A capacitor with large capacitance, a transistor with excellent electrical characteristics, a transistor with high on-state current, or a transistor with small parasitic capacitance is provided. A device includes a first insulating layer, a first conductive layer over the first insulating layer, a second insulating layer over the first insulating layer and the first conductive layer, and a capacitor over the first conductive layer. The second insulating layer includes an opening portion that reaches the first conductive layer and includes a narrowed upper portion. A lower electrode, an upper electrode, and a dielectric of the capacitor each include a portion positioned in the opening portion. The lower electrode includes a portion in contact with the top surface of the first conductive layer and a portion provided along the opening portion.

An example thin-film transistor includes a source, a drain, a gate, and a body of channel material disposed within the influence of the gate between the source and the drain. The body of channel material includes a metal oxide. The body of channel material forms a carrier channel between the source and the drain when sufficient voltage is applied to the gate. The source includes a body of source material that includes ruthenium and an oxide-stabilizing metal that has an oxide that has greater hydrogen stability than ruthenium oxide.

An example thin-film transistor includes a silicon-based substrate and a source and drain at the silicon-based substrate. The source and drain are spaced apart by a gap. The thin-film transistor further includes a nucleation layer in contact with at least the silicon-based substrate within the gap, and a body of channel material in contact with the nucleation layer. The channel material is nanocrystalline tin oxide (SnO.sub.2). The nucleation layer includes a nucleation element that may reduce thermally induced stress between the silicon-based substrate and the body of channel material. The nucleation element may also promote a preferred crystal orientation for the channel material.

An example thin-film transistor includes a source, a drain, a gate, and a body of channel material disposed within the influence of the gate between the source and the drain. The body of channel material includes a metal oxide. The body of channel material forms a carrier channel between the source and the drain when sufficient voltage is applied to the gate. The source includes a body of source material that includes ruthenium and an oxide-stabilizing metal that has an oxide that has greater hydrogen stability than ruthenium oxide.