Semiconductor device and method of manufacturing same

A semiconductor device comprising:

• a substrate;
• a gate electrode formed above the substrate;
• a gate insulating film formed under the gate electrode;
• a channel layer formed under the gate insulating film by using a channel layer material, the channel layer material being a material different from that of the substrate;
• a source region and a drain region formed in the substrate so as to interpose the channel layer therebetween in a channel direction;
• and
• a source extension layer formed in the substrate between the channel layer and the source region so as to be abutted on a source-side end portion of the channel layer, the source extension layer forming a heterointerface with the channel layer, and the heterointerface being a tunnel channel for carries and extending in a first direction parallel to a surface of the substrate, the surface of the substrate being opposed to a lower surface of the gate insulating film via the channel layer,
• wherein the material of the substrate and the channel layer material respectively have first and second band gaps to cause the carriers to flow in a second direction perpendicular to the surface of the substrate through the heterointerface.