Solar cell

1. A solar cell, comprising:

a semiconductor substrate;

a tunneling layer on one surface of the semiconductor substrate;

a first conductive type region on the tunneling layer, the first conductive type region having a first conductive type;

a second conductive type region on the tunneling layer, the second conductive type region having a second conductive type;

a first electrode and a second electrode, the first electrode connected to the first conductive type region and the second electrode connected to the second conductive type region; and

a barrier region on the tunneling layer, wherein the barrier region is disposed at at least a part of a boundary portion between the first conductive type region and the second conductive type region,

wherein the tunneling layer comprises a first portion and a second portion,

the first portion is disposed to correspond to at least a part of the first and second conductive type regions and has a first thickness,

the second portion is disposed to correspond to the boundary portion between the first conductive type region and the second conductive type region, and

the second portion has a second thickness greater than the first thickness,

wherein the second portion is disposed to correspond to at least a part of the barrier region,

wherein a step or a gap is formed between a first surface of the barrier region on the second portion and a first surface of the first and second conductive type regions on the first portion,

wherein the tunneling layer is disposed between the semiconductor substrate and the first and second conductive type regions,

wherein a width of the second portion is the same with a width of the barrier region,

wherein the second portion comprises at least one of silicon oxide, silicon nitride, silicon carbide, and aluminum oxide, and

wherein the barrier region includes an intrinsic semiconductor.

2. The solar cell according to claim 1 , wherein the first surface of the first and second conductive type regions is protruded toward the semiconductor substrate more than the first surface of the barrier region.

3. The solar cell according to claim 2 , wherein a second surface of the barrier region opposite to the first surface of the barrier region is flush with a second surface of the first and second conductive type regions opposite to the first surface of the first and second conductive type regions, or

wherein a step or a gap is formed between the second surface of the barrier region and the second surface of the first and second conductive type regions.

4. The solar cell according to claim 1 , wherein side surfaces of the barrier region are flush with side surfaces of the second portion.

5. The solar cell according to claim 1 , wherein side surfaces of the barrier region are misaligned with side surfaces of the second portion.

6. The solar cell according to claim 5 , where a part of the second portion overlaps with at least one of the first and second conductive type regions.

7. The solar cell according to claim 6 , wherein the semiconductor substrate comprises a base region having the second conductive type,

the second portion protrudes toward the first conductive type region, and

the second portion includes a first section between the semiconductor substrate and the barrier region, and a second section between the semiconductor substrate and the first conductive type region.

8. The solar cell according to claim 6 , wherein a width of a section of the second portion between the barrier region and the semiconductor substrate is about 50% or more of a width of the barrier region.

9. The solar cell according to claim 7 , wherein the first conductive type is a p-type, and the second conductive type is an n-type.

10. The solar cell according to claim 1 , wherein the boundary portion between the first conductive type region and the second conductive type region comprises a contact boundary where the first conductive type region is in contact with the second conductive type region.

11. The solar cell according to claim 1 , wherein a contact surface between the first conductive type region and the second conductive type region is positioned on the second portion.

12. The solar cell according to claim 1 , wherein the boundary portion between the first conductive type region and the second conductive type region comprises:

a first boundary where the barrier region is interposed between the first conductive type region and the second conductive type region; and

a second boundary where the first conductive type region is in contact with the second conductive type region.

13. The solar cell according to claim 1 , wherein the first portion comprises at least one of silicon oxide, silicon nitride, silicon carbide, and aluminum oxide.

14. The solar cell according to claim 1 , further comprising:

an insulating layer on the first conductive type region and the second conductive type region; and

a passivation layer on the other surface of the semiconductor substrate,

wherein the second thickness is lesser than each of thicknesses of the first and second conductive type regions, the insulating layer, and the passivation layer.

15. The solar cell according to claim 1 , wherein the first thickness is in a range from about 0.5 nm to about 5 nm, and

the second thickness is in a range from about 2 nm to about 100 nm.

16. The solar cell according to claim 1 , wherein the barrier region and the second portion of the tunneling layer contacts at the first surface of the barrier region.