Copper phthalocyanine-based organic thin-film transistors (OTFTs) with zirconium oxide (ZrO2) as gate dielectric have been\nfabricated on glass substrates. The gate dielectric is annealed in N2 at different durations (5, 15, 40, and 60 min) to investigate the\neffects of annealing time on the electrical properties of the OTFTs. Experimental results show that the longer the annealing time for\nthe OTFT, the better the performance. Among the devices studied, OTFTs with gate dielectric annealed at 350?C in N2 for 60 min\nexhibit the best device performance. They have a small threshold voltage of -0.58 V, a low subthreshold slope of 0.8 V/decade,\nand a low off-state current of 0.73 nA. These characteristics demonstrate that the fabricated device is suitable for low-voltage and\nlow-power operations. When compared with the TFT samples annealed for 5 min, the ones annealed for 60 min have 20% higher\nmobility and nearly two times smaller the subthreshold slope and off-state current. The extended annealing can effectively reduce\nthe defects in the high-k film and produces a better insulator/organic interface. This results in lower amount of carrier scattering\nand larger CuPc grains for carrier transport.
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