High reliability of vanadyl-phthalocyanine thin-film transistors using silicon nitride gate insulator

Abstract

The reliability of vanadyl-phthalocyanine (VOPc) thin film transistors (TFTs) with silicon nitride (SiNx) gate insulator was investigated under bias stress conditions. The shift of threshold voltage in ambient air, in vacuum and at high temperature was discussed. The initial field-effect mobility and threshold voltage were 1.2cm2/Vs and −4.22V, respectively. After a gate bias stress of −20V for 10,000s in ambient air, the threshold voltage showed a small shift of less than 0.6V. In vacuum at high temperature, the shifts of threshold voltage were also below 1V and current change of devices under the same bias condition was negligible. The excellent reliability was attributed to the reduction of interface defect states between VOPc film and SiNx gate insulator. These results show that VOPc TFTs using SiNx insulator hold a great promise of application in active-matrix organic light emitting displays.