Optical second harmonic generation measurements for investigating electron injection into a pentacene field effect transistor with Au source and drain electrodes

The pentacene field effect transistors (FETs)' operation for the injection carrier was revealed by means of the drain current–elapsed time (Ids–t) and optical second harmonic generation (SHG) measurements. The charge carriers forming the conducting channel of pentacene FETs were mainly holes injected from the Au source electrode. Carrier injection from source and drain electrodes was followed by the carrier trapping, and the SHG signal modulated by the change in the electric field distribution between Au the source and drain electrodes was shown. In particular, at the off state of the FET, electron injection and succeeding trapping were suggested. Furthermore, hole injection assisted by trapped electrons was also suggested.