posted on 2020-03-18, 20:43authored byYoung
Hun Kang, Bok Ki Min, Seong K. Kim, Garam Bae, Wooseok Song, Changjin Lee, Song Yun Cho, Ki-Seok An
Perhydropolysilazane
(PHPS), an inorganic polymer composed of Si–N
and Si–H, has attracted much attention as a precursor for gate
dielectrics of thin-film transistors (TFTs) due to its facile processing
even at a relatively low temperature. However, an in-depth understanding
of the tunable dielectric behavior of PHPS-derived dielectrics and
their effects on TFT device performance is still lacking. In this
study, the PHPS-derived dielectric films formed at different annealing
temperatures have been used as the gate dielectric layer for solution-processed
indium zinc oxide (IZO) TFTs. Notably, the IZO TFTs fabricated on
PHPS annealed at 350 °C exhibit mobility as high as 118 cm2 V–1 s–1, which is about
50 times the IZO TFTs made on typical SiO2 dielectrics.
The outstanding electrical performance is possible because of the
exceptional capacitance of PHPS-derived dielectric caused by the limited
hydrolysis reaction of PHPS at a low processing temperature (<400
°C). According to our analysis, the exceptional dielectric behavior
is originated from the electric double layer formed by mobile of protons
in the low temperature-annealed PHPS dielectrics. Furthermore, proton
conduction through the PHPS dielectric occurs through a three-dimensional
pathway by a hopping mechanism, which allows uniform polarization
of the dielectric even at room temperature, leading to amplified performance
of the IZO TFTs.