A Study on Organic Thin-Film Transistors Using Hf–La Oxides With Different La Contents as Gate Dielectrics

The effects of La content in HfLaO gate dielectric on the performance of pentacene organic thin-film transistor (OTFT) fabricated on Si have been studied. The OTFT with Hf
_0.103
La
_0.897
O
_y
gate dielectric shows high performance such as high carrier mobility of 3.45 cm
²
·V
^-1
·s
^-1
(132 times and 40 times higher than those of devices using Hf oxide and La oxide, respectively), small threshold voltage of -2.09 V, and negligible hysteresis of -0.029 V. Binding-energy shift of Hf 4f peak in the X-ray photoelectron spectroscopy spectrum indicates that La incorporation can passivate the oxygen vacancies in HfO
₂
. Atomic force microscope reveals that the La incorporation can reduce the surface roughness of the gate dielectric by suppressing the crystallization of HfO
₂
. Therefore, by using Hf
_0.103
La
_0.897
O
_y
as gate dielectric, OTFT with high carrier mobility and small threshold voltage can be obtained.