Solar cell and method for manufacturing the same
A method for manufacturing a solar cell may include forming an emitter region that forms a p-n junction with a semiconductor substrate of a first conductive type, forming a passivation layer on the semiconductor substrate, forming a dopant layer containing impurities of the first conductive type on the passivation layer, and locally forming a back surface field region at the semiconductor substrate by irradiating laser beams onto the semiconductor substrate to diffuse the impurities into the semiconductor substrate.
1. A solar cell, comprising:
a semiconductor substrate of a first conductive type;
an emitter region containing impurities of a second conductive type opposite to the first conductive type, and being positioned at the semiconductor substrate of a first conductive type;
a first electrode connected to the emitter region;
a passivation layer positioned on the semiconductor substrate, and having a contact hole;
a back surface field region positioned at the semiconductor substrate, and exposed by the contact hole;
a dopant layer containing impurities of the first conductive type, and being directly positioned on the passivation layer and contacting the back surface field region through the contact hole; and
a second electrode positioned on the dopant layer,
wherein the dopant layer contains the impurities of the first conductive type and is entirely positioned between the passivation layer and the second electrode,
wherein the dopant layer comprises a first surface facing the semiconductor substrate and a second surface opposite the first surface,
wherein the first surface of the dopant layer directly contacts an entire surface of the passivation layer that faces towards the dopant layer, and the entire second surface of the dopant layer directly contacts the second electrode,
wherein a composition of the dopant layer, which contains boron (B), is different from a composition of the second electrode, which contains aluminum (Al),
wherein the contact hole is filled with a mixture comprising a material of the dopant layer and a material of the second electrode,
wherein the mixture is a mixture (B+Al) of boron (B) and aluminum (Al), and
wherein the passivation layer is entirely and directly formed on a back surface of the semiconductor substrate, except for the back surface field region exposed by the contact hole.
2. The solar cell of claim 1 , wherein the dopant layer has a surface having a plurality of first depressed portions.
3. The solar cell of claim 2 , wherein the plurality of first depressed portions correspond to formation positions of a plurality of back surface field regions, respectively.
4. The solar cell of claim 2 , wherein the second electrode has a surface having a plurality of second depressed portions.
5. The solar cell of claim 4 , wherein the plurality of second depressed portions correspond to positions of a plurality of back surface field regions, respectively.
6. The solar cell of claim 1 , wherein the back surface field region has an impurity concentration of the first conductive type that is higher than an impurity concentration of the first conductive type of the semiconductor substrate.
7. The solar cell of claim 1 , wherein the dopant layer has an impurity concentration of the first conductive type that is higher than an impurity concentration of the first conductive type of the semiconductor substrate.
8. The solar cell of claim 1 , wherein shapes of the back surface field regions contacting the semiconductor substrate are one of a semicircle, a circular cone, a polygonal cone or a pyramid.
9. The solar cell of claim 1 , wherein the dopant layer comprises a plurality of dopant portions that are locally positioned on the passivation layer, and formation positions of the plurality of dopant portions correspond to formation positions of a plurality of back surface field regions.
10. The solar cell of claim 9 , wherein the second electrode comprises a plurality of second electrode portions that are locally positioned on the plurality of the dopant portions, respectively.
11. The solar cell of claim 9 , wherein the second electrode is positioned on the plurality of dopant portions and portions of the passivation layer on which the plurality of dopant portions are not positioned.
12. The solar cell of claim 1 , wherein the dopant layer directly contacts the back surface field region on one side and directly contacts the second electrode on the other side via the first surface and the second surface, respectively.
13. The solar cell of claim 1 , wherein the emitter region is entirely and directly formed on a front surface of the semiconductor substrate.