Semiconductor device having a varying thickness nanowire channel and method for fabricating the same

A transistor, comprising:

• a drain;
• a source;
• a gate electrode;
• a first nanowire between the source and drain;
• and
• a gate spacer formed on opposite sidewalls of the gate electrode, wherein
• the gate spacer includes a hole therein,
• the first nanowire extends through the hole in the gate spacer to contact the source and drain,
• the first nanowire has a first section with a first thickness and a second section with a second thickness different from the first thickness, wherein the second section is between the first section and at least one of the source or drain, the first nanowire to include a channel when a voltage is applied to the gate electrode,
• the gate electrode surrounds a periphery of the first section, and
• the gate spacer surrounds a periphery of the second section.