WO3-doped LiF as gate dielectric for p-channel vertical organic field effect transistor application

We report low voltage operable p-channel vertical organic field effect transistors (VOFETs) using 5,5‴″-Dihexyl- 2,2′:5′,2″:5″,2‴:5‴,2‴′:5‴′,2‴″-sexithiophene (DH6T) as organic semiconductor and tungsten trioxide (WO3) doped lithium fluoride (LiF) nano-composite of various concentrations as high-k dielectric. Among the various doping concentrations of WO3, the 5 wt% WO3-doped LiF shows the best performance. The gate leakage was effectively reduced from 10−4 A/cm2 order to 10−6 A/cm2 by the addition of 5 wt% WO3-doped LiF as compare to 0 wt% WO3-doped LiF, resulted in higher drain current for this device. The best values of threshold voltage, mobility, on/off ratio, trans-conductance and sub-threshold slope for the devices made were estimated to be 0.85 V, 0.034 cm2/Vs, 105, 60 μS and 0.32 V/decade respectively.