Solar cell having an emitter region with wide bandgap semiconductor material
Solar cells having emitter regions composed of wide bandgap semiconductor material are described. In an example, a method includes forming, in a process tool having a controlled atmosphere, a thin dielectric layer on a surface of a semiconductor substrate of the solar cell. The semiconductor substrate has a bandgap. Without removing the semiconductor substrate from the controlled atmosphere of the process tool, a semiconductor layer is formed on the thin dielectric layer. The semiconductor layer has a bandgap at least approximately 0.2 electron Volts (eV) above the bandgap of the semiconductor substrate.
1. A solar cell, comprising:
a semiconductor substrate;
a thin dielectric layer disposed on the semiconductor substrate;
a first emitter region of a first conductivity type disposed on the thin dielectric layer, wherein the first emitter region comprises polycrystalline silicon;
a first oxide layer disposed on the semiconductor substrate; and
a second emitter region of a second conductivity type disposed on the first oxide layer, the second conductivity type opposite the first conductivity type, wherein the second emitter region comprises polycrystalline silicon, wherein a portion of the second emitter region is partially disposed over the first emitter region.
2. The solar cell of claim 1 , wherein the portion of the second emitter region is partially disposed over the thin dielectric layer.
3. The solar cell of claim 1 , wherein a portion of the first oxide layer is partially disposed over the first emitter region.
4. The solar cell of claim 1 , wherein a portion of the first oxide layer is partially disposed over the thin dielectric layer.
5. A solar cell, comprising:
a semiconductor substrate;
a thin dielectric layer disposed on the semiconductor substrate;
a first emitter region of a first conductivity type disposed on the thin dielectric layer, wherein the first emitter region comprises polycrystalline silicon;
a first oxide layer disposed on the semiconductor substrate; and
a second emitter region of a second conductivity type disposed on the first oxide layer, the second conductivity type opposite the first conductivity type, wherein the second emitter region comprises polycrystalline silicon and a portion of the second emitter region is partially disposed over the first emitter region.
6. The solar cell of claim 5 , wherein the portion of the second emitter region is partially disposed over the thin dielectric layer.
7. The solar cell of claim 5 , wherein a portion of the first oxide layer is partially disposed over the first emitter region.
8. The solar cell of claim 5 , wherein a portion of the first oxide layer is partially disposed over the thin dielectric layer.
9. The solar cell of claim 5 , wherein the first conductivity type is N-type, and the second conductivity type is P-type.
10. The solar cell of claim 5 , wherein the first conductivity type is P-type, and the second conductivity type is N-type.
11. The solar cell of claim 5 , wherein the second emitter region has a dopant concentration approximately in the range of 1×1017-1×1021 atoms/cm3.
12. The solar cell of claim 5 , wherein the first oxide layer comprises silicon oxide.
13. The solar cell of claim 5 , further comprising:
a second oxide layer disposed over a light receiving surface of the semiconductor substrate;
an amorphous silicon layer disposed on the second oxide layer; and
an anti-reflective coating (ARC) layer disposed on the amorphous silicon layer, the ARC layer comprising silicon nitride.
14. A solar cell, comprising:
a semiconductor substrate;
a thin dielectric layer disposed on the semiconductor substrate;
a first emitter region of a first conductivity type disposed on the thin dielectric layer, wherein the first emitter region comprises polycrystalline silicon;
a layer of doping material disposed on the first polycrystalline emitter region;
a first oxide layer disposed on the semiconductor substrate; and
a second emitter region of a second conductivity type disposed on the first oxide layer, the second conductivity type opposite the first conductivity type, wherein the second emitter region comprises polycrystalline silicon and a portion of the second emitter region is partially disposed over the first emitter region.
15. The solar cell of claim 14 , wherein the layer of doping material comprises a positive-type doping material.
16. The solar cell of claim 15 , wherein the positive-type doping material comprises boron.
17. The solar cell of claim 14 , wherein a portion of the second emitter region is partially disposed over the thin dielectric layer.
18. The solar cell of claim 14 , wherein the first conductivity type is N-type, and the second conductivity type is P-type.
19. The solar cell of claim 14 , wherein the first oxide layer comprises silicon oxide.