Saji, K J; Dr.Jayaraj, M K(Cochin University of Science & Technology, October , 2008)
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Abstract:
This work
mainly concentrate to understand the optical and electrical properties of
amorphous zinc tin oxide and amorphous zinc indium tin oxide thin films
for TFT applications. Amorphous materials are promising in achieving
better device performance on temperature sensitive substrates compared
to polycrystalline materials. Most of these amorphous oxides are multicomponent
and as such there exists the need for an optimized chemical
composition. For this we have to make individual targets with required
chemical composition to use it in conventional thin film deposition techniques
like PLD and sputtering. Instead, if we use separate targets for
each of the cationic element and if separately control the power during the
simultaneous sputtering process, then we can change the chemical composition
by simply adjusting the sputtering power. This is what is done in co-sputtering technique. Eventhough there had some reports about thin
film deposition using this technique, there was no reports about the use
of this technique in TFT fabrication until very recent time. Hence in this
work, co-sputtering has performed as a major technique for thin film deposition
and TFT fabrication. PLD were also performed as it is a relatively
new technique and allows the use high oxygen pressure during deposition.
This helps to control the carrier density in the channel and also favours the
smooth film surface. Both these properties are crucial in TFT.Zinc tin oxide material is interesting in the sense that it does not contain
costly indium. Eventhough some works were already reported in ZTO based
TFTs, there was no systematic study about ZTO thin film's various optoelectronic
properties from a TFT manufacturing perspective. Attempts
have made to analyse the ZTO films prepared by PLD and co-sputtering.
As more type of cations present in the film, chances are high to form an
amorphous phase. Zinc indium tin oxide is studied as a multicomponent
oxide material suitable for TFT fabrication.
Description:
Department of Physics,
Cochin University of Science and Technology