Investigation of pentacene growth on SiO_2 gate insulator after photolithography for nitrogen-doped LaB_6 bottom-contact electrode formation

摘要

Nitrogen-doped (N-doped) LaB6 is a candidate material for the bottom-contact electrode of n-type organic field-effect transistors (OFETs). However, the formation of a N-doped LaB6 electrode affects the surface morphology of a pentacene film. In this study, the effects of surface treatments and a N-doped LaB6 interfacial layer (IL) were investigated to improve the pentacene film quality after N-doped LaB6 electrode patterning with diluted HNO3, followed by resist stripping with acetone and methanol. It was found that the sputtering damage during N-doped LaB6 deposition on a SiO2 gate insulator degraded the crystallinity of pentacene. The H2SO4 and H2O2 (SPM) and diluted HF treatments removed the damaged layer on the SiO2 gate insulator surface. Furthermore, the N-doped LaB6 IL improved the crystallinity of pentacene and realized dendritic grain growth. Owing to these surface treatments, the hole mobility improved from 2.8 x 10(-3) to 0.11 cm(2)/(V.s), and a steep subthreshold swing of 78 mV/dec for the OFET with top-contact configuration was realized in air even after bottom-contact electrode patterning. (C) 2018 The Japan Society of Applied Physics.