Solar cell having doped semiconductor heterojunction contacts
View Patent ↗A silicon solar cell has doped amorphous silicon contacts formed on a tunnel silicon oxide layer on a surface of a silicon substrate. High temperature processing is unnecessary in fabricating the solar cell.
1. A method of fabricating a silicon solar cell with carrier contacts, the method comprising:
a) providing a silicon substrate having first and second opposing major surfaces, wherein the first major surface is a light incident side;
b) forming a dielectric layer on the second major surface, wherein the dielectric layer is a tunnel oxide layer;
c) forming a doped amorphous silicon layer on the dielectric layer; and
d) forming at least one of carrier acceptor contacts or carrier donor contacts that include at least a portion of the doped amorphous silicon layer, wherein the dielectric layer is continuous under each of the carrier contacts.
2. The method of claim 1 , wherein doped amorphous silicon has dopant in excess of 10 19 atoms per cc.
3. The method of claim 2 , wherein the dopant is a donor dopant.
4. The method of claim 3 , wherein the dopant comprises phosphorus.
5. The method of claim 2 , wherein the dopant is an acceptor dopant.
6. The method of claim 5 , wherein the dopant comprises boron.
7. The method of claim 1 wherein the dielectric layer has thickness on the order of 10-20 angstroms.
8. The method of claim 1 , wherein the dielectric layer comprises silicon oxide.
9. The method of claim 1 , wherein the dielectric layer prevents re-crystallization of the doped amorphous silicon layer by epitaxial growth from the silicon substrate.