Use of ring-expanded diamino- and diamidocarbene ligands in copper catalyzed azide-alkyne "click" reactions

The two-coordinate ring-expanded N-heterocyclic carbene copper­(I) complexes [Cu­(RE-NHC)₂]⁺ (RE-NHC = 6-Mes, 7-<i>o</i>-Tol, 7-Mes) have been prepared and shown to be effective catalysts under neat conditions for the 1,3-dipolar cycloaddition of alkynes and azides. In contrast, the cationic diamidocarbene analogue [Cu­(6-MesDAC)₂]⁺ and the neutral species [(6-MesDAC)­CuCl]₂ and [(6-MesDAC)₂(CuCl)₃] show good activity when the catalysis is performed on water

Atomic layer deposited beryllium oxide: Effective passivation layer for III-V metal/oxide/semiconductor devices

Electrical and physical characteristics of the atomic layer deposited beryllium oxide (BeO) grown on the Si and GaAs substrates were evaluated as a barrier/passivation layer in the III-V devices. Compared to Al2O3, BeO exhibits lower interface defect density and hysteresis, and smaller frequency dispersion and leakage current density at the same effective oxide thickness, as well as an excellent self-cleaning effect. These dielectric characteristics combined with its advantageous intrinsic properties, such as high thermal stability, large energy band-gap(10.6 eV), effective diffusion barrier, and low intrinsic structural defects, make BeO an excellent candidate for the interfacial passivation layer applications in the channel III-V devices

Tuning the Electronic Properties of Carbenes: A Systematic Comparison of Neighboring Amino versus Amido Groups

A related series of six-membered carbenes featuring adjoining amino and/or amido groups (i.e, a diaminocarbene, a monoamido-aminocarbene (3), and a a diamidocarbene (6)) were systematically compared using crystallographic, spectroscopic, electro-chemical, and density functional theory methods. The solid-state structure of 3 was found to exhibit inequivalent nitrogen carbon bond lengths (C-carbene-N-amide= 1.395(4) angstrom vs C-carbene-N-amine = 1.323(4) angstrom). Moreover, the C-carbene-N-amide distance was longer than that measured in the solid-state structure of 6 (1.371(3) angstrom), while the C-carbene-N-amine distance was similar to that measured in the solid-state structure of a cyclic alkyl-aminocarbene (1.315(3) angstrom). Iridium complexes of the aforementioned carbenes were also evaluated, and the collected data revealed that the introduction of carbonyl groups to the carbene-containing scaffold had a nearly linear, additive effect on the E-1/2 potential of the carbene-ligated iridium I/II redox couple (+165 mV per carbonyl added) as well as the Tolman electronic parameter value of the corresponding carbene-Ir(CO)(2)Cl complex (ca. 7 cm(-1) per carbonyl added). Beyond attenuated ligand donicity, the introduction of carbonyl groups was found to broaden the chemical reactivity: unlike prototypical N-heterocyclic carbenes, including diaminocarbenes, the monoamido-aminocarbene was found to couple to isonitriles to form the respective ketenimines

L-g=100 nm In0.7Ga0.3As quantum well metal-oxide semiconductor field-effect transistors with atomic layer deposited beryllium oxide as interfacial layer

In this study, we have fabricated nanometer-scale channel length quantum-well (QW) metal-oxide-semiconductor field effect transistors (MOSFETs) incorporating beryllium oxide (BeO) as an interfacial layer. BeO has high thermal stability, excellent electrical insulating characteristics, and a large band-gap, which make it an attractive candidate for use as a gate dielectric in making MOSFETs. BeO can also act as a good diffusion barrier to oxygen owing to its small atomic bonding length. In this work, we have fabricated In0.53Ga0.47As MOS capacitors with BeO and Al2O3 and compared their electrical characteristics. As interface passivation layer, BeO/HfO2 bilayer gate stack presented effective oxide thickness less 1 nm. Furthermore, we have demonstrated In0.7Ga0.3As QW MOSFETs with a BeO/HfO2 dielectric, showing a sub-threshold slope of 100 mV/dec, and a transconductance (g(m, max)) of 1.1 mS/mu m, while displaying low values of gate leakage current. These results highlight the potential of atomic layer deposited BeO for use as a gate dielectric or interface passivation layer for III-V MOSFETs at the 7 nm technology node and/or beyond. (C) 2014 AIP Publishing LLC

Inversion type InP metal oxide semiconductor field effect transistor using novel atomic layer deposited BeO gate dielectric

We present results on n-channel inversion-type indium phosphide (InP) metal-oxide-semiconductor field-effect transistors (MOSFETs) with atomic layer deposited (ALD) beryllium oxide (BeO) gate dielectric using the gate-last process. InP MOSFETs with the BeO gate stack were realized with high performance including the improved drive current, subthreshold swing, and a peak effective electron mobility. The transmission electron microscopy and x-ray photoemission spectroscopy measurements demonstrate an interface between BeO and InP substrates with high quality and efficient thermal stability. The use of ALD BeO as a gate dielectric may be a potential solution for future III-V MOS device fabrication

Electrical and physical characteristics for crystalline atomic layer deposited beryllium oxide thin film on Si and GaAs substrates

In a previous study, atomic layer deposited (ALD) BeO exhibited less interface defect density and hysteresis, as well as less frequency dispersion and leakage current density, at the same equivalent oxide thickness than Al2O3. Furthermore, its self-cleaning effect was better. In this study, the physical and electrical characteristics of ALD BeO grown on Si and GaAs substrates are further evaluated as a gate dielectric layer in III-V metal-oxide-semiconductor devices using transmission electron microscopy, selective area electron diffraction, second harmonic generation, and electrical analysis. An as-grown ALD BeO thin film was revealed as a layered single crystal structure, unlike the well-known ALD dielectrics that exhibit either poly-crystalline or amorphous structures. Low defect density in highly ordered ALD BeO film, less variability in electrical characteristics, and great stability under electrical stress were demonstrated

A study of highly crystalline novel beryllium oxide film using atomic layer deposition

Beryllium oxide (BeO), which has excellent electrical insulating characteristics and high thermal stability, is a promising gate dielectric and interface passivation layer (IPL), because of its high energy bandgap (10.6 eV) and short bond distance between Be and 0 atoms. In a previous study, we demonstrated the excellent electrical and physical characteristics of BeO grown after atomic layer deposition (ALD) on Si and GaAs substrates. Here we report, for the first time, ALD growth of crystalline BeO as a potential high-k gate dielectric and IPL. From TEM, SAD, RHEED, and XRD, we have found that highly crystalline BeO thin film may be grown in a wurtzite structure as a (101) plane on a Si (100) oriented surface. We have also investigated a germanium epitaxial layer grown on BeO as a semiconductor-on-insulator (SOI) application, and the crystallinity of BeO on a GaAs (100) substrate for III-V MOS device applications