STRUCTURE AND ELECTRICAL PROPERTIES OF ELECTRON-BEAM EVAPORATED ZIRCONIA THIN FILMS
STRUCTURE AND ELECTRICAL PROPERTIES OF ELECTRON-BEAM EVAPORATED ZIRCONIA THIN FILMS
No Thumbnail Available
Date
1982-09
Authors
Paul, Ben Onaji
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
In the past 25 years, there has been much interest in dielectric
films of Zr02 for several applications such as an alternative insulator
material in microelectronics, resistance switching and an oxygen anion
conductor. Only recently have thin film anion conductors, especially
the cubic Zr02 form, been investigated. However, these films will
probably find future uses such as solid electrolytes for thermodynamic
and kinetic purposes, for purification and preparation of gases, and in
oxygen monitoring suysterns.
Zirconia films have been prepared by a variety of methods but
electron-beam (E-beam) evaporation has had limited characterization.
The objective of this investigation was to study the structure and
electrical properties of E-beam evaporated Mo-Zr02-Ho capacitors as a
function of deposition temperature. In addition, Y2O3 stabilized Zr02
films were prepared by a new method, E-beam multilayer deposition, and
characterized in terms of structure and electrical properties.
Zirconia films deposited on molybdenum electrodes were
polycrystalline. The raonoclinic phase was the major phase detected in
the films deposited at temperatures between 300°C and 600°C. At lower
deposition temperatures (190o -200o C), however, the cubic phase was the
major crystalline phase formed. The average crystallite size increased
from 118 A to 484 A for the (111) and 175 A to 265 A for the (111)
crystallites as deposition temperature increased from 200°C to 600°C.
Ac conduction in Mo-Zr02-Ho structures at fields < 0.0 5 MV/cm
was dominated by electron hop with a frequency independent loss behavior
between 25°C and 150°C. Between 150°C and 325°C, a od « fY
dependence was observed where y depended on measurement and deposition
temperatures. The remanance of interfacial polarization is suggested as
an additional mechanism in this temperature range and for frequencies of
60-105 Hz. The admittance plots of the samples showed a single
semicircle with a small semicircle depression that was ascribed to bulk
conduction.
Both ohmic and space-charge-limited-currents (SCLC) dc conduction
were obtained for the Mo-Zr02-Ho samples. The charge storage in these
films increased linearly with voltage and depended on measurement and
deposition temperatures, but was probably polarity independent.
Y2O3 stabilized Zr02 films could be formed by multilayer
deposition followed by heat treatment at 1200°C for at least seven
hours. Heat treated Au/Pd-Y203,Zr02 Pt/Rd capacitors exhibited a SCLC
behavior at a field of 0.03 MV/cm and room temperature. The admittance
plot of this sample had a large semicircle depression of about 45°.
Description
A Dissertation
Presented to
The Faculty of the Division of Graduate Studies
BY
Paul Ben Onaji
In Partial Fulfillment
of the Requirements for the Degree of
Doctor of Philosophy
in the School of Ceramic Engineering
Georgia Institute of Technology
September, 1982
Keywords
STRUCTURE,, ELECTRICAL,, PROPERTIES,, ELECTRON-BEAM,, EVAPORATED,, ZIRCONIA,