Reducing off-state leakage in semiconductor devices

An integrated circuit device comprising:

• a nanowire comprising a first semiconductor material having a first band gap between a conduction band and a valence band of the first semiconductor material;
• an insulation structure below the nanowire;
• a gate structure completely wrapped around the nanowire, that gate structure including a gate dielectric structure having a portion on the nanowire and a portion on the insulation structure, wherein the portion of the gate dielectric structure on the insulation structure is continuous along the insulation structure beneath the nanowire, the gate structure further including a gate electrode structure on the gate dielectric structure;
• and
• a source region and a drain region, the nanowire between the source region and the drain region, wherein at least one of the source region and the drain region comprises a second semiconductor material having a second band gap between a conduction band and a valence band of the second semiconductor material, the second band gap less than the first band gap of the nanowire, and wherein the insulation structure extends vertically beneath the source region and the drain region.

An integrated circuit device comprising:

• a body having a top surface and a bottom surface opposite the top surface, the body comprising a first semiconductor material having a first band gap between a conduction band and a valence band of the first semiconductor material;
• an insulation structure below the body;
• a gate structure including a gate dielectric structure having a portion on the body and a portion on the insulation structure, wherein the portion of the gate dielectric structure on the insulation structure is continuous along the insulation structure beneath the body, the gate structure further including a gate electrode structure on the gate dielectric structure, wherein the gate structure is completely wrapped around a channel region of the body;
• and
• a source region and a drain region, the body between the source region and the drain region, wherein at least one of the source region and the drain region comprises a second semiconductor material having a second band gap between a conduction band and a valence band of the second semiconductor material, the second band gap less than the first band gap of the body;
• wherein the first semiconductor material is indium phosphide which includes indium and phosphorus and the second semiconductor material is indium gallium arsenide which includes indium, gallium, and arsenic, or the first semiconductor material is aluminum antimonide which includes aluminum and antimony and the second semiconductor material includes germanium, and wherein the insulation structure extends vertically beneath the source region and the drain region.