Photoreflectance characterization of GaAs as a function of temperature, carrier concentration, and near-surface electric field

1993 ◽  
Vol 11 (2) ◽  
pp. 169 ◽  
Author(s):  
Ali Badakhshan
Keyword(s):  
Electric Field ◽  
Carrier Concentration ◽  
Near Surface ◽  
Surface Electric Field

Characterization of Si wafers by μ-PCD with surface electric field

2000 ◽  
Vol 73 (1-3) ◽  
pp. 230-234 ◽  
Author(s):  
M Ichimura ◽  
M Hirano ◽  
A Tada ◽  
E Arai ◽  
H Takamatsu ◽  
...  
Keyword(s):  
Electric Field ◽  
Surface Electric Field

Reflection anisotropy spectroscopy study of the near surface electric field in low-temperature grown GaAs (001)

1997 ◽  
Vol 70 (9) ◽  
pp. 1107-1109 ◽  
Author(s):  
Todd Holden ◽  
Fred H. Pollak ◽  
J. L. Freeouf ◽  
D. McInturff ◽  
J. L. Gray ◽  
...  
Keyword(s):  
Low Temperature ◽  
Electric Field ◽  
Spectroscopy Study ◽  
Near Surface ◽  
Surface Electric Field ◽  
Low Temperature Grown Gaas

Implications of the Born approximation for the magnetotelluric problem in three‐dimensional environments

Geophysics ◽  
1992 ◽  
Vol 57 (4) ◽  
pp. 587-602 ◽  
Author(s):  
Carlos Torres‐Verdín ◽  
Francis X. Bostick
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Born Approximation ◽  
Transfer Functions ◽  
Pass Filter ◽  
Near Surface ◽  
Low Pass ◽  
Surface Electric Field ◽  
Subsurface Resistivity ◽  
Lateral Variations

A first‐order Born approximation is obtained for the integral equations governing the surface magnetotelluric response over a three‐dimensional earth. Although accurate only in cases of low resistivity contrasts, the resulting expressions: (1) exhibit a linear relationship between a spatial perturbation in subsurface resistivity and the ensuing perturbation on the surface field response, and, more importantly, (2) allow arbitrary degrees of complexity in the geometrical characteristics of the subsurface. The linear system solutions derived from the Born approximation are studied by examining the properties of their associated kernels. These kernels may be thought of as a suite of horizontal magnetotelluric “wavelets” weighting the subsurface resistivity distribution at different depth levels. Analytical expressions for the wavelets are obtained in the wavenumber domain, thus generating a suite of magnetotelluric “transfer functions.” Expressions for the latter are particularized to the cases of one‐ and two‐dimensional geolectric media yielding results consistent with the characteristics of the magnetotelluric fields known to hold in these low‐order environments. Inspection of the electric transfer functions reveals severe sensitivity to near‐surface lateral variations of resistivity, which persists even at deep sensing frequencies. This near‐surface sensitivity is the result of an additive term in the electric field transfer functions, the static component, acting as a spatial highpass filter of the lateral variations of surface resistivity. A second additive component in the electric transfer functions, the induction component, functions as a spatial lowpass filter of the lateral variations in subsurface resistivity, and is primarily responsible for the inductive part of the surface electric field response. A common problem in magnetotelluric interpretation, the electric static effect can be reduced by inverting the role of the static component, i.e., by spatially low‐pass filtering the surface electric field. The suggested low‐pass filter for such an operation is one for which the cutoff wavenumber increases with frequency and is therefore insensitive to the response from the induction component. Low‐pass filtering of the surface electric field is best implemented in the field if the electric dipoles are deployed end‐to‐end continuously along a survey path. The magnetic field transfer functions, on the other hand, exhibit a single induction term with band‐pass filter properties which may actually lead to some amount of local distortion on the measured surface magnetic field. We propose to reduce this distortion by referring all electric field measurements to the primary magnetic field within the survey area. The primary magnetic field components, in turn, can be estimated by the spatial average of the magnetic measurements acquired at an array of magnetic stations. The suggested procedures for both the acquisition and processing of natural electric and magnetic field data encompass altogether a novel adaptation of the magnetotelluric method.

scholarly journals Simulation of the Electric Field Distribution Near a Topographically Nanostructured Titanium-Electrolyte Interface: Influence of the Passivation Layer

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Andreas Körtge ◽  
Patrick Elter ◽  
Regina Lange ◽  
Ulrich Beck
Keyword(s):  
Electric Field ◽  
Protein Adsorption ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Passivation Layer ◽  
Near Surface ◽  
Sharp Edges ◽  
Surface Electric Field ◽  
Poisson Boltzmann Equation ◽  
Field Strengths

A major challenge in biomaterials research is the regulation of protein adsorption at metallic implant surfaces. Recently, a number of studies have shown that protein adsorption can be influenced by metallic nanotopographies, which are discussed to increase electric field strengths near sharp edges and spikes. Since many metallic biomaterials form a native passivation layer with semiconducting properties, we have analyzed the influence of this layer on the near-surface electric field distribution of a nanostructure using finite element simulations. The Poisson-Boltzmann equation was solved for a titanium nanostructure covered by a TiO2passivation layer in contact with a physiological NaCl solution (bulk concentration 0.137 mol/L). In contrast to a purely metallic nanostructure, the electric field strengths near sharp edges and spikes can be lower than in planar regions if a passivation layer is considered. Our results demonstrate that the passivation layer has a significant influence on the near-surface electric field distribution and must be considered for theoretical treatments of protein adsorption on passivated metals like titanium.

scholarly journals Study of Atmospheric Discharges by Near Surface Electric Field Measurements

2018 ◽  
Vol 12 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Hripsime Mkrtchyan
Keyword(s):  
Electric Field ◽  
Field Measurements ◽  
Cosmic Ray ◽  
Physics Institute ◽  
Near Surface ◽  
Recovery Curves ◽  
Yerevan Physics Institute ◽  
Surface Electric Field ◽  
Atmospheric Discharges ◽  
Electric Field Measurements

Background:In this work the disturbances of the near surface electric field are investigated, which are attributed to different types of atmospheric discharges: intracloud or cloud-to-ground.Method:The patterns of the lightning occurrences are discussed as measured by the network of the electric field mills located at the stations of Cosmic Ray Division of Yerevan Physics Institute. Discharges make changes in the near surface electric field, which can be separated into two groups. The differences of those two groups and shapes of the recovery curves are discussed using the data from electric field mills network for a stormy day on May 23, 2015.Conclusion:The results presented in this work show that magnitudes of field changes from one of the groups are larger and have shorter duration compared to another one. Recovery curves of the near surface electric field produced by lightning flashes also have a power-law or a linear dependence besides exponential shape.

Modification of the p-GaP(001) work function by surface dipole bonds formed in sulfide solution

2019 ◽  
Vol 7 (24) ◽  
pp. 7327-7335 ◽  
Author(s):  
Mikhail V. Lebedev ◽  
Peter A. Dementev ◽  
Tatiana V. Lvova ◽  
Vladimir L. Berkovits
Keyword(s):  
Electric Field ◽  
Work Function ◽  
Ionization Energy ◽  
Near Surface ◽  
Dipole Layer ◽  
Surface Electric Field ◽  
Surface Dipole ◽  
Sulfide Solution

Sulfur treatment of p-GaP(001) surfaces increases the ionization energy and near-surface electric field due to a dipole layer consisting of gallium sulfates.

Surface Self-Diffusion Instability in Electric Fields

2000 ◽  
Vol 648 ◽  
Author(s):  
Michael I. Ojovan ◽  
Pavel P. Poluectov
Keyword(s):  
Electric Field ◽  
Diffusion Processes ◽  
Strong Electric Field ◽  
Electrical Field ◽  
Initial Shape ◽  
Near Surface ◽  
Self Diffusion ◽  
Surface Molecules ◽  
Surface Electric Field ◽  
Plane Form

AbstractThe plane form is the equilibrium one for surfaces of condensed matter. Deviations can be caused usually by crystal structure. Herein we will describe an effect of surface instability due to self- diffusion processes of atoms and molecules in the near surface electric field.Self-diffusion processes (as it was shown by Mullins) cause relaxation of any deviation (protuberance) from the plane form due to the increased concentration of surface atoms and its consequent smoothing. This process we studied for the case when there is an electric field near the surface. The near surface electric field can be due to either the location of material in an external (homogeneous or inhomogeneous) electrical field or self-charges on the surface. There is an increasing of electric field intensity near protuberances both in external and self-formed electrical fields: the higher is the curvature of surface the stronger is the intensity of the near surface electrical field. Consequently two competing processes occur during surface molecules mass transfer: both the self- diffusion smoothing of surface molecule concentration and drawing of molecules in the strong electric field regions. Depending on the initial shape of the protuberance either relaxation or instability occurs. There is a critical wavelength λ0=RskBT/2Uz, which shows that shorter wavelength deviations decrease their amplitudes and longer wavelength deviations grow in amplitude by time. Here Rs is characteristic of the material, T is temperature, and Uz is the interaction energy of surface molecules with the electric field. Since there are random variations of any surface from the plane form, being placed in an electric field these surfaces will be unstable depending on the intensity of electric field and properties of material.

Photoreflectance Characterization of InGaAs/GaAs Superlattices Grown on [111]-Oriented Substrates

1993 ◽  
Vol 324 ◽  
Author(s):  
R. G. Rodrigues ◽  
K. Yang ◽  
L. J. Schowalter ◽  
J. M. Borrego
Keyword(s):  
Electric Field ◽  
Quantum Wells ◽  
Photovoltaic Effect ◽  
Quantum Structures ◽  
Optical Transitions ◽  
Linear Absorption ◽  
Free Carriers ◽  
Gaas Substrates ◽  
Surface Electric Field

AbstractWe report the results of a photoreflectance (PR) study of InGaAs/GaAs strained-layer quantum wells and superlattices (SLSs) grown by MBE on [111]B GaAs substrates. Under our measurement conditions, the PR spectra display features we can relate to the bandgaps of both materials and to optical transitions in the quantum structures. Using the photovoltaic effect to vary the surface electric field of our i-n+ and p+-i-n+ samples in a strictly contactless manner, we find optical transitions red-shifting with increasing intensity of illumination from a CW HeNe laser in [111]-grown structures, a well known effect which can be attributed to the straingenerated electric field (SGEF) present in these structures. We also find experimental support for the predicted effectiveness of free-carriers in screening the SGEF and thereby originating highly non-linear absorption.

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