**1. Introduction**

The development of electronic and optoelectronic devices attending the increasing demand of new features like high-resolution, fast response, transparency and flexibility has motivated the pursuit of circuits using new active materials and/or new processing technologies. In this sense, semiconducting metal oxides (SMOs) as zinc oxide (ZnO) [1–9] and related compounds like aluminumdoped zinc oxide (AZO) [10–13], indium zinc oxide (IZO) [14, 15] and indium gallium zinc oxide (IGZO) [16, 17] are promising materials for flexible, transparent and high-performance electronics.

SMOs are particularly interesting to be used as the active layer of thin-film transistors (TFTs), which constitute the basic electronic device for drive circuits of active-matrix displays (AMDs)

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and more sophisticated logic circuits which can be used in memories, microcontrollers and processors. Recently, the manufacture of metal oxide thin films using organic precursor solutions or nanoparticle suspensions became widespread [1–10], permitting the use of low-cost and nonsophisticated deposition techniques as spin coating, ink-jet printing and spray pyrolysis [18–21]. These techniques produce very uniform and homogeneous nanoscaled films, with high control of thickness and of other physical properties. This chapter aims to describe briefly the manufacturing processes of TFTs using solution-processed metal oxides as the semiconducting active layer, focusing on the electrical characterization and the study of the electrical properties relevant to the evaluation of device performance.
