Abstract: Provided is a semiconductor device which can operate stably even in the case where a transistor thereof is a depletion transistor. The semiconductor device includes a first transistor for supplying a first potential to a first wiring, a second transistor for supplying a second potential to the first wiring, a third transistor for supplying a third potential at which the first transistor is turned on to a gate of the first transistor and stopping supplying the third potential, a fourth transistor for supplying the second potential to the gate of the first transistor, and a first circuit for generating a second signal obtained by offsetting a first signal. The second signal is input to a gate of the fourth transistor. The potential of a low level of the second signal is lower than the second potential.

Abstract: TFTs of peripheral logic circuits and TFTs of an active matrix circuit (pixel circuit) are formed on a single substrate by using a crystalline silicon film. The crystalline silicon film is obtained by introducing a catalyst element, such as nickel, for accelerating crystallization into an amorphous silicon film and heating it. In doing so, the catalyst element is introduced into regions for the peripheral logic circuits in a non-selective manner, and is selectively introduced into regions for the active matrix circuit. As a result, vertical crystal growth and lateral crystal growth are effected in the former regions and the latter regions, respectively. Particularly in the latter regions, the off-current and its variation can be reduced.