Thin-film transistor, producing method thereof, array substrate, and display device

Provided is a method for producing a thin-film transistor. The method comprises: a step of depositing a crystallized precursor, wherein a chemical vapor deposition (CVD) process is used and a carbon-containing gas and a silicon-containing gas are used as a reaction source in the CVD process; a crystallizing step; a step of forming an active layer; a step of forming a gate insulated layer and a gate electrode; and a step of forming a source electrode and a drain electrode. The method for producing the thin-film transistor may increase the forbidden bandwidth of the active layer so as to further reduce the leakage current of the low temperature poly-silicon thin-film transistor, the visible light absorption coefficient of the low temperature poly silicon, and the photoinduced leakage current generated by a backlight. In addition, the method for producing the thin-film transistor is suitable for a conventional poly-silicon thin-film transistor production line, prevents an increase in the number of photomask times and a change in production equipment, and is easy and convenient to operate. The invention also provides a thin-film transistor, an array substrate, and a display device.