Patent ID: 8319219

Claim:
A light-emitting device comprising: a pixel portion; and a drive circuit for controlling operation of the pixel portion, wherein the pixel portion is provided with a pixel including a light-emitting element and a first TFT for controlling supply of current to the light-emitting element, wherein each of a second TFT included in the drive circuit and the first TFT comprises: a gate electrode over a substrate; a gate insulating film formed over the gate electrode; a first semiconductor film comprising semi-amorphous silicon over the gate electrode with the gate insulating film interposed therebetween; a pair of third semiconductor films comprising semi-amorphous silicon over the first semiconductor film; and a pair of second semiconductor films over the pair of third semiconductor films, respectively, wherein the pair of third semiconductor films are non-doped semiconductor films, wherein the pair of third semiconductor films and the pair of second semiconductor films have n-type conductive type, and wherein the pair of third semiconductor films has lower conductivity than the pair of second semiconductor films.