FABRICATION OF A NORMALLY-ON ORGANIC THIN FILM TRANSISTOR FOR ACTIVE SENSOR CONSTRUCTION
Keywords:Organic thin-film transistor, OTFT fabrication, normally on OTFT, organic active pressure sensor
In organic active pressure sensor, a reduction in supply voltage of transistor is an effective way to decrease the power consumption. Up to now, for the development of pressure sensor based on normally-on OTFT (organic thin-film transistor), the OTFT where the conductive channel is formed without gate voltage supply, is still challenging. In this paper, we propose an approach to fabricate normally-on OTFT based on floating gate, photoactive gate dielectric layer and programming process using external UV source. After fabrication, measurements of OTFT characteristics, including transfer and output, were performed. Estimation of the critical parameters including the threshold voltage and field effect mobility was also described. Our fabricated OTFT shows good performance with a low threshold voltage of -4 V and high mobility of 0.893 cm2/Vs. Before programming, the OTFT is at normally-off state with drain current of 10-13 A at 0 V gate voltage. After programming, the OTFT changes to normally-on state with drain current of 10-6 A at 0 V gate voltage. OTFT fabrication is the essential step to construct an organic active pressure sensor in the future work.