Semiconductor device

1. A semiconductor device comprising:

a semiconductor column including a first conductive region of first conductivity type, a second conductive region of second conductivity type, an intrinsic region disposed between the first conductive region and the second conductive region, and a barrier region of the first conductivity type disposed between the intrinsic region and the second conductive region;

a gate electrode disposed only to cover the intrinsic region with respect to a side view of the semiconductor device; and

a gate insulating layer disposed between the gate electrode and the intrinsic region,

wherein the semiconductor device is configured to operate a switchable 1-transistor memory according to a gate voltage applied to a gate and a drain voltage applied to a drain;

wherein the semiconductor column is forward biased,

wherein the semiconductor device shows a hysteresis in a drain current with respect to the gate voltage,

wherein the first conductivity type of the first conductive region is n-type,

wherein the second conductivity type is p-type,

wherein the first conductive region provides a source, and the second conductive region provides the drain.

2. The semiconductor device as set forth in claim 1 , wherein:

the semiconductor column extends vertically on a substrate.

3. The semiconductor device as set forth in claim 1 , wherein:

when the semiconductor device operates a nonvolatile memory,

to write a first logic state, a first gate voltage is applied to the gate electrode and a first drain voltage is applied to the second conductive region,

to hold the first logic state, a second gate voltage is applied to the gate electrode and a second drain voltage is applied to the second conductive region,

to read the first logic state, the second gate voltage is applied to the gate electrode and the first drain voltage is applied to the second conductive region,

to write a second logic state, a third gate voltage is applied to the gate electrode and the first drain voltage is applied to the second conductive region,

to hold the second logic state, a second gate voltage is applied to the gate electrode and the second drain voltage is applied to the second conductive region, and

to read the second logic state, the second gate voltage is applied to the gate electrode and the first drain voltage is applied to the first conductive region.

4. The semiconductor device as set forth in claim 3 , wherein:

the first gate voltage is between −0.25V and −1V,

the second gate voltage is between −0.1V and 0.1V,

the third gate voltage is between 0.25V and 1V,

the first drain voltage is between 0.5V and 1.5V, and

the second drain voltage is 0V.

5. The semiconductor device as set forth in claim 1 , wherein:

when the semiconductor device operates as a switch,

to switch to a first state, a positive first gate pulse is applied to the gate electrode while a first drain voltage is applied to the second conductive region, and

to switch to a second state from the first state, a negative second gate pulse is applied to the gate electrode while the first drain voltage is applied to the second conductive region,

the first state is maintained after the positive first gate pulse is removed,

the second state is maintained after the negative second gate pulse is removed.

6. The semiconductor device as set forth in claim 3 , wherein:

the first gate voltage is a negative voltage,

the second gate voltage is a positive voltage, and

the drain voltage is between 0.5V and 1.5V.

7. The semiconductor device as set forth in claim 2 , wherein:

the substrate includes an active region and a device isolation layer,

the first conductive region is disposed in contact with the active region, and

the active region is doped with impurities of the first conductive type.

8. The semiconductor device as set forth in claim 2 , further comprising:

a source line disposed on the substrate,

wherein:

the first conductive region is disposed in contact with the source line, and

the source line includes silicon doped with impurities of the first conductivity type.

9. The semiconductor device as set forth in claim 2 , wherein:

the first conductive region, the intrinsic region, the barrier region, and the second conductive region are sequentially disposed along the semiconductor column as proceeding from a bottom surface to a top surface.

10. The semiconductor device as set forth in claim 2 , wherein:

the second conductive region, the barrier region, the intrinsic region, and the first conductive region are sequentially disposed along the semiconductor column as processing from a bottom surface to a top surface.

11. The semiconductor device as set forth in claim 2 , further comprising:

a ring-shaped residual oxide layer disposed to cover the semiconductor column on a bottom surface of the semiconductor column.

12. A semiconductor device comprising:

a semiconductor column including a first conductive region of first conductivity type, a second conductive region of second conductivity type, an intrinsic region disposed between the first conductive region and the second conductive region, and a barrier region of the first conductivity type disposed between the intrinsic region and the second conductive region;

a gate electrode disposed only to cover the intrinsic region with respect to a side view of the semiconductor device; and

a gate insulating layer disposed between the gate electrode and the intrinsic region,

wherein the semiconductor device is configured to operate a switchable 1-transistor memory according to a gate voltage applied to a gate and a drain voltage applied to a drain,

wherein the semiconductor column is forward biased,

wherein the semiconductor device shows a hysteresis in a drain current with respect to the gate voltage,

wherein the semiconductor column extends vertically on a substrate,

wherein the first conductivity type of the first conductive region is p-type,

wherein the second conductivity type is n-type, and

the first conductive region provides a drain, and the second conductive region provides a source.