Amorphous oxide semiconductors are of potential interest in the display industry due to their high carrier mobility, transparency at visible wavelengths and excellent operational stability. In this dissertation, n-channel zinc-tin oxide thin-film transistors are fabricated based on a solution-based deposition approach, which allows low fabrication cost and high throughput. The effects of device configuration and process conditions on transistor performance are investigated, and circuit applications including inverters, amplifiers, and ring oscillators are demonstrated. Charge transport in the zinc-tin oxide field-effect transistors is also investigated. A transition from thermally-activated to band-like transport is observed with increasing carrier concentration in high mobility samples, which agrees well with the key predictions of the multiple trap and release model and also Mott’s mobility edge model. In addition, velocity distribution of charge carriers is studied with a time-resolved technique. This provides a more detailed picture of charge transport in field-effect transistors. P-channel organic semiconductor field-effect transistors are also investigated with a view to combine them with n-channel amorphous oxide transistors to create a hybrid organic-inorganic complementary technology. / text