| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 81 === With regard to the unpassivated poly-Si TFTs with undoped
channel, the magnitude of the threshold voltage is greater than
5V and the leakage current is usually not available. Thus the
necessary channel doping and hydrogenation are required to
reduce threshold voltages to acceptable values. In this thesis
, we have studied the characteristics of the p-channel TFTs
with boron and arsenic implantation doses before and
after hydrogenation. From the experimental results, it is seen
that the thicker films of 86nm exhibit the characteristics just
as those we have predicted that the threshold voltage
increases with the channel arsenic dose and decreases with
the channel boron dose for properly channel implantation.
However, the thinner films of 26nm show the features of
passivation for very lightly channel implantation. In addition,
it is seen that the increase of the Source/Drain resistance
after hydrogenation becomes more significant as the thickness
of the polysilicon is scaled down. Therefore, though the TFT
with thinner channel thickness(26nm) exhibits better
characteristics, its on current is limited by the drastically
increased Source/Drain resistance after hydrogenation. In view
of the reason mentioned aboved, it is recommended that the
length of Source/Drain region should be decreased in order to
minimize the influence of Source/Drain resistance on electrical
characteristics.
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