Patent ID: 8530897

Claim:
A display device comprising: a driver circuit comprising an inverter circuit including a first thin film transistor and a second thin film transistor, the first thin film transistor and the second thin film transistor each comprising: a microcrystalline semiconductor layer on and in contact with a gate insulating layer; a layer including an amorphous semiconductor and a microcrystalline semiconductor having a conical or pyramidal shape or a projecting shape on and in contact with the microcrystalline semiconductor layer, the layer having a flat top surface; and a pair of impurity semiconductor layers over the layer including the amorphous semiconductor and the microcrystalline semiconductor, wherein the first thin film transistor and the second thin film transistor are enhancement type thin film transistors and have a same conductivity type, wherein the first thin film transistor comprises a gate terminal and a first terminal, which are electrically connected to a first power supply line, wherein the second thin film transistor comprises a gate terminal configured to be supplied with an input signal, a first terminal electrically connected to a second terminal of the first thin film transistor, and a second terminal electrically connected to a second power supply line, and wherein potential of the first power supply line is higher than potential of the second power supply line.