53 research outputs found
Sensitivity of Second Harmonic Generation to Space Charge Effects at Si(111)/Electrolyte and Si(111)/SiO\u3csub\u3e2\u3c/sub\u3e/Electrolyte Interfaces
The potential dependence in the surface second harmonic response from hydrogen terminated n‐Si(111) and oxidized n‐Si(111) surfaces has been examined in aqueous NH4F and H2SO4 solutions. The relative phase of the nonlinear response as measured by rotational anisotropy experiments is found to be highly sensitive to the presence of the oxide and the field applied across the Si(111)/oxide/electrolyte interface. These observations are attributed to field effects within the space–charge region of the semiconductor which vary with the presence and thickness of the insulating oxide layer on the Si(111) surface
DC-electric-field-induced and low-frequency electromodulation second-harmonic generation spectroscopy of Si(001)-SiO interfaces
The mechanism of DC-Electric-Field-Induced Second-Harmonic (EFISH) generation
at weakly nonlinear buried Si(001)-SiO interfaces is studied experimentally
in planar Si(001)-SiO-Cr MOS structures by optical second-harmonic
generation (SHG) spectroscopy with a tunable Ti:sapphire femtosecond laser. The
spectral dependence of the EFISH contribution near the direct two-photon
transition of silicon is extracted. A systematic phenomenological model of the
EFISH phenomenon, including a detailed description of the space charge region
(SCR) at the semiconductor-dielectric interface in accumulation, depletion, and
inversion regimes, has been developed. The influence of surface quantization
effects, interface states, charge traps in the oxide layer, doping
concentration and oxide thickness on nonlocal screening of the DC-electric
field and on breaking of inversion symmetry in the SCR is considered. The model
describes EFISH generation in the SCR using a Green function formalism which
takes into account all retardation and absorption effects of the fundamental
and second harmonic (SH) waves, optical interference between field-dependent
and field-independent contributions to the SH field and multiple reflection
interference in the SiO layer. Good agreement between the phenomenological
model and our recent and new EFISH spectroscopic results is demonstrated.
Finally, low-frequency electromodulated EFISH is demonstrated as a useful
differential spectroscopic technique for studies of the Si-SiO interface in
silicon-based MOS structures.Comment: 31 pages, 14 figures, 1 table, figures are also available at
http://kali.ilc.msu.su/articles/50/efish.ht
Bridging the Pressure Gap in Water and Hydroxyl Chemistry on Metal Surfaces: The Cu(110) Case
Computational Studies of Load-Dependent Guest Dynamics and Free Energies of Inclusion for CO 2
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