Among these two structures, the CNC-Ga structure emerged as the most desirable one for this purpose.

Effective electronic band structure of monoclinic β−(AlxGa1−x)2O3 alloy semiconductor

In this article, the electronic band structure of a β−(AlxGa1−x)2O3 alloy system is calculated, with β−Ga2O3 as the bulk crystal. The technique of band unfolding is implemented to obtain an effective band structure for aluminum fractions varying between 12.5% and 62.5% with respect to gallium atoms. A 160-atom supercell is used to model the disordered system that is generated using the technique of special quasi-random structures, which mimics the site correlation of a truly random alloy by reducing the number of candidate structures that arise due to the large number of permutations possible for alloy occupation sites. The impact of the disorder is then evaluated on the electron effective mass and bandgap, which is calculated under the generalized gradient approximation.

Синтез методом молекулярно-пучковой эпитаксии и свойства InAs-квантовых точек в теле AlGaAs нитевидных нанокристаллов

We present the results of experimental studies on the synthesis by molecular-beam epitaxy of AlGaAs nanowires with InAs quantum dots. The morphological, structural, and optical properties of the grown nanostructures have been studied. It is important to note that the emission from quantum dots is observed in the wavelength range from 750 to 970 nm. Assumptions about the nature of short-wavelength emission from quantum dots are formulated. In particular, one of the reasons may be a significant desorption of indium atoms and the presence of gallium atoms in catalyst drops during the growth at a substrate temperature of 510◦C. The proposed technology opens up new possibilities for integration direct-gap III−V materials with a silicon platform for various applications in photonics and quantum communications.

Особенности структуры поверхности и поверхностного электронного транспорта в коррелированном топологическом изоляторе SmB-=SUP=-VI-=/SUP=-

We present the results of experimental studies on the synthesis by molecular-beam epitaxy of AlGaAs nanowires with InAs quantum dots. The morphological, structural, and optical properties of the grown nanostructures have been studied. It is important to note that the emission from quantum dots is observed in the wavelength range from 750 to 970 nm. Assumptions about the nature of short-wavelength emission from quantum dots are formulated. In particular, one of the reasons may be a significant desorption of indium atoms and the presence of gallium atoms in catalyst drops during the growth at a substrate temperature of 510◦C. The proposed technology opens up new possibilities for integration direct-gap III−V materials with a silicon platform for various applications in photonics and quantum communications.

GaP-=SUB=-x-=/SUB=-As-=SUB=-1-x-=/SUB=- solid solution growth by molecular beam epitaxy: phenomenological description of the x dependence from growth conditions on GaAs(001) substrate

The experimental dependences of the GaPxAs1-x solid solution phosphorus proportion on growth conditions by molecular beam epitaxy from As2 and P2 molecules on GaAs(001) substrate were described using the phenomenological model. The model was built on the well-established ideas about the III-V compounds MBE growth. The ratio of the arsenic and phosphorus atoms incorporation coefficients was considered as a function of the substrate temperature and molecular flux densitys. Empirical expressions were found that describe the behavior of the arsenic and phosphorus incorporation coefficients ratio depending on the indicated growth parameters. This makes it possible to estimate the V group molecule flux values to obtain the required x in a GaPxAs1-x solid solution at the given substrate temperature and the gallium atoms flow density. Keywords: molecular beam epitaxy, AIIIBV, solid solutions, GaPxAs1-x, phenomenological model.

Молекулярно-лучевая эпитаксия твердого раствора GaP-=SUB=-x-=/SUB=-As-=SUB=-1-x-=/SUB=-: феноменологическое описание зависимости x от условий роста на подложке GaAs(001)

The experimental dependences of the GaPx As1−x solid solution phosphorus proportion on growth conditions by molecular beam epitaxy from As2 and P2 molecules on GaAs(001) substrate were described using the phenomenological model. The model was built on the well-established ideas about the III−V compounds MBE growth. The ratio of the arsenic and phosphorus atoms incorporation coefficients was considered as a function of the substrate temperature and molecular flux densitys. Empirical expressions were found that describe the behavior of the arsenic and phosphorus incorporation coefficients ratio depending on the indicated growth parameters. This makes it possible to estimate the V group molecule flux values to obtain the required x in a GaPx As1−x solid solution at the given substrate temperature and the gallium atoms flow density.

Molecular dynamics study of tensile properties of graphene/GaN heterostructures

Graphene/GaN nanocomposites have been widely used in high-power and high-frequency optoelectronic devices. At present, the thermal transport characteristics of graphene/gallium nitride heterostructures have been investigated by many scholars, but their mechanical properties have not been systematically studied. In this paper, the effects of graphene layer number, temperature and interfacial structure on the mechanical properties of graphene/GaN heterostructures were investigated by molecular dynamics method. The mechanical properties of materials were analyzed by failure stress, failure strain and Young’s modulus. The simulation results show that the heterogeneous structure is very sensitive to temperature. When the temperature is set at 2000K, the Young’s modulus of the heterostructure decreases by 25.11% compared with that at 300K, which indicates that the increase of temperature will reduce the mechanical properties of graphene composites, However, when the number of graphene layers increases, the mechanical properties of the heterostructures also improved. With the number of graphene layers is set from 1 layer to 5 layers, the performance of the heterostructure is improved, and its Young’s modulus increases by 48.46%. In addition, the effect of interface structure on the young’s modulus of the heterostructure structure is not obvious, but it will affect the maximum failure stress and maximum failure strain of the material. The mechanical properties of graphene in cross section contact with gallium atom are better than those of nitrogen atom. It is beneficial to improve the reliability of microelectronic devices to control and design heterogeneous structures based on the research results.

Non-collinear magnetic structure of the MAX phase Mn2GaC epitaxial films inferred from zero-field NMR study (CE-5:L05)

Zero-field NMR investigations on the 69Ga, 71Ga, and 55Mn nuclei have been performed at 4.2 K on a 100 nm thick epitaxial Mn2GaC(0001) MAX phase film grown on a MgO(111) substrate. This nano-laminated structure consists of ferromagnetic Mn–C–Mn stacks interleaved with monolayers of gallium. A resolved quadrupolar structure of the observed gallium resonances is a fingerprint of a well-defined crystal field confirming high crystal quality. The nuclei of non-magnetic gallium atoms are shown to experience the transferred hyperfine magnetic field of 15.75 T (±0.05 T), which is due to polarization of their 4s electron shell by the magnetic moments of manganese neighbors, evidencing the presence of an uncompensated ferromagnetic moment within the manganese sublattice. The average magnetic moment of manganese was found to be around 2 μB, strongly contrasting with the reported remnant magnetization of only 0.3 μB. Moreover, the 55Mn NMR spectrum indicates the presence of magnetically non-equivalent manganese sites within this structure. The observed features of the 69,71Ga and 55Mn NMR spectra cannot be reconciled with any of the hitherto proposed collinear arrangements of manganese moments and suggest their non-collinear arrangement across a gallium layer. Nevertheless a more advanced study is required to elucidate the detailed nature of magnetic structure in this material.

Heteroepitaxial Growth of Vertically-Aligned GaN Single-Crystalline Microrod Arrays on Silicon Substrates.

The heteroepitaxial growth of vertically aligned gallium nitride (GaN) single-crystalline microrod arrays on silicon substrates was achieved with high reproducibility by using the plasma-enhanced chemical vapor deposition (PECVD) method in the furnace. By reducing the plasma power from 70 to 15 W, the crystal morphology of GaN varied from thin films to microrod arrays with the decreased V/III gas ratio. The growth of GaN crystals occurred in the vertical direction of the substrate and in the lateral direction of the growth axis via the self-catalytic vapor-liquid-solid mechanism (VLS mechanism) and the vapor-solid mechanism (VS mechanism), respectively, contributing to the formation of inverted hexagonal GaN cone microrods. Furthermore, the morphology of inverted hexagonal GaN cone microrods shows extremely small contact areas between the microrods and the substrate, suggesting the potential to solve the problems of stress accumulation and poor crystalline qualities of heteroepitaxy. With the raised growth temperature of GaN from 930 to 980 °C, the material quality was improved and the high crystalline qualities were obtained, owing to the successful surface migration of gallium atoms. However, the density of GaN microrods became lower with the increased growth temperature because the spatial temperature gradient was reduced and the evaporation of gallium was enhanced, leading to fewer gallium atoms precipitating and remaining on the substrate. The growth direction of vertically aligned GaN single-crystalline microrod arrays with the (002) crystal plane is along the [0001] orientation (c axis) and normal to the substrate surface, which may bring about many device applications in future studies.

All Solution-Processed Inorganic, Multilevel Memristors Utilizing Liquid Metals Electrodes Suitable for Analog Computing.

Herein, we report a solution-processable memristive device based on bismuth vanadate (BiVO4) and titanium dioxide (TiO2) with gallium-based eutectic gallium-indium (EGaIn) and gallium-indium-tin alloy (GaInSn) liquid metal as the top electrode. Scanning electron microscopy (SEM) shows the formation of a nonporous structure of BiVO4 and TiO2 for efficient resistive switching. Additionally, the gallium-based liquid metal (GLM)-contacted memristors exhibit stable memristor behavior over a wide temperature range from -10 to +90 °C. Gallium atoms in the liquid metal play an important role in the conductive filament formation as well as the device's operation stability as elucidated by I-V characteristics. The synaptic behavior of the GLM-memristors was characterized, with excellent long-term potentiation (LTP) and long-term depression (LTD) linearity. Using the performance of our device in a multilayer perceptron (MLP) network, a ∼90% accuracy in the handwriting recognition of modified national institute of standards and technology database (MNIST) was achieved. Our findings pave a path for solution-processed/GLM-based memristors which can be used in neuromorphic applications on flexible substrates in a harsh environment.

Mg2MnGa3 – An orthorhombically distorted superstructure variant of the hexagonal Laves phase MgZn2

Abstract The Laves phase Mg2MnGa3 was synthesized from the elements by arc-melting and subsequent annealing in a silica ampoule at T = 670 K. The structure of Mg2MnGa3 was refined from single-crystal X-ray diffractometer data: URe2 type, Cmcm, a = 543.24(1), b = 869.59(3), c = 858.58(2) pm, wR2 = 0.0556, 273 F 2 values and 24 variables. The manganese and gallium atoms form a three-dimensional network of corner- and face-sharing MnGa3 tetrahedra that derive as a ternary ordering variant from the hexagonal Laves phase MgZn2. The structures of the distortion and coloring variants, i.e., MgZn2, URe2, Mg2Cu3Si and Mg2MnGa3 are discussed on the basis of a Bärnighausen tree. The electronic structure calculation data indicate that in addition to the metallic type of bonding an additional covalent interaction appears between the Ga–Ga and Mn–Ga atoms.

Tetra-carbonyldi-μ-chlorido-di-chlorido-bis-(η5-cyclo-penta-dien-yl)diirondigallium(2 Fe-Ga).

The title compound, [Fe2Ga2(C5H5)2Cl4(CO)4], has an iron-gallium bond distance of 2.3028 (3) Å. The gallium atoms are connected by two bridging chlorine atoms, each gallium also has one terminal chlorine. The mol-ecule has an inversion center located between the gallium atoms. The cyclo-penta-dienyl ligand is disordered over two sites with an occupancy of 0.57 (2) for the major occupied site.

Understanding indium incorporation of InGaN grown on polar, semi-polar, and non-polar orientation by metal–organic vapor phase epitaxy

We studied indium incorporation into InGaN/GaN quantum wells grown by metal–organic vapor phase epitaxy by systematically varying of gallium and indium precursor flows on (0001), (101¯3), (112¯2), and (101¯0) orientations. The layer thickness and indium composition obtained from x-ray diffraction analysis were correlated with a model based on indium and gallium incorporation efficiencies. In the model, the indium incorporation efficiency is reproduced by the Langmuir surface coverage of gallium, indicating that indium atoms close to gallium atoms can be incorporated preferably.

Saturable absorption and reverse saturable absorption of CdGa2Se4 nanoparticles determined by bond strength

The nonlinear optical (NLO) properties of selenide gallium-cadmium (CdGa2Se4) nanoparticles (NPs) are investigated by femtosecond open-aperture Z-scan technique. The results show that they exhibit saturable absorption at 400 nm while reverse saturable absorption at 800 nm, which is ascribed to single-photon absorption and two-photon absorption, respectively. The NLO response conversion can be attributed to its band gap determined by the moderate bond strength of gallium and selenium atoms. An empirical equation for band gap and proton number of CdGa2Se4's belonging class of compounds is proposed. It can be used to estimate the band gap values of this class of compounds and predict their nonlinear optical responses at different waveband.

Joint Diffusion of Gallium and Phosphorus Atoms in Silicon

It was found that the diffusion of gallium and phosphorus atoms from the gas phase into silicon not only compensates, but also a particular interaction with each other. Elemental analysis on a scanning electron microscope showed that gallium and phosphorus atoms are present on the silicon surface after diffusion and processing in similar concentrations. Investigation of the concentration distribution of charge carriers over depth shows that, upon joint diffusion, the solubility of gallium increases by one order of magnitude. In this case, the mobility of charge carriers decreased 3–4 times. Based on the data obtained, the concentration (~ 1019 cm-3) of neutral complexes [Ga-P+] and their formation energy (~ 0.62 eV) were calculated. The results obtained can be associated with the electrostatic interaction of gallium and phosphorus ions during diffusion, as a result of which, the concentration distribution of impurities changes, as well as the formation of quasineutral complexes of the [Ga-P+] type in the silicon lattice.