TITLE:
AC Impedance Spectroscopy of a-nc-Si:H Thin Films
AUTHORS:
Vladimir Tudić
KEYWORDS:
a-nc-Si:H, Impedance Spectroscopy, Composite Thin Film, Equivalent Circuit
JOURNAL NAME:
Engineering,
Vol.6 No.8,
July
11,
2014
ABSTRACT: The AC impedance of
amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) from mHz to
MHz at different temperatures has been studied. The samples were prepared by
Plasma Enhanced Chemical Vapor Deposition technique. The X-ray diffraction and
high resolution electron microscopy showed that films consist of isolated nano-crystals
embedded in amorphous matrix. In analysis of impedance data, two approaches
were tested: the ideal Deby type equivalent circuit and modified one, with CPE
(constant phase elements). It was found that the later better fits to results.
The amorphous matrix showed larger resistance and lower capacity than nano-crystals.
By heat treatment in vacuum, the capacity for both phases changes, according to
expected change in size of ordered domains.