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We investigated the carrier dynamics of ammonothermal Mn-compensated gallium nitride (GaN:Mn) semiconductors by using sub-bandgap and above-bandgap photo-excitation in a photoluminescence analysis and pump–probe measurements. The contactless probing methods elucidated their versatility for the complex analysis of defects in GaN:Mn crystals. The impurities of Mn were found to show photoconductivity and absorption bands starting at the 700 nm wavelength threshold and a broad peak located at 800 nm. Here, we determined the impact of Mn-induced states and Mg acceptors on the relaxation rates of charge carriers in GaN:Mn based on a photoluminescence analysis and pump–probe measurements. The electrons in the conduction band tails were found to be responsible for both the photoconductivity and yellow luminescence decays. The slower red luminescence and pump–probe decays were dominated by Mg acceptors. After photo-excitation, the electrons and holes were quickly thermalized to the conduction band tails and Mg acceptors, respectively. The yellow photoluminescence decays exhibited a 1 ns decay time at low laser excitations, whereas, at the highest ones, it increased up to 7 ns due to the saturation of the nonradiative defects, resembling the photoconductivity lifetime dependence. The fast photo-carrier decay time observed in ammonothermal GaN:Mn is of critical importance in high-frequency and high-voltage device applications. [ABSTRACT FROM AUTHOR]

Abstract Environmental issues and the global need to increase economically sustainable access to electricity addressed and boosted scientific research and use of Distributed Energy Resources, such as solar Photovoltaic (PV). Multi‐port power converters can be of great interest for a compact and efficient interface between PV, storage units, and DC loads. The Triple Active Bridge (TAB) shows interesting advantages in terms of isolation and Zero Voltage Switching capabilities over wide load and input voltage ranges. This work aims to develop a TAB prototype for a NanoGrid (NG) application, analyzing the possibility of a direct interface of PV modules, storage units, and DC loads, without the use of intermediate conversion stages. The TAB prototype uses Gallium Nitride devices, and an evaluation of the overall efficiency is provided, useful to compare with other isolated three‐port converters. Through an analytical approach, a TAB has been sized and optimized to meet specific application requirements. MATLAB/Simulink simulations have been done for the sizing validation and the control strategy design. A prototype has been developed and experimental measurements have been compared with simulation results. The TAB is proposed as a key element of DC NGs, but applications of interest are also automotive, More Electric Aircraft, and naval applications.

Environmental issues and the global need to increase economically sustainable access to electricity addressed and boosted scientific research and use of Distributed Energy Resources, such as solar Photovoltaic (PV). Multi‐port power converters can be of great interest for a compact and efficient interface between PV, storage units, and DC loads. The Triple Active Bridge (TAB) shows interesting advantages in terms of isolation and Zero Voltage Switching capabilities over wide load and input voltage ranges. This work aims to develop a TAB prototype for a NanoGrid (NG) application, analyzing the possibility of a direct interface of PV modules, storage units, and DC loads, without the use of intermediate conversion stages. The TAB prototype uses Gallium Nitride devices, and an evaluation of the overall efficiency is provided, useful to compare with other isolated three‐port converters. Through an analytical approach, a TAB has been sized and optimized to meet specific application requirements. MATLAB/Simulink simulations have been done for the sizing validation and the control strategy design. A prototype has been developed and experimental measurements have been compared with simulation results. The TAB is proposed as a key element of DC NGs, but applications of interest are also automotive, More Electric Aircraft, and naval applications. [ABSTRACT FROM AUTHOR]

The discovery of mechanically soft solid‐state materials with fast Mg‐ion conduction is crucial for the development of solid‐state magnesium batteries. In this paper, novel magnesium gallium halide compounds are reported that achieve high ionic conductivity of 0.47 mS cm−1 at room temperature. These Mg‐ion conductors obtained by ball milling Mg and Ga salts exhibit clay‐like mechanical properties, enabling intimate contact at the electrode–electrolyte interface during battery cycling. With a combination of experimental and computational analysis, this study identifies that the soft‐clay formation is induced by partial anion exchange during milling. This partial anion exchange creates undercoordinated magnesium ions in a chlorine‐rich environment, yielding fast Mg‐ion conduction. This work demonstrates the potential of clay‐like halide electrolytes for all‐solid‐state magnesium batteries, with possible further extension to other multivalent battery systems. [ABSTRACT FROM AUTHOR]

Herein, the first F-containing iodate-phosphate, namely Ba2Ga2F6(IO3)(PO4), was prepared via a hydrothermal reaction, in which HPF6 (70 wt% solution in water) was used as the source of both fluoride and phosphate anions for the first time. Ba2Ga2F6(IO3)(PO4) features an unprecedented 1D [Ga2F6(IO3)(PO4)]4− helix chain, composed of a 1D Ga(1)(IO3)O4F chain via the bridging of 0D Ga(2)(PO4)F5. The UV-Vis spectrum shows that Ba2Ga2F6(IO3)(PO4) has a wide bandgap with a short-UV absorption edge (4.35 eV; 253 nm). Birefringence measurement under a polarizing microscope shows that Ba2Ga2F6(IO3)(PO4) displays a moderate birefringence of 0.072@550 nm, which is consistent with the value (0.070@550 nm) obtained by DFT calculations, indicating that Ba2Ga2F6(IO3)(PO4) has potential applications as a short-UV birefringent material. This study highlights the crucial role played by the incorporation of specific functional groups into compounds, shedding light on their contribution to promising inorganic functional materials. [ABSTRACT FROM AUTHOR]

This study explored the inhibitory potential of gallium maltolate against severe acute respiratory syndrome coronavirus 2 and main and papain-like proteases. Computational methods, including density functional theory and molecular docking, were used to assess gallium maltolate reactivity and binding interactions. Density functional theory calculations revealed gallium maltolate's high electron-capturing capacity, particularly around the gallium metal atom, which may contribute to their activity. Molecular docking demonstrated that gallium maltolate can form strong hydrogen bonds with key amino acid residues like glutamate-166 and cysteine-145, tightly binding to main and papain-like proteases. The binding energy and interactions of gallium maltolate were comparable to known SARS-CoV-2 inhibitors like N-[(5-methyl-1,2-oxazol-3-yl)carbonyl]-L-alanyl-L-valyl-N-{(2S,3E)-5-(benzyloxy)-5-oxo-1-[(3S)-2-oxopyrrolidin-3-yl]pent-3-en-2-yl}-L-leucinamide, indicating its potential as an antiviral agent. However, further experimental validation is required to confirm its effectiveness in inhibiting SARS-CoV-2 replication and treating COVID-19. [ABSTRACT FROM AUTHOR]

Lewis superacids (LSA) are defined by a fluoride ion affinity (FIA) that exceeds that of SbF5, and are thus characterized as hard according to the HSAB concept. Soft superacidity was defined for compounds exceeding the hydride ion affinity (HIA) of B(C6F5)3. Herein we report on the synthesis of a Lewis acid being superacidic only on the soft regime: tris(pentafluoroethyl)indane, In(C2F5)3. It is accessible in the form of its dihydrate [In(C2F5)3(OH2)2]. An improved synthesis for the gallium analogue [Ga(C2F5)3(OH2)2] is also reported. Tris(pentafluoroethyl)indane dihydrate, [In(C2F5)3(OH2)2], was fully characterized by IR and NMR spectroscopy, as well as by single crystal X‐ray diffraction. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and ‐indium compounds, for example hydroxogallates and ‐indates. An attempt to determine its gas‐phase structure and that of the gallium analogue by electron diffraction demonstrates that they lose water ligands upon evaporation. The energetics of these processes were predicted by quantum‐chemical calculations as was the nature of bonding in the free Lewis acids and their mono‐ and dihydrates. Furthermore, the synthesis and structural diversity of hydroxido tris(pentafluoroethyl) gallates and one indate are presented. [ABSTRACT FROM AUTHOR]

We recently reported the potential of a new gallium compound, gallium acetylacetonate (GaAcAc) in combating osteoclastic bone resorption through inhibition of osteoclast differentiation and function. Herein, we focused on 3D-printed polylactic acid scaffolds that were loaded with GaAcAc and investigated the impact of scaffold pretreatment with polydopamine (PDA) or sodium hydroxide (NaOH). We observed a remarkable increase in scaffold hydrophilicity with PDA or NaOH pretreatment while biocompatibility and in vitro degradation were not affected. NaOH-pretreated scaffolds showed the highest amount of GaAcAc loading when compared to other scaffolds (p < 0.05). NaOH-pretreated scaffolds with GaAcAc loading showed effective reduction of osteoclast counts and size. The trend was supported by suppression of key osteoclast differentiation markers such as NFAT2, c-Fos, TRAF6, & TRAP. All GaAcAc-loaded scaffolds, regardless of surface pretreatment, were effective in inhibiting osteoclast function as evidenced by reduction in the number of resorptive pits in bovine cortical bone slices (p < 0.01). The suppression of osteoclast function according to the type of scaffold followed the ranking: GaAcAc loading without surface pretreatment > GaAcAc loading with NaOH pretreatment > GaAcAc loading with PDA pretreatment. Additional studies will be needed to fully elucidate the impact of surface pretreatment on the efficacy and safety of GaAcAc-loaded 3D-printed scaffolds. [ABSTRACT FROM AUTHOR]

Abstract The authors report a novel structure to improve the high‐frequency performance of nitrogen‐polar GaN deep‐recess high electron mobility transistors (HEMTs) wherein a timed plasma etch was used to tailor the profile of the gate dielectric. A favourable trade‐off between gate fringing capacitance and transconductance was established, resulting in an improved current gain cutoff frequency times gate length (ft·LG) figure of merit compared to standard Schottky‐gate and metal‐insulator‐semiconductor (MIS) HEMTs. The etched gate dielectric MISHEMT demonstrated a maximum ft·LG of 15.0 GHz·µm for an LG of 100 nm.

The authors report a novel structure to improve the high‐frequency performance of nitrogen‐polar GaN deep‐recess high electron mobility transistors (HEMTs) wherein a timed plasma etch was used to tailor the profile of the gate dielectric. A favourable trade‐off between gate fringing capacitance and transconductance was established, resulting in an improved current gain cutoff frequency times gate length (ft·LG) figure of merit compared to standard Schottky‐gate and metal‐insulator‐semiconductor (MIS) HEMTs. The etched gate dielectric MISHEMT demonstrated a maximum ft·LG of 15.0 GHz·µm for an LG of 100 nm. [ABSTRACT FROM AUTHOR]

The interface and bulk properties of ∼20 nm hafnium-silicon-oxide (HfSiOx) dielectric deposited by atomic layer deposition (ALD) on (001) β-Ga2O3 were investigated systematically using deep ultraviolet photo-assisted capacitance–voltage (C–V) and current–voltage (I–V) measurements. The ALD HfSiOx dielectric constant, bulk, and HfSiOx/Ga2O3 interface quality and breakdown field were determined, and the impact of post-deposition annealing (PDA) on these parameters was studied. PDA reduced near-interface traps resulting in a smaller hysteresis without changing the dielectric constant. An average trap density of 2.72 × 1012 and 1.06 × 1012 cm−2 eV−1 was measured on samples with PDA at 400 and 900 °C, respectively. In addition, a high dielectric constant of 9.28 and breakdown field as high as 8.7 MV/cm were achieved on these devices. [ABSTRACT FROM AUTHOR]

Professor Joseph "Joe" Greene taught me a great deal about research, leadership, and how to succeed. He was a mentor and a tireless advocate for me over the course of my career. This article summarizes some of the work that my research group carried out, inspired by Prof. Greene but not in direct collaboration with him. Three examples of these efforts are provided, epitaxial growth of Cu(In,Ga)Se2 (CIGS) on GaAs by sputter deposition, synthesis of Cu-Mo metastable alloys by sputter deposition, and recrystallization of CIGS deposited at high rates by treatment with metal halides. These works were carried out with many collaborators who are acknowledged in the description of the research carried out by them and in the references where full details can be found. [ABSTRACT FROM AUTHOR]

The introduction of a number of unsaturated fluorinated and chlorinated substituents onto gallium and indium was investigated. Gallate, [GaR4]−, and indate, [InR4]−, anions with trifluorovinyl (CF=CF2), 1‐chloro‐2,2‐difluorovinyl (CCl=CF2), (E)‐pentafluoropropen‐1‐yl (E‐CF=CFCF3), 3,3,3‐trifluoropropynyl (C≡C−CF3) and dichloromethyl (CHCl2) substituents were synthesized and isolated as the respective tetraphenylphosphonium salts. The respective gallate and indate salts were characterized by various methods, including NMR spectroscopy, mass spectrometry and X‐ray diffraction analysis. The generation of the respective organyllithium reagents, required for the syntheses of the gallate and indates, was performed starting from commercially available materials. This series of novel gallate and indate salts extends the chemistry of electron withdrawing groups to gallium and indium compounds. [ABSTRACT FROM AUTHOR]

The structure of µ-oxobis(phthalocyaninato)gallium(III) (PcGaOGaPc) and the structure of a second modification of chloro(phthalocyaninato)gallium(III) (ClGaPc) has been determined by single-crystal X-ray analysis. Sublimation of the respective compounds led to single crystals suitable for an X-ray study. Both compounds crystallize in the triclinic space group P 1 ¯ , with a unit cell for ClGaPc a = 13.770 Å, b = 13.770 Å, c = 14.039 Å, α = 98.32°, β = 108.64°, γ = 90.01°, containing four disordered molecules (Z = 4). The unit cell of the dimeric PcGaOGaPc contains one molecule, with half a molecule as an asymmetric moiety (Z = 2) and a = 7.848 Å, b = 12.529 Å, c = 12.720 Å, α = 91.03°, β = 94.94°, γ = 89.98°. The Ga atoms for the two ClGaPc molecules are placed 0.44 Å above the plane formed by the respective isoindole nitrogen N1 to N4. The two rings of the asymmetric unit (molecule 1 and 2) are arranged in parallel, with ca. 3.4 Å distance within the unit cell. The Ga-Cl bond distances are ca. 2.20 Å for the two molecules. The gallium of PcGaOGaPc is placed 0.49 Å above the respective isoindole nitrogen plane and the Ga-O bond amounts to 1.734 Å. [ABSTRACT FROM AUTHOR]

The structure of µ-oxobis(phthalocyaninato)gallium(III) (PcGaOGaPc) and the structure of a second modification of chloro(phthalocyaninato)gallium(III) (ClGaPc) has been determined by single-crystal X-ray analysis. Sublimation of the respective compounds led to single crystals suitable for an X-ray study. Both compounds crystallize in the triclinic space group P1¯, with a unit cell for ClGaPc a = 13.770 Å, b = 13.770 Å, c = 14.039 Å, α = 98.32°, β = 108.64°, γ = 90.01°, containing four disordered molecules (Z = 4). The unit cell of the dimeric PcGaOGaPc contains one molecule, with half a molecule as an asymmetric moiety (Z = 2) and a = 7.848 Å, b = 12.529 Å, c = 12.720 Å, α = 91.03°, β = 94.94°, γ = 89.98°. The Ga atoms for the two ClGaPc molecules are placed 0.44 Å above the plane formed by the respective isoindole nitrogen N1 to N4. The two rings of the asymmetric unit (molecule 1 and 2) are arranged in parallel, with ca. 3.4 Å distance within the unit cell. The Ga-Cl bond distances are ca. 2.20 Å for the two molecules. The gallium of PcGaOGaPc is placed 0.49 Å above the respective isoindole nitrogen plane and the Ga-O bond amounts to 1.734 Å.

• Manganese-doped Sr 2.5 A 0.5 Mn 0.1 M O 4 F produces a range of green hues by substitution of A = Ca, Sr, Ba and M = Al, Ga in the host lattice. • Reduction to anion deficient Sr 2.5 A 0.5 Mn 0.1 M O 4-α F 1-δ phases yields blue colors ranging from pale blue to dark blue-purple (band gaps = 3.31–3.66 eV). • XAS suggests the green colors are due to mixed Mn3+/Mn4+ on the tetrahedral lattice site and blue colors in anion-deficient phases arise from Mn2+ on the 8-coordinate Sr(2) site, consistent with DFT calculations, XAS and PXRD data. A high tunability of green-blue colors in the manganese-doped oxyfluoride Sr 2.5 A 0.5 Mn 0.1 M O 4 F (A = Ca, Sr, Ba; M = Al, Ga) and anion-deficient Sr 2.5 A 0.5 Mn 0.1 M O 4-α F 1-δ (A = Ca, Sr, Ba; M = Al, Ga) is reported, and the chromophore s responsible for this intense pigmentation are investigated. The hues exhibited by these materials are quantified via diffuse reflectance UV/Vis spectroscopy and measurement of their direct band gaps via Tauc plot. It is shown that choice of A cation (A = Ca, Sr, Ba) and M cation (M = Al, Ga) for as-synthesized phases Sr 2.5 A 0.5 Mn 0.1 M O 4 F yield a wide range of green colors (band gap range 2.70–2.96 eV). Treatment of these phases under reducing conditions according to Sr 2.5 A 0.5 Mn 0.1 M O 4-α F 1-δ (A = Ca, Sr, Ba; M = Al, Ga) induces anion non-stoichiometry, shifting the observed colors to a wide range of blue/blue-purple hues (band gaps from 3.31 to 3.66 eV), showing potential as tunable inorganic blue pigments. Density field theory (DFT) calculations support the preferential occupation of the smaller 8-coordinate Sr(2) site by the substituted Mn2+ cation. X-ray absorption near-edge structure (XANES) data reveal more subtle nuances in the interplay between formal manganese oxidation state, crystallographic site and observed hue. In general, for as synthesized (green) Sr 2.5 A 0.5 Mn 0.1 M O 4 F (A = Ca, Sr, Ba; M = Al, Ga), the edge position in Mn K-edge XANES is consistent with mixed Mn3+-Mn4+ oxidation state whilst a clear pre-edge structure suggesting that Mn is present on a tetrahedral site. This would suggest that during the reduction step, Mn3+/Mn4+ is reduced to entirely Mn2+ and migrates from the tetrahedral to the Sr(2) lattice site. [Display omitted] [ABSTRACT FROM AUTHOR]

• A β-Ga 2 O 3 crystal with a diameter of 30 mm was grown by the LDFZ method. • The beam profile was adjusted to heat the molten zone locally and intensively. • Three beam profile patterns were switched with increasing the crystal diameter. • Proper beam profile and proper diameter of the feed rod keep the molten zone stable. To investigate the effect of high-power laser heating on the floating zone (FZ) method, a crystal of β-Ga 2 O 3 was grown by the LDFZ method using a newly developed optical system equipped with a 20-kW laser diode (LD) system as a heat source. The growth started from a twin-free seed crystal with a diameter of 7 mm and the diameter of the crystal was increased gradually up to 30 mm. With increasing the diameter of the crystal, three patterns of the beam intensity profile were switched to heat the whole of the molten zone locally and intensively. The intensity profile of the five beamlets irradiating the sample was adjusted with a combination of the zooming by the optical system and the partial blocking by the alumina cylinder. By the proper tuning of the beam profile and the proper selection of the diameter of the feed rod, the molten zone was kept stable against gravity. The obtained crystal has a layer texture without clear facets or cracks. It almost conserves the crystallographic direction of the seed crystal but is twinned except for a twin-free region near the seed crystal. [ABSTRACT FROM AUTHOR]

Given the problems of easy cleavage and unfavorable surface integrity in the processing of β-Ga 2 O 3 (100), the effects of abrasive type (diamond, silicon carbide, alumina, cerium oxide) and abrasive particle size (W3, W2, W1, W0.5) on substrate processing were investigated via friction and polishing experiments. The results demonstrated that a strong correlation exists between the surface integrity of the β-Ga 2 O 3 (100) substrate and abrasive type, and it was determined that the diamond abrasive with sharp cutting edges was optimal. The abrasive particle size significantly affected the friction wear and polishing effect of β-Ga 2 O 3 (100). The use of fine abrasive particles can effectively inhibit the formation of cleavage pits and scratches. After polishing with the W0.5 diamond, the surface roughness (Ra) of the substrate decreased to 3.8 nm, and the scratch depth decreased to 18 nm. The abrasive particle size significantly affected the friction wear and polishing effect of β-Ga 2 O 3 (100). The shape and size of the abrasive are crucial factors affecting the processing of the β-Ga 2 O 3 (100) substrate. The diamond abrasive particle size distribution was uniform, and the axial ratio of the abrasive was predominantly between 0.6 and 0.9. The surface material of the substrate was removed via the "three-body rolling" method, so the polishing effect was optimal. [Display omitted] • Diamond abrasive can effectively improve the surface integrity of β-Ga 2 O 3 (100) after processing and avoid cleavage fracture of the wafer. • Diamond abrasives with fine particle size can effectively inhibit the formation of cleavage pits and scratches on the surface of β-Ga 2 O 3 (100). • The influence mechanism of the shape and size of abrasives on the motion state of abrasives was analyzed. [ABSTRACT FROM AUTHOR]

Monoclinic gallium oxide (β-Ga 2 O 3) has attracted wide attention due to its low-cost single crystal and excellent optoelectronic properties. However, the low specific surface area and high defect density of β-Ga 2 O 3 thin films result in weak light-matter interaction and poor crystal quality, seriously hindering their applications. In this article, the growth of high light-trapping β-Ga 2 O 3 nanorod (NR) film on GaAs substrates by metal-organic chemical vapor deposition (MOCVD) is demonstrated. The GaAs substrates were pre-treated by thermal oxidation (TO) to produce a β-Ga 2 O 3 seed layer. The effect of MOCVD growth conditions on the morphology of β-Ga 2 O 3 NR films is investigated. The growth mechanism of β-Ga 2 O 3 NR films is studied in detail. X-ray diffraction, Raman, and photoluminescence were employed to study the crystal and optical properties of β-Ga 2 O 3 NR films. A significant light-trapping effect with a 40 % reduction in optical reflectance at the wavelength of 254 nm is observed. The results show that the β-Ga 2 O 3 NR films exhibit strong light-matter interaction and have potential in optoelectronic applications. [ABSTRACT FROM AUTHOR]