Performance improvement of organic thin-film transistors by electrode/pentacene interface treatment using a hydrogen plasma

Pentacene-based organic thin-film transistors (TFTs) have been fabricated with and without treatment by hydrogen (H-2) plasma at the interface between the electrode and the pentacene surface. Processing with a H-2 plasma was carried out in a plasma-enhanced chemical vapor deposition with varying treatment times. The interface treatment by H-2 plasma resulted in improved device electrical properties. Removal of oxygen from the pentacene surface occurs due to slight etching by the plasma. Sufficient flux density Of the H-2 plasma leads to full pentacene-surface coverage by rearranging the hydrogen with carbon instead of oxygen. Atomic force microscopy profiles reveal the morphology changes of the pentacene surface after treatment, and secondary ion mass spectrometry shows the change via compositional depth profiles indicating H-2, O-2, and C-H binding. Hydrogen treatment, therefore, appears to modify the interface by removing the surface oxygen layer, resulting in better performance of the organic TFT.