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 Hf0.103La0.897Oy 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 spectrumindicates 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 Hf0.103La0.897Oy as gate dielectric, OTFT with high carrier mobility and small threshold voltage can be obtained.