Nanocrystalline silicon (nc-Si) thin film transistors (TFTs) are well suited for circuit applications that require moderate device\r\nperformance and low-temperature CMOS-compatible processing below 250�°C. Basic logic gate circuits fabricated using ambipolar\r\nnc-Si TFTs alone are presented and shown to operatewith correct outputs at frequencies of up to 100 kHz. Ring oscillators consisting\r\nof nc-Si TFT-based inverters are also shown to operate at above 20 kHz with a supply voltage of 5V, corresponding to a propagation\r\ndelay of <10 ??s/stage. These are the fastest circuits formed out of nanocrystalline silicon TFTs to date. The effect of bias stress\r\ndegradation of TFTs on oscillation frequency is also explored, and relatively stable operation is shown with supply voltages >5V\r\nfor several hours.
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