Comparison of HiPIMS and conventional sputtering methods used for preparation of
transparent IGZO thin films
Pavel Baroch, Jiri Rezek, Tomas Kozak, Jiri Houska
Department of Physics and NTIS - European Centre of Excellence, University of West
Bohemia, Univerzitni 8, 306 14 Plzen, Czech Republic
Transparent semiconducting amorphous IGZO films have attracted great attention due to
their excellent electrical properties and possible utilization in thin film transistors or in
photovoltaic applications. It is known that the properties of IGZO films are highly sensitive
to process parameters, especially to oxygen partial pressure. In this study we have focused on
the properties of transparent semiconducting amorphous indium gallium zinc oxide (IGZO)
thin films prepared by conventional sputtering methods and those prepared by high power
impulse magnetron sputtering (HiPIMS) in order to optimize electrical and optical properties
of the IGZO thin films and to investigate possibility to apply these coatings on thermally
sensitive flexible substrates. We employed dc, pulsed dc, mid frequency sine wave and
HiPIMS power supplies for magnetron deposition. Magnetrons were equipped with ceramic
InGaZnO targets. In all experiments we focused on the effect of oxygen partial pressure,
discharge power and pulsed power mode on the electrical, optical and mechanical properties
of IGZO thin films and also on the thermal load deposited to the substrate. We have observed
a very fast transition between low- and high- resistivity films depending on oxygen partial
pressure. It is shown that the electrical resistivity can be effectively controlled in the wide
range from of values 10
-2
to 10
11
.cm. The highest mobility of charge carriers (up to 50
cm
2
/V.s) was obtained at very low oxygen partial pressures. Utilization of HiPIMS also led to
significant decrease in thermal load deposited to the substrate which is beneficial for
deposition on the thermally sensitive and flexible polymer substrates. Deposition rate as a
function of discharge power and oxygen partial pressure was also systematically investigated
and the results from optical, electrical and structure analysis will be discussed in detail.
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