High mobility, n-type transparent thin-film transistors ͑TTFTs͒ with a zinc indium oxide ͑ZIO͒ channel layer are reported. Such devices are highly transparent with ϳ85% optical transmission in the visible portion of the electromagnetic spectrum. ZIO TTFTs annealed at 600°C operate in depletion-mode with threshold voltages −20 to −10 V and turn-on voltages ϳ3 V less than the threshold voltage. These devices have excellent drain current saturation, peak incremental channel mobilities of 45-55 cm 2 V −1 s −1 , drain current onto off ratios of ϳ10 6 , and inverse subthreshold slopes of ϳ0.8 V / decade. In contrast, ZIO TTFTs annealed at 300°C typically operate in enhancement-mode with threshold voltages of 0-10 V and turn-on voltages 1-2 V less than the threshold voltage. These 300°C devices exhibit excellent drain-current saturation, peak incremental channel mobilities of 10-30 cm 2 V −1 s −1 , drain current onto off ratios of ϳ10 6 , and inverse subthreshold slopes of ϳ0.3 V / decade. ZIO TTFTs with the channel layer deposited near room temperature are also demonstrated. X-ray diffraction analysis indicates the channel layers of ZIO TTFTs to be amorphous for annealing temperatures up to 500°C and polycrystalline at 600°C. Low temperature processed ZIO is an example of a class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with ͑n −1͒d 10 ns 0 ͑n ജ 4͒ electronic configurations.

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Transparent electronics is an embryonic technology whose objective is the realization of invisible electronic circuits. We have recently reported the fabrication of a novel n-channel transparent thin-film transistor (TTFT). [1] This ZnO-based TTFT is highly transparent and exhibits electrical characteristics that appear to be suitable for implementation as a transparent select-transistor in each pixel of an active-matrix liquid-crystal display. Moreover, the processing technology used to fabricate this device is relatively simple and appears to be compatible with inexpensive glass substrate technology. The objective of the work reported herein is to summarize some of our recent TTFT electrical performance results. Materials, processing, and device structure details related to these devices appear in future publications.