| 초록 |
We investigated the bias-stress-induced charge trapping in organic field-effect transistors (OFETs). We revealed the role of polymer chain-ends of polymer gate-dielectrics (PGDs) as charge trap sites. The bias-stress stabilities of OFETs using PGD with various molecular weights (MW) are investigated. Under bias stress in ambient air, the drain current decay and the threshold voltage shift are increased as the MW of the PGD decreases. This MW effect is caused by the variation in the density of polymer chain-ends in the PGDs with MW: the free volumes at the polymer chain-ends act as charge trap sites, resulting in drain current decay during bias stress. The free volumes at polymer chain-ends are sufficiently large to allow the residence of water molecules, the presence of which significantly increases the density of charge-trap sites. We also demonstrated a novel strategy for separating out the contributions due to charge trapping events in the semiconductor and the gate-dielectric. |
