Nucleation of Graphene Layers On Magnetic Oxides: Co_3O_4(111) and Cr_2O_3(0001) from Theory and Experiment

We report direct grown strongly adherent graphene on Co_3O_4(111) by Carbon molecular beam epitaxy (MBE) at 850 K and DFT findings that the first graphene layer is reconstructed to fit the Co_3O_4 surface, while subsequent layers retain normal graphene structure. This adherence to the Co_3O_4 structure results from partial bonding of half the carbons to top oxygen of the substrate. This structure is validated by X-ray photoelectron spectroscopy and low energy electron diffraction studies, showing layer-by-layer graphene growth with ~ 0.08 electrons/carbon atom transferred to the oxide from the first graphene layer, in agreement with DFT. In contrast, C MBE on Cr_2O_3(0001) yields only graphite formation at 700 K, with C desorption above 800 K. For Cr_2O_3 DFT finds no strong bonding to the surface, with charge transfer is away from the oxide. Thus strong graphene-to-oxide charge transfer aids nucleation of graphene on incommensurate oxide substrates

Atomic layer deposition of BN as a novel capping barrier for B2O3

Article demonstrating in situ deposition of BN by sequential BCl₃/NH₃ reactions at 600 K on two different oxidized boron substrates: (a) B₂O₃ deposited using BCl₃/H₂O ALD on Si at 300 K (“B₂O₃/Si”) and (b) a boron-silicon oxide formed by sequential BCl₃/O₂ reactions at 650 K on SiO₂ followed by annealing to 1000 K (“B-Si-oxide”). The data presented demonstrates that ultrathin BN films deposited by BCl₃/NH₃ ALD are promising candidates for passivation of boron oxide used in shallow doping applications

Ordered three-fold symmetric graphene oxide/buckled graphene/graphene heterostructures on MgO(111) by carbon molecular beam epitaxy

Theory and experiment demonstrate the direct growth of a graphene oxide/buckled graphene/graphene heterostructure on an incommensurate MgO(111) substrate. X-ray photoelectron spectroscopy, electron energy loss, Auger electron spectroscopy, low energy electron diffraction, Raman spectroscopy and first-principles density functional theory (DFT) calculations all demonstrate that carbon molecular beam epitaxy on either a hydroxylated MgO(111) single crystal or a heavily twinned thin film surface at 850 K yields an initial C layer of highly ordered graphene oxide with C_(3v) symmetry. A 5 × 5 unit cell of carbon, with one missing atom, forms on a 4 × 4 unit cell of MgO, with the three C atoms surrounding the C vacancy surface forming covalent C–O bonds to substrate oxide sites. This leads to a bowed graphene-oxide with slightly modified D and G Raman lines and a calculated band gap of 0.36 eV. Continued C growth results in the second layer of graphene that is stacked AB with respect to the first layer and buckled conformably with the first layer while maintaining C_(3v) symmetry, lattice spacing and azimuthal orientation with the first layer. Carbon growth beyond the second layer yields graphene in azimuthal registry with the first two C layers, but with graphene-characteristic lattice spacing and π → π* loss feature. This 3rd layer is also p-type, as indicated by the 5.6 eV energy loss feature. The significant sp^3 character and C_(3v) symmetry of such heterostructures suggest that spin–orbit coupling is enabled, with implications for spintronics and other device applications

Direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon

Article on direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon

Possible Detection of Low Energy Solar Neutrons Using Boron Based Materials

Solar neutrons have been detected aboard the International Space Station (ISS), using lithium tetraborate and boron carbide detector elements. We find that evidence of a solar neutron flux, as detected in a neutron calorimeter following subtraction of the proton background, with an energy of about 2 to 4 MeV. This solar neutron flux is likely no more than 250 to 375 neutrons cm−2sec−1, with a lower bound of 50–75 neutrons cm−2sec−1 at one au

Films for Use in Microelectronic Devices and Methods of Producing Same

Patent relating to the use of films in microelectronic devices and methods of producing same

Methods of Forming Graphene/(Multilayer) Boron Nitride for Electronic Device Applications

Patent relating to methods of forming graphene/(multilayer) boron nitride for electronic device applications

Film for Use in Microelectronic Devices and Methods of Producing Same

Patent relating to film for use in microelectronic devices and methods of producing same

Graphene/(Multilayer) Boron Nitride Heteroepitaxy for Electronic Device Applications

Patent relating to graphene/(multilayer) boron nitride heteroepitaxy for electronic device applications