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1. Threshold Ion Energies and Cleaning of Etch Residues During Inductively Coupled Etching of NiO/Ga ₂ O ₃ in BCl ₃

   https://doi.org/10.1149/2162-8777/ac9ff3  

   Chiang, Chao-Ching; Xia, Xinyi; Li, Jian-Sian; Ren, Fan; Pearton, S. J. (November 2022, ECS Journal of Solid State Science and Technology)

   BCl 3 is an attractive plasma etchant for oxides because it is a Lewis acid used to scavenge native oxides on many semiconductors due to the strong B–O bonding. We investigated BCl 3 -based dry etching of the NiO/Ga 2 O 3 heterojunction system. BCl 3 /Ar Inductively Coupled Plasmas produced maximum etch rates for NiO up to 300 Å.min −1 and 800 Å.min −1 for β -Ga 2 O 3 under moderate plasma power conditions suitable for low damage pattern transfer. The selectivity for NiO: Ga 2 O 3 was <1 under all conditions. The ion energy threshold for initiation of etching of NiO was between 35–60 eV, depending on the condition and the etch mechanism was ion-driven, as determined by the linear dependence of etch rate on the square root of ion energy incident on the surface. By sharp contrast, the etching of Ga 2 O 3 had a stronger chemical component, without a well-defined ion energy threshold. The as-etched NiO and Ga 2 O 3 surfaces show chlorine residues, which can be removed on both materials by the standard 1NH 4 OH: 10H 2 O or 1HCl: 10H 2 O rinses used for native oxide removal. According to the location of the Cl 2p 3/2 peak, the Cl is ionically bonded. 

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2. Crystallographic characterization of rare-earth cyanotriphenylborate complexes and the cyanoborates [NCBPh ₃ ] ¹⁻ , [NCBPh ₂ Me] ¹⁻ , and [NCBPh ₂ (μ-O)BPh ₂ ] ¹⁻

   https://doi.org/10.1107/S2056989021006861  

   Dumas, Megan T.; White, Jessica R.; Ziller, Joseph W.; Evans, William J. (August 2021, Acta Crystallographica Section E Crystallographic Communications)

   The investigation of the coordination chemistry of rare-earth metal complexes with cyanide ligands led to the isolation and crystallographic characterization of the Ln III cyanotriphenylborate complexes dichlorido(cyanotriphenylborato-κ N )tetrakis(tetrahydrofuran-κ O )lanthanide(III), [ Ln Cl 2 (C 19 H 15 BN)(C 4 H 8 O) 4 ] [lanthanide ( Ln ) = dysprosium (Dy) and yttrium Y)] from reactions of LnCl 3 , KCN, and NaBPh 4 . Attempts to independently synthesize the tetraethylammonium salt of (NCBPh 3 ) − from BPh 3 and [NEt 4 ][CN] in THF yielded crystals of the phenyl-substituted cyclic borate, tetraethylazanium 2,2,4,6-tetraphenyl-1,3,5,2λ 4 ,4,6-trioxatriborinan-2-ide, C 8 H 20 N + ·C 24 H 20 B 3 O 3 − or [NEt 4 ][B 3 (μ-O) 3 (C 6 H 5 ) 4 ]. The mechanochemical reaction of BPh 3 and [NEt 4 ][CN] without solvent produced crystals of tetraethylazanium cyanodiphenyl-λ 4 -boranyl diphenylborinate, C 8 H 20 N + ·C 25 H 20 B 2 NO − or [NEt 4 ][NCBPh 2 (μ-O)BPh 2 ]. Reaction of BPh 3 and KCN in THF in the presence of 2.2.2-cryptand (crypt) led to a crystal of bis[(2.2.2-cryptand)potassium] 2,2,4,6-tetraphenyl-1,3,5,2λ 4 ,4,6-trioxatriborinan-2-ide cyanomethyldiphenylborate tetrahydrofuran disolvate, 2C 18 H 36 KN 2 O 6 + ·C 24 H 20 B 3 O 3 − ·C 14 H 13 BN − ·2C 4 H 8 O or [K(crypt)] 2 [B 3 (μ-O) 3 (C 6 H 5 ) 4 ][NCBPh 2 Me]·2THF. The [NCBPh 2 (μ-O)BPh 2 ] 1− and (NCBPh 2 Me) 1− anions have not been structurally characterized previously. The structure of 1-Y was refined as a two-component twin with occupancy factors 0.513 (1) and 0.487 (1). In 4 , one solvent molecule was disordered and included using multiple components with partial site-occupancy factors. 

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3. Selective Wet and Dry Etching of NiO over β-Ga ₂ O ₃

   https://doi.org/10.1149/2162-8777/ac94a0  

   Chiang, Chao-Ching; Xia, Xinyi; Li, Jian-Sian; Ren, Fan; Pearton, S. J. (October 2022, ECS Journal of Solid State Science and Technology)

   Patterning of NiO/Ga 2 O 3 heterojunctions requires development of selective wet and dry etch processes. Solutions of 1:4 HNO 3 :H 2 O exhibited measurable etch rates for NiO above 40 °C and activation energy for wet etching of 172.9 kJ.mol −1 (41.3 kCal.mol −1 , 1.8 eV atom −1 ), which is firmly in the reaction-limited regime. The selectivity over β -Ga 2 O 3 was infinite for temperatures up to 55 °C. The strong negative enthalpy for producing the etch product Ga(OH) 4 suggests HNO 3 -based wet etching of NiO occurs via formation and dissolution of hydroxides. For dry etching, Cl 2 /Ar Inductively Coupled Plasmas produced etch rates for NiO up to 800 Å.min −1 , with maximum selectivities of <1 over β -Ga 2 O 3 . The ion energy threshold for initiation of etching of NiO was ∼55 eV and the etch mechanism was ion-driven, as determined the linear dependence of etch rate on the square root of ion energy incident on the surface. 

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4. N ₃ -Ligated nickel( ii ) diketonate complexes: synthesis, characterization and evaluation of O ₂ reactivity

   https://doi.org/10.1039/d0dt01338b  

   Elsberg, Josiah G.; Peterson, Austin; Fuller, Amy L.; Berreau, Lisa M. (January 2020, Dalton Transactions)

   Interest in O 2 -dependent aliphatic carbon–carbon (C–C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O 2 -dependent aliphatic C–C bond cleavage at ambient temperature in Ni( ii ) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl ( 7-Cl ; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt 3 spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni( ii ) diketonate complexes of the general formula [(TERPY)Ni(R 2 -1,3-diketonate)]ClO 4 ( 1 : R = CH 3 ; 2 : R = C(CH 3 ) 3 ; 3 : R = Ph) was prepared under air and characterized using single crystal X-ray crystallography, elemental analysis, 1 H NMR, ESI-MS, FTIR, and UV-vis. Analysis of the reaction mixtures in which these complexes were generated using 1 H NMR and ESI-MS revealed the presence of both the desired diketonate complex and the bis-TERPY derivative [(TERPY) 2 Ni](ClO 4 ) 2 ( 4 ). Through selective crystallization 1–3 were isolated in analytically pure form. Analysis of reaction mixtures leading to the formation of the MBBP analogs [(MBBP)Ni(R 2 -1,3-diketonate)]X (X = ClO 4 : 5 : R = CH 3 ; 6 : R = C(CH 3 ) 3 ; 7-ClO4 : R = Ph; X = Cl: 7-Cl : R = Ph) using 1 H NMR and ESI-MS revealed the presence of [(MBBP) 2 Ni](ClO 4 ) 2 ( 8 ). Analysis of aerobic acetonitrile solutions of analytically pure 1–3 , 5 and 6 containing NEt 3 and in some cases H 2 O using 1 H NMR and UV-vis revealed evidence for the formation of additional bis-ligand complexes ( 4 and 8 ) but suggested no oxidative diketonate cleavage reactivity. Analysis of the organic products generated from 3 , 7-ClO4 and 7-Cl revealed unaltered dibenzoylmethane. Our results therefore indicate that N 3 -ligated Ni( ii ) complexes of unsubstituted diketonate ligands do not exhibit O 2 -dependent aliphatic C–C bond clevage at room temperature, including in the presence of NEt 3 and/or H 2 O. 

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5. Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb ₃ AlSb ₃

   https://doi.org/10.1107/S2053229621005192  

   Shang, Rongqing; Nguyen, An T.; He, Allan; Kauzlarich, Susan M. (June 2021, Acta Crystallographica Section C Structural Chemistry)

   null (Ed.)

   A rare-earth-containing compound, ytterbium aluminium antimonide, Yb 3 AlSb 3 (Ca 3 AlAs 3 -type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb 2+ ) 3 [(Al 1− )( 1b – Sb 2− ) 2 ( 2b – Sb 1− )], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb 4 tetrahedra, [AlSb 2 Sb 2/2 ] 6− , with Yb 2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported. 

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