Display device

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 a microcrystalline semiconductor having a conical or pyramidal shape or a projecting shape on and in contact with the microcrystalline semiconductor layer;
• and
• a pair of impurity semiconductor layers over the gate insulating layer,
• wherein the first thin film transistor and the second thin film transistor are enhancement type thin film transistors and have a same conductivity type, and
• wherein the pair of impurity semiconductor layers are on and in contact with the gate insulating layer.

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 insulting layer;
• a layer including a microcrystalline semiconductor having a conical or pyramidal shape or a projecting shape on and in contact with the microcrystalline semiconductor layer;
• and
• a pair of impurity semiconductor layers over the gate insulating layer,
• wherein the first thin film transistor and the second thin film transistor are enhancement type thin film transistors and have a same conductivity type, and
• wherein part of the layer including the microcrystalline semiconductor having a conical or pyramidal shape or a projecting shape is in contact with an insulating layer provided over the pair of impurity semiconductor layers.