Excellent Current Drivability and Environmental Stability in Room-Temperature-Fabricated Pentacene-Based Organic Field-Effect Transistors With ${\rm HfO}_{2}$ Gate Insulators

Low-voltage-operating pentacene-based organic field-effect transistors (OFETs) with HfO 2 gate insulators have been fabricated at room temperature. Despite its thin capacitance equivalent thickness of 3.6 nm, the room-temperature-processed HfO2 gate insulator shows a low leakage current density of 1.2×10 -7 A/cm 2 at a gate voltage of -2 V. Pentacene films grown on the HfO2 gate insulators have a large grain size and a highly ordered molecular structure due to the appropriate surface properties of the HfO 2 gate insulators. The as-fabricated pentacene-based OFET (W/L=1300 μm/100 μm) with a HfO 2 gate insulator has a low subthreshold swing of 0.13 V/decade, a large ON/OFF current ratio of 9.8×10 4 , and a high hole mobility of 0.34 cm 2 V -1 s -1 at an operating voltage of -2 V. Furthermore, the environmental stability in the room-temperature-fabricated pentacene-based OFETs with HfO2 gate insulators was investigated.