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@PHDTHESIS{Dylla:44172,
author = {Dylla, Thorsten},
title = {{E}lectron {S}pin {R}esonance and {T}ransient
{P}hotocurrent {M}easurements on {M}icrocrystalline
{S}ilicon},
volume = {43},
school = {Freie Universität Berlin},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-44172},
series = {Schriften des Forschungszentrums Jülich. Reihe
Energietechnik / energy technology},
pages = {X, 138 S.},
year = {2004},
note = {Record converted from VDB: 12.11.2012; Freie Universität
Berlin, Diss., 2004},
abstract = {The electronic properties of microcrystalline silicon
(μc-Si:H) films have been studied using electron spin
resonance (ESR), transient photocurrent time-of-flight (TOF)
techniques, and electrical conductivity measurements.
Structural properties were determined by Raman spectroscopy.
A wide range of structure compositions, from highly
crystalline films with no discernable amorphous content, to
predominantly amorphous films with no crystalline phase
contributions, was investigated. Models and possible
explanations concerning the nature and energetic
distribution of electronic defects as a function of film
composition are discussed. It is shown that the spin density
N$_{S}$ in μc-Si:H films is linked strongly to the
structure composition of the material. The highest N$_{S}$
is always found for material with the highest crystalline
volume fraction. With increasing amorphous content, N$_{S}$
decreases, which is attributed to increasing hydrogen
content and improved termination of dangling bonds.
Moreover, the amorphous phase content, incorporated between
the crystalline columns, appears to act as a passivation
layer, leading to more effective termination of unsatisfied
bonds at the column boundaries. Both reversible and
irreversible changes in the ESR signal and dark conductivity
due to atmospheric effects are found in μc-Si:H. These are
closely connected to the structure composition, in
particular the active surface area. The porous structure of
highly crystalline material facilitates in-diffusion of
atmospheric gases, which strongly affects the character
and/or density of surface states. Two contributing processes
have been identified, namely adsorption and oxidation. Both
processes lead to an increase of N$_{S}$. In the case of
adsorption the increase is identified as arising from
changes of the db2 resonance (g=2.0052), while the intensity
of the db1 resonance (g=2.0043) remains constant. With
increasing amorphous content the magnitude of both
adsorption and oxidation induced changes decreases, which
may be linked to the greater compactness of such films.
Measurements on n-type μc-Si:H films were used as a probe
of the density of gap states, confirming that the spin
density NS is related to the density of defects. The results
confirm that for a wide range of structural compositions,
the doping induced Fermi level shift in μc-Si:H is governed
by compensation of defect states, [...]},
cin = {IPV},
cid = {I:(DE-Juel1)VDB46},
pnm = {Photovoltaik},
pid = {G:(DE-Juel1)FUEK247},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/44172},
}