Back-contact photovoltaic cell comprising a thin lamina having a superstrate receiver element
View Patent ↗A method to fabricate a photovoltaic device includes forming first and second contact regions at the first surface of a semiconductor donor body. A cleave plane may be formed by implanting ions into the donor body, and a lamina that includes the contact regions is cleaved from the donor body at the cleave plane. The first surface of the lamina may be contacted with a temporary support and fabricated into a photovoltaic device, wherein the lamina comprises the base of the photovoltaic device.
1. A method to fabricate a photovoltaic device, the method comprising the steps of:
a) providing a semiconductor donor body doped with a first conductivity type, the semiconductor donor body comprising a first dopant concentration and a first surface;
b) forming a first contact region at the first surface and within the semiconductor donor body, wherein the first contact region has the first conductivity type at a second dopant concentration, the second dopant concentration being higher than the first dopant concentration;
c) forming a second contact region at the first surface and within the semiconductor donor body, wherein the second contact region is doped with a second conductivity type;
d) implanting ions into a depth from the first surface of the semiconductor donor body to define a cleave plane, after the steps of forming the first contact region and forming the second contact region;
e) cleaving a lamina from the donor body at the cleave plane, wherein the step of cleaving the lamina forms a second surface on the lamina opposite the first surface, and wherein the lamina comprises the first and second contact regions;
f) contacting the first surface of the lamina to a temporary support; and
g) fabricating a photovoltaic device, wherein the lamina comprises a base of the photovoltaic device.
2. The method of claim 1 wherein the cleaving step occurs after the steps of forming the first contact region and forming the second contact region.
3. The method of claim 1 wherein the lamina has a thickness between the first and second surfaces, and wherein the thickness is between about 0.5 and about 20 microns.
4. The method of claim 1 further comprising the step of contacting a receiver element to the second surface of the lamina.
5. The method of claim 4 wherein contacting the receiver element to the second surface of the lamina occurs before fabricating the photovoltaic device.
6. The method of claim 4 wherein the receiver element is optically transparent.
7. The method of claim 4 wherein the receiver element is glass.
8. The method of claim 1 wherein the semiconductor donor body is a monocrystalline silicon wafer.
9. The method of claim 1 wherein the depth of the cleave plane from the first surface defines the thickness of the crystalline portion of the photovoltaic cell.
10. The method of claim 1 wherein, after the cleaving step, processing temperature does not exceed about 450° C.