Solar cell

1. A solar cell, comprising:

a semiconductor substrate;

a conductive region on or at the semiconductor substrate;

an electrode electrically connected to the conductive region;

a silicon oxynitride layer on a light incident surface of the semiconductor substrate; and

a first passivation layer on the silicon oxynitride layer,

wherein the silicon oxynitride layer comprises:

a first phase region having a first oxygen content and a first nitrogen content; and

a second phase region having a second oxygen content higher than the first oxygen content and a second nitrogen content lower than the first nitrogen content;

wherein the first phase region and the second phase region have a layered-structure sequentially stacked in a thickness direction of the silicon oxynitride layer,

wherein the first passivation layer comprises:

a silicon nitride layer formed to be contacted with the first phase region and positioned on the silicon oxynitride layer; and

a silicon carbonitride layer formed to be contacted with and positioned on the silicon nitride layer, and

wherein a carbon content of the silicon carbonitride layer is greater than a nitrogen content of the silicon carbonitride layer, based on atomic percent.

2. The solar cell of claim 1 , wherein each of the first phase region, and the second phase region has chemical formula of Si y (O x N 1-x ) 1-y , wherein x and y are greater than 0 and less than 1.

3. The solar cell of claim 1 , wherein the first phase region is in contact with the semiconductor substrate.

4. The solar cell of claim 1 , wherein the silicon oxynitride layer comprises approximately 1 to 20 at % of nitrogen.

5. The solar cell of claim 1 , wherein the silicon oxynitride layer comprises hydrogenated silicon oxynitride or silicon oxynitride including hydrogen.

6. The solar cell of claim 1 , wherein the silicon oxynitride layer and the first passivation layer are disposed so that an extinction coefficient increases in going away from the semiconductor substrate.

7. The solar cell of claim 6 , wherein the silicon oxynitride layer and the first passivation layer are arranged so that a refractive index increases in going away from the semiconductor substrate.

8. The solar cell of claim 1 , wherein a layer density deviation of the silicon oxynitride layer is greater than a layer density deviation of the first passivation layer.

9. The solar cell of claim 1 , wherein a thickness of the silicon carbonitride layer is the same as or less than a thickness of the silicon oxynitride layer or the silicon nitride layer.

10. The solar cell of claim 9 , wherein the thickness of the silicon oxynitride layer or the silicon nitride layer is in a range of approximately 10 to 100 nm, and

wherein the thickness of the silicon carbonitride layer is in a range of approximately 5 to 20 nm.

11. The solar cell of claim 1 , wherein the light incident surface with which the silicon oxynitride layer is in contact has an anti-reflection structure.

12. The solar cell of claim 1 , wherein the conductive region comprises a first conductive region having a first conductivity type and a second conductive region having a second conductive type opposite to the first conductive type,

wherein the electrode comprises a first electrode electrically connected to the first conductive region and a second electrode electrically connected to the second conductive region, and

wherein the first and second conductive regions and the first and second electrodes are positioned on or at a surface of the semiconductor substrate opposite to the light incident surface on which the silicon oxynitride layer is positioned.

13. The solar cell of claim 12 , wherein the silicon oxynitride layer is formed entirely on the light incident surface of the semiconductor substrate at a location where the electrode is not positioned.

14. The solar cell of claim 12 , wherein the first and second conductive regions are formed at a semiconductor layer separately positioned from the semiconductor substrate,

wherein a front surface field region formed of a doped region is positioned on or at the light incident surface of the semiconductor substrate, and

wherein the silicon oxynitride layer is in contact with the front surface field region.

15. The solar cell of claim 14 , further comprising a second passivation layer on the semiconductor layer, and

wherein the second passivation layer is formed entirely on the semiconductor layer except at contact holes for connecting the first and second electrodes to the first and second conductive regions.

16. The solar cell of claim 1 , wherein a thickness of the first phase region is different from that of the second phase region.

17. The solar cell of claim 1 , wherein the first phase region and the second phase region are each provided in plural, and a plurality of first phase regions and a plurality of second phase regions are alternately stacked in a thickness direction of the silicon oxynitride layer.