Hole mobility in organic single crystal field effect transistors

Summary form only given. Transport in organic molecular crystals (OMCs) is a topic of intense fundamental study. To access the transport properties of OMCs we make use of a field-effect device structure to accumulate a large sheet carrier density of holes at the crystal surface and fill trap states. Single crystal organic FETs were fabricated for this purpose. Using either a 2 or 4 terminal configuration, hole mobility greater than 10 cm/sup 2//Vs for rubrene and 1 cm/sup 2//Vs for tetracene and pentacene has been measured. The 4 terminal measurement allows the contact effects to be separated from the channel properties. We present the temperature dependence of the electrical characteristics and discuss the transport of the field-accumulated charge near the surface. Additionally, we report on complementary space-charge-limited-current measurements that reflect the bulk properties of the OMCs.