Characteristics of pentacene-based thin-film transistors

Pentacene was used as an active layer of organic thin-film transistors (TFTs) by depositing with the vacuum thermal evaporation. It is revealed that the deposition rate of pentacene may have critical effects on the electrical properties of pentacene-based TFTs. For the device fabrication, pentacene layers were deposited at a rate of 0.5, 1.0 and 2.5 Å/s. Upon the investigations, TFT with the pentacene layer deposited at a rate of 2.5 Å/s showed the most superior properties. The field-effect mobility of 0.16 cm2/V s, and the on/off current ratio of 105 were obtained at a drain voltage of −30 V. To study the correlation between the deposition rate and the device performance, the capacitance properties were also measured in the metal/insulator/organic semiconductor (MIS) structure device by employing the capacitance–voltage (C–V) measurements. The lowest capacitance value was observed in the device with the pentacene layer deposited at a rate of 2.5 Å/s.