NANOSTRUCTURED DEVICES
A photovoltaic device is provided. It comprises at least two electrical contacts, p type dopants and n type dopants. It also comprises a bulk region and nanowires in an aligned array which contact the bulk region. All nanowires in the array have one predominant type of dopant, n or p, and at least a portion of the bulk region also comprises that predominant type of dopant. The portion of the bulk region comprising the predominant type of dopant typically contacts the nanowire array. The photovoltaic devices' p-n junction would then be found in the bulk region. The photovoltaic devices would commonly comprise silicon.
1 . A photovoltaic device comprising:
a multi-crystalline silicon bulk comprising:
a lower p-doped volume; and
an upper n-doped volume adjacent to and in direct physical contact with the p-doped volume;
an n-doped nanostructure on a surface of the n-doped volume; and
a p-n junction within the multi-crystalline silicon substrate and between 30 nm and 300 nm below a base of the nanostructure.
2 . The photovoltaic device of claim 1 further comprising a metal contact on the surface of the n-doped volume.
3 . The photovoltaic device of claim 2 wherein the metal contact comprises silver.
4 . The photovoltaic device of claim 3 further comprising an oxide between a portion of the silver metal contact and the surface of the n-doped volume.
5 . The photovoltaic device of claim 2 further comprising an oxide between a portion of the metal contact and the surface of the n-doped volume.
6 . The photovoltaic device of claim 2 wherein the metal contact is a screen printed metal contact.
7 . The photovoltaic device of claim 6 wherein the screen-printed metal contact comprises silver.
8 . The photovoltaic device of claim 4 wherein the metal contact is a screen printed metal contact.
9 . The photovoltaic device of claim 1 wherein the p-n junction is between 150 nm and 250 nm below the base of the nanostructure.
10 . The photovoltaic device of claim 1 wherein the p-n junction is substantially planar.
11 . The photovoltaic device of claim 10 wherein the p-n junction is substantially parallel to a bottom surface of the p-doped volume.
12 . The photovoltaic device of claim 1 wherein the p-n junction is substantially continuous.
13 . The photovoltaic device of claim 1 wherein the upper n-doped volume has a maximum doping concentration less than about 10 18 cm −3 .
14 . A photovoltaic device comprising:
a multi-crystalline silicon bulk comprising:
a lower p-doped volume; and
an upper n-doped volume adjacent to and in direct physical contact with the p-doped volume;
more than one n-doped nanostructures formed on a surface of the n-doped volume;
a p-n junction between 30 nm and 300 nm below the surface of the n-doped volume;
an oxide on the surface of the n-doped volume; and
a metal contact, wherein the metal contact comprises silver, on the surface of the n-doped volume and on a portion of the oxide.
15 . The photovoltaic device of claim 14 wherein the upper n-doped volume has a maximum doping concentration less than about 10 18 cm −3 .
16 . The photovoltaic device of claim 14 wherein the p-n junction is between 150 nm and 250 nm below the base of the nanostructure.
17 . The photovoltaic device of claim 14 wherein the metal contact is a screen-printed metal contact.
18 . A photovoltaic device comprising:
a mono crystalline silicon bulk comprising:
a lower p-doped volume; and
an upper n-doped volume adjacent to and in direct physical contact with the p-doped volume;
an n-doped nanostructure formed on a surface of the n-doped volume; and
a p-n junction within the mono-crystalline silicon substrate and between 30 nm and 3 microns below a base of the nanostructure.
19 . The photovoltaic device of claim 18 wherein the p-n junction within the mono-crystalline silicon substrate is between 30 nm and 300 nm below a base of the nanostructure.
20 . The photovoltaic device of claim 18 further comprising a metal contact on the surface of the n-doped volume, wherein the metal contact is screen printed.