In this study, we present a new method named seed-induced lateral crystallization (SILC), wherein the Ni that is deposited on amorphous silicon (a-Si) is removed prior to crystallization. The newly developed polycrystalline silicon (poly-Si) thin-film transistor (TFT) exhibits a field effect mobility of 63 cm 2 /V-s, leakage current of 7.9 × 10 −11 A, slope of 0.8 V/dec, I on of 2.8 × 10 −4 A at V D = 10 V, and V TH of 5.5 V. The leakage current has been reduced by an order of magnitude as compared with conventional metal-induced lateral crystallized (MILC) poly-Si TFTs, in which Ni is removed after the crystallization. In order to materials analysis, Raman scattering spectroscopy and field emission scanning electron microscopy (FESEM) was used. Since a batch process is possible in MILC technology, it is more advantageous than the excimer laser annealing (ELA) technology for mass production of a large size display. Since SILC TFT shows a leakage current comparable to an ELA poly-Si TFT, its application to the mass production of AMOLED display is expected have a substantial impact on the industry. Active matrix organic light emitting diode (AMOLED) technology has many advantages over liquid crystal display (LCD) in terms of display functions and is, therefore, beginning to replace LCD technology. Because AMOLED requires low-temperature polycrystalline silicon (poly-Si) thin-film transistors (TFTs), for which no industrial technology is yet known, very limited and only small size display is available so far. The excimer laser annealing (ELA) is a typical low-temperature crystallization method but suffers from two critical problems, which have not yet been overcome in terms of cost for mass production. One is the inevitable scan overlap, which leads to crystal non-uniformity; the other is the resulting surface roughness, which stems from a liquid-solid phase transformation.

The major problem of metal-induced crystallized (MIC) polycrystalline Si (poly-Si) thin-film transistors (TFTs) is metal contamination, from Ni and NiSi 2 . Many attempts have been made to address this problem, however, they all involve complicated processes. In this study, we investigate a new crystallization method, that is, seed-induced crystallization, using Ni silicide seed. There are no additional mask processes, deposition and/or etching processes. The poly-Si thin films crystallized by SIC are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), atomic force microscopy (AFM), micro-Raman scattering spectroscopy and the electrical properties are obtained from I D -V G transfer curve measurements. The results show that, lower Ni contamination, smoother surface and larger grain size are achieved in the SIC produced poly-Si thin films compared to those of the MIC poly-Si thin films. The p-channel SIC poly-Si TFTs, show a mobility of 62.08 cm 2 /V • s, minimum leakage current of 1.17 × 10 −10 A at V D = 10 V, subthreshold slope of 0.7 V/dec and maximum on/off ratio of 1.7 × 10 6 , all of which lead to a high-performance device which exceeds conventional MIC poly-Si TFTs.

The authors investigated the field emission characteristics of printed carbon nanotubes (CNTs) on KOVAR substrates with micro- and nanosize line patterns. Microsized line patterns were fabricated using photolithography techniques followed by an inductive coupled plasma-reactive ion etching process, and laser interference lithography techniques were used to fabricate uniform nanosized patterns over a relatively large area. CNTs were printed on the patterned substrate using a screen printing method. The field emission characteristics of each patterned substrate were compared to those of a nonpatterned substrate. Results revealed that varying the pattern size has an influence on the field emission characteristics. The reduction of the pattern size results in an increase in the total surface area. This surface patterning is found to provide additional areas for CNTs to adhere to the substrates, which, in turn, results in better adhesion of CNTs. As the size of the pattern is reduced, the field emission properties are improved. Specifically, substrates with nanosized patterns exhibited both the lowest turn-on field and the highest field enhancement factor (β).

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