Investigation on electrical charging/discharging properties of thin ps/pmma polymeric films by dynamic x-ray photoelectron spectroscopy
Author(s)
Advisor
Süzer, ŞefikDate
2008Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Electrical charging/discharging properties of thin layers of spin coated pure PS
polystyrene (PS), and pure poly(methyl methacrylate), (PMMA) and an immiscible
PS/PMMA blend are studied with externally applied DC and dynamic(squarewave stress)
X-Ray Photoelectron Spectroscopy (XPS).
PS and PMMA exhibit quite different charging properties under DC stress. Due to
the different charging properties of PS and PMMA domains within an immiscible
PS/PMMA blend film, charge contrast or phase separation is clearly observed between
domains. Electrical parameters of PS and PMMA thin films while employing a squarewave
pulse stress in a 10-3 - 103
Hz range of frequency are probed by dynamic XPS. A model,
which can simulate the dynamical XPS measurements, is shown to lead to obtain effective
resistance and capacitance values for each polymer. RC time constants and inflection
points(frequency) are also determined. Moreover, thickness also affects the
charging/discharging properties and other electrical parameters of polymeric thin films.
Furthermore, to mimic certain dielectric properties of thin polymeric films and to validate
our model, we have included an externally RC circuit to a conducting graphite sample
under both DC and squarewave pulse stresses.
Keywords
XPSDynamic XPS
Charging
Differential Charging
Time Constant
Charge Contrast
Phase Seperation
Simulation