Asymmetrical semiconductor nanowire field-effect transistor
An integrated circuit structure includes: a semiconductor nanowire extending in a length direction and including a body portion; a gate dielectric surrounding the body portion; a gate electrode insulated from the body portion by the gate dielectric; a semiconductor source portion adjacent to a first side of the body portion; and a semiconductor drain portion adjacent to a second side of the body portion opposite the first side, the narrowest dimension of the second side of the body portion being smaller than the narrowest dimension of the first side. In an embodiment, the nanowire has a conical tapering. In an embodiment, the gate electrode extends along the body portion in the length direction to the source portion, but not to the drain portion. In an embodiment, the drain portion at the second side of the body portion has a lower dopant concentration than the source portion at the first side.
1. An integrated circuit (IC) structure comprising:
a semiconductor nanowire extending in a length direction and including a body portion;
a gate dielectric surrounding the body portion;
a gate electrode on the gate dielectric;
a semiconductor source portion adjacent to a first side of the body portion; and
a semiconductor drain portion adjacent to a second side of the body portion, the second side being opposite the first side, and the narrowest dimension of the second side of the body portion being at least one nanometer (nm) smaller than the narrowest dimension of the first side of the body portion, wherein one of the semiconductor drain portion or the semiconductor source portion is vertically over the other of the semiconductor drain portion or the semiconductor source portion, wherein the body portion is tapered from the semiconductor source portion to the semiconductor drain portion, and wherein the gate electrode extends along the body portion in the length direction to the source portion, but not to the drain portion.
2. The IC structure of claim 1 , wherein the narrowest dimension of the second side of the body portion is at most half the narrowest dimension of the first side.
3. The IC structure of claim 1 , wherein the narrowest dimension of the second side of the body portion is at most four nm, and the narrowest dimension of the first side is at least six nm.
4. The IC structure of claim 1 , wherein the narrowest dimension of the second side of the body portion is at most three nm, and the narrowest dimension of the first side is at least eight nm.
5. The IC structure of claim 1 , wherein the narrowest dimension of the second side of the body portion is in the range of two to eight nm smaller than the narrowest dimension of the first side.
6. The IC structure of claim 1 , wherein the drain portion at the second side of the body portion has a lower dopant concentration than the source portion at the first side of the body portion.
7. The IC structure of claim 1 , wherein the length direction is a vertical direction relative to an underlying substrate.
8. The IC structure of claim 1 , wherein the nanowire has a tapered cross-section in the length direction.
9. The IC structure of claim 8 , wherein the nanowire has a conical tapering.
10. The IC structure of claim 8 , wherein the nanowire has a convex tapering.
11. The IC structure of claim 8 , wherein the nanowire has a concave tapering.
12. The IC structure of claim 1 , wherein the bandgap of semiconductor material in the semiconductor nanowire is less than the bandgap of silicon.
13. The IC structure of claim 1 , wherein the nanowire comprises germanium.
14. The IC structure of claim 1 , wherein one or more of the body portion, the source portion, and the drain portion include or includes dopant in the form of impurities.
15. A computing system comprising the IC structure of claim 1 .
16. An integrated circuit (IC) structure comprising:
a semiconductor nanowire extending vertically and including a tapered body portion, the tapered body portion including germanium;
a gate dielectric surrounding the tapered body portion;
a gate electrode on the gate dielectric;
a semiconductor source portion adjacent to a first side of the tapered body portion, the first side being a top or a bottom of the tapered body portion; and
a semiconductor drain portion adjacent to a second side of the tapered body portion, the second side being the other of the top or the bottom of the tapered body portion, and the narrowest dimension of the second side of the tapered body portion being smaller than the narrowest dimension of the first side of the tapered body portion, wherein one of the semiconductor drain portion or the semiconductor source portion is vertically over the other of the semiconductor drain portion or the semiconductor source portion, wherein the tapered body portion is tapered from the semiconductor source portion to the semiconductor drain portion, and wherein the gate electrode extends along the tapered body portion in the vertical direction to the source portion, but not to the drain portion.
17. An integrated circuit (IC) structure comprising:
a semiconductor nanowire extending in a length direction and including a body portion;
a gate dielectric surrounding the body portion;
a gate electrode on the gate dielectric;
a semiconductor source portion adjacent to a first side of the body portion; and
a semiconductor drain portion adjacent to a second side of the body portion, the second side being opposite the first side, and the narrowest dimension of the second side of the body portion being at least one nanometer (nm) smaller than the narrowest dimension of the first side of the body portion, wherein one of the semiconductor drain portion or the semiconductor source portion is vertically over the other of the semiconductor drain portion or the semiconductor source portion, wherein the gate electrode extends along the body portion in the length direction to the source portion, but not to the drain portion.