Performance Improvement in single-gate organic transistors with contacts at top and bottom: Additional p + region insertion near source and drain

Abstract

This research explores performance attributes of bottom gate top contact (BGTC) and bottom gate bottom contact (BGBC) organic thin film transistors (OTFT). To upgrade the performance characteristics, a region of 5nm with high concentration of carrier is tallied neighboring contacts. The drain current for BGTC is –18.6μA as compared to –5.1μA of BGBC transistor. Also, it is established that the innate attributes of BGTC are better than those of their counterparts, which is typically considered because of the inadequate contact attributes and mediocre semiconductor quality of BGBC OTFT. The analysis showed that upon varying the length of the channel ranging from 5μm to 40μm, there was a significant change in the drain current of BGTC and BGBC devices. For the same values of VGS and VDS (0V to –5V) where drain current in BGTC structure varied from –129.86μA to –13.69μA, whereas for their counterparts it ranged from –37.10μA to –3.76μA for channel length equal to 5μm and 40μm respectively. Also, with the varying doping strength ranging from 1012 cm–3 to 1016 cm–3 for BGBC device, drain current varied from –2.15μA to –18.52μA for BGTC whereas for BGBC it varied from –0.19μA to –7.09μA keeping VGS and VDS –5 V, yielding that upon varying the doping strength, where for BGTC ID changed by a factor of 8.6, the BGBC device showed a considerable change by a factor of 37.3. Likewise, mobility, threshold voltage, sub-threshold swing and transconductance also showing better performance with the P + insertion. These variations in the innate attributes are primarily due to the deficiency of carriers at the interface of source and channel, leading to a greater drop in the potential, which is more prominent for the bottom gate bottom contact devices.