Determination of carrier mobility of semiconductor layer in organic metal-insulator-semiconductor diodes by displacement current and electric-field-induced optical second-harmonic generation measurements

Abstract

A novel method for determining carrier mobility of semiconductor layer in thin-film organic metal-insulator-semiconductor (MIS) diodes is proposed, where displacement current measurement (DCM) is used in combination with electric-field-induced optical second-harmonic generation (EFISHG) measurement. EFISHG signals generated from the semiconductor layer probe the electric field caused by carriers moving in the semiconductor layer of MIS diodes. On the other hand, DCM signals generated in accordance with the time derivative of induced charge on metal electrode well identify the transit time of carriers across the semiconductor layer. By using Au/pentacene/polyimide (PI)/indium-tin-oxide (ITO) diodes, we experimentally determined the carrier mobility of the pentacene layer. Results and analysis showed that step-voltage application to MIS diodes is suitable for the use of this proposed method.