| Summary: | Sol-gel processed SnO<sub>2</sub> thin-film transistors (TFTs) were fabricated on SiO<sub>2</sub>/p<sub>+</sub> Si substrates. The SnO<sub>2</sub> active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO<sub>2</sub> active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (<i>SS</i>), and increased threshold voltage (<i>V<sub>th</sub></i>), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO<sub>2</sub> TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm<sup>2</sup>/Vs, an <i>SS</i> of 1.99, an <i>I<sub>on</sub></i>/<i>I<sub>off</sub></i> value of ~4.0 × 10<sup>7</sup>, and showed enhancement mode operation and positive <i>V<sub>th</sub></i>, equal to 9.83 V.
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