| 초록 |
Organic field effect transistors (OFETs) have received considerable interest in recent years and intensive studies have made it possible to achieve device performance comparable to that of amorphous silicon transistors. OFETs with organic semiconductors, however, are generally limited by relatively high operating voltage, typically ＞ 20V owing to the low capacitance of gate dielectrics such as thick SiO2 or polymer film and the high defect state density in organic semiconductor films and at gate dielectric/organic semiconductor interface. To achieve low voltage-operating OFETs, there have been many attempts to obtain high capacitance in gate dielectrics by reducing the thickness of dielectrics or increasing the dielectric constant of dielectrics. It is known that the substantial insulator thickness about over 300 nm is required to reduce gate leakage currents to acceptable levels for typical polymer such as polyimides and poly(4-vinyl phenol)s, therefore it is hard to use ultrathin polymer gate dielectrics, which is necessary for the high capacitance, in OFETs. In this study we investigated the possibility of application of ultrathin polymer gate dielectrics to OFETs with typical polymer dielectrics such as polyimide or poly(4-vinyl phenol). J-E and C-V characteristics of typical polymers were observed with thickness of dielectrics. Low- operating-voltage (~3 V) pentacene FETs can be realized with ultrathin typical polymer gate dielectrics (thickness~10 nm). The extracted mobility in saturation regime and on/off ratio were 0.3 cm2/Vs and 106, respectively. |
