| dc.description.abstract |
The main objective of the present study is to understand different mechanisms
involved in the production and evolution of plasma by the pulsed laser ablation
and radio frequency magnetron sputtering. These two methods are of particular
interest, as these are well accomplished methods used for surface coatings,
nanostructure fabrications and other thin film devices fabrications. Material
science researchers all over the world are involved in the development of
devices based on transparent conducting oxide (TCO) thin films. Our laboratory
has been involved in the development of TCO devices like thin film diodes
using zinc oxide (ZnO) and zinc magnesium oxide (ZnMgO), thin film
transistors (TFT's) using zinc indium oxide and zinc indium tin oxide, and some
electroluminescent (EL) devices by pulsed laser ablation and RF magnetron
sputtering.In contrast to the extensive literature relating to pure ZnO and other thin films
produced by various deposition techniques, there appears to have been relatively
little effort directed towards the characterization of plasmas from which such
films are produced. The knowledge of plasma dynamics corresponding to the
variations in the input parameters of ablation and sputtering, with the kind of
laser/magnetron used for the generation of plasma, is limited. To improve the
quality of the deposited films for desired application, a sound understanding of
the plume dynamics, physical and chemical properties of the species in the
plume is required. Generally, there is a correlation between the plume dynamics
and the structural properties of the films deposited. Thus the study of the
characteristics of the plume contributes to a better understanding and control of
the deposition process itself. The hydrodynamic expansion of the plume, the composition, and SIze distribution of clusters depend not only on initial
conditions of plasma production but also on the ambient gas composition and
pressure. The growth and deposition of the films are detennined by the
thermodynamic parameters of the target material and initial conditions such as
electron temperature and density of the plasma.For optimizing the deposition parameters of various films (stoichiometric or
otherwise), in-situ or ex-situ monitoring of plasma plume dynamics become
necessary for the purpose of repeatability and reliability. With this in mind, the
plume dynamics and compositions of laser ablated and RF magnetron sputtered
zinc oxide plasmas have been investigated. The plasmas studied were produced
at conditions employed typically for the deposition of ZnO films by both
methods. Apart from this two component ZnO plasma, a multi-component
material (lead zirconium titanate) was ablated and plasma was characterized. |
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