Self-Aligned Organic Field-Effect Transistors Using Back-Surface Exposure Method

Self-aligned organic field-effect transistors using the back-surface exposure method were investigated. Using the back-surface exposure method, source and drain electrodes were self-aligned to the gate electrode. The overlapping length of the gate-source and the gate-drain electrodes was as small as 0.8 µm. Excellent field-effect operation was obtained with small parasitic resistance, where the maximum field-effect mobility was 0.12 cm 2 /Vs. The on-off ratio was 10 4 , threshold voltage was -1.0 V, mutual conductance was 1.8 mS and subthreshold slope was 0.5 V/decade. Combined with capacitance measurement, the estimated cutoff frequency was 0.18 MHz.