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_0.103La_0.897O_y gate dielectric shows high performance such as high carrier mobility of 3.45 cm² V¹. s¹ (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 HfO₂. Atomic force microscope reveals that the La incorporation can reduce the surface roughness of the gate dielectric by suppressing the crystallization of HfO₂. Therefore, by using Hf_0.103La_0.897O_y as gate dielectric, OTFT with high carrier mobility and small threshold voltage can be obtained.