The Role of the Charge State of Surface Atoms of a Metal Substrate in Doping of Quasi-Free-Standing Graphene

Cr has significant influence on the formation, charge state, relative stability and equilibrium configuration of isolated intrinsic point defects in α-Al2O3, resulting in the variation of defect process in α-Al2O3.

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Electrical Transport in Mesoporous Silicon Layers

MRS Proceedings ◽

10.1557/proc-358-575 ◽

1994 ◽

Vol 358 ◽

Cited By ~ 4

Author(s):

M. Ben-Chorin ◽

S. Grebner ◽

F. Wang ◽

R. Schwarz ◽

A. Nikolov ◽

...

Keyword(s):

Electrical Transport ◽

Surface States ◽

Dark Conductivity ◽

Free Standing ◽

Electron Conduction ◽

Mesoporous Silicon ◽

Methanol Vapor ◽

Quantum Confinement Effects ◽

P Type

ABSTRACTIn order to clarify the role of the enlarged surface area of porous silicon on the electrical conductivity, we have studied the transport in mesoporous silicon layers, for which quantum confinement effects are negligible. We prepare free standing mesoporous films, from highly doped p-type Si wafers. The dark conductivity of the mesoporous layers is activated with an energy of 0.5 eV. Thermopower measurements show negative sign indicating electron conduction. The exposure of these layers to methanol vapor results in an increased conductivity and change of the thermopower magnitude. Photoconductivity measurements and the Steady-State Photocarrier Grating technique (SSPG) are used to evaluate the density of the surface states and the dynamics of the photo-excited carriers. All these results indicate that a large density of surface states exist, which results in a depletion of the free holes.

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Dependence of the Sn0/2+ charge state on the Fermi level in semi-insulating CdTe

Journal of Materials Research ◽

10.1557/jmr.2007.0404 ◽

2007 ◽

Vol 22 (11) ◽

pp. 3249-3254 ◽

Cited By ~ 22

Author(s):

V. Babentsov ◽

J. Franc ◽

H. Elhadidy ◽

A. Fauler ◽

M. Fiederle ◽

...

Keyword(s):

Fermi Level ◽

Charge State ◽

Strong Dependence ◽

High Resistivity ◽

Level Variation ◽

Radiative Transitions ◽

Deep Traps ◽

First Time ◽

Positively Charged

We explored the growth and characteristics of CdTe doped with Sn to heighten our understanding of the role of deep levels on electrical compensation and trapping. We demonstrated, for the first time, the strong dependence of the SnCd charge state on the Fermi-level variation (2–3kT) in high-resistivity CdTe. The concentration of deep traps for electrons was determined by the number of doubly positively charged Sn2+ atoms. Thermoelectric-effect spectroscopy and photovoltage measurements revealed the conversion of the SnCd defect from the electron SnCd2+ trap to the hole SnCd0 trap. The results agree well with the existence of a negative U-center in the SnCd0/2+ defect. We also showed that the neutral Sn defect is responsible for the near midgap C-band → bound hole radiative transitions band with a maximum at 0.76 eV.

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Humidifier-associated paediatric Legionnaires' disease, Israel, February 2012

Eurosurveillance ◽

10.2807/ese.17.41.20293-en ◽

2012 ◽

Vol 17 (41) ◽

Author(s):

J Moran-Gilad ◽

T Lazarovitch ◽

M Mentasti ◽

T Harrison ◽

M Weinberger ◽

...

Keyword(s):

Legionella Pneumophila ◽

Cold Water ◽

Tap Water ◽

Fatal Case ◽

Control Measures ◽

Free Standing ◽

Legionnaires Disease

We report a fatal case of community-acquired Legionnaires' disease in an infant aged under six months. Epidemiological and microbiological investigations suggested that a free-standing cold water humidifier using domestic tap water contaminated with Legionella pneumophila serogroup 1 served as a vehicle for infection. These findings were corroborated by sequence-based typing (SBT). Humidifier-associated Legionnaires' disease can be prevented by appropriate control measures. This case also illustrates the emerging role of SBT in the investigation of legionellosis.

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