US Patent 8143678 Thin film transistors having multi-layer channel

A transistor may include: a gate insulting layer; a gate electrode formed on the gate insulating layer; a channel layer formed on the gate insulating layer; and source and drain electrodes that contact the channel layer. The channel layer may have a double-layer structure, including upper and lower layers. The upper layer may have a carrier concentration lower than the lower layer. A method of manufacturing a transistor may include: forming a channel layer on a substrate; forming source and drain electrodes on the substrate; forming a gate insulating layer on the substrate; and forming a gate electrode on the gate insulating layer above the channel layer. A method of manufacturing a transistor may include: forming a gate electrode on a substrate; forming a gate insulating layer on the substrate; forming a channel layer on the gate insulating layer; and forming source and drain electrodes on the gate insulating layer.