Thin film transistor and method for manufacturing the same

A method for manufacturing a top-gate thin film transistor, comprising:

• a step of forming a source electrode and a drain electrode on an insulated substrate;
• a step of forming a first and a second impurity-doped semiconductor layers containing one of a first and a second electrically conductive impurities and electrically connected to the source electrode and drain electrode respectively;
• a step of forming a first semiconductor layer including microcrystalline semiconductor regions and an amorphous semiconductor region covering at least the first and the second impurity-doped semiconductor layers;
• a step of forming a second semiconductor layer of a microcrystalline semiconductor on the first semiconductor layer;
• and
• a step of forming a gate insulation film on the second semiconductor layer;
• wherein the step of forming the first semiconductor layer includes:
• a process of growing a microcrystalline semiconductor region having a same crystal structure as of the first and the second impurity-doped semiconductor layers on each of the first and the second impurity-doped semiconductor layers;
• and growing an amorphous semiconductor region on the source electrode and on the drain electrode.