Three-terminal interdigitated back contact photoelectric device
Three-terminal (3T) photoelectrodes with cathodic protection capability are described. The 3T photoelectrodes utilize the third (i.e., the “extra”) electrode to bypass the diode in a semiconductor circuit and pass current with significant reductions in corrosions or reverse bias. The 3T photoelectrodes may be operated in diode mode when exposed to illumination and switched to an ohmic mode when light is significantly reduced (i.e., in the dark) to enable cathodic protection. The 3T photocathodes may maintain photoelectrochemical (PEC) activity in methyl viologen electrolyte under light/dark cycling. The 3T photoelectrodes may enable PEC in conditions where variable illumination is a regular occurrence.
1 . A photoelectric device comprising:
a wafer having a first side and a second side;
a first n-type contact located on the first side;
a second n-type contact located on the second side; and
a p-type contact located on the second side; wherein:
the p-type contact and the second n-type contact are arranged in parallel,
the first n-type contact and the p-type contact are connected via a diode,
the diode is configured to allow a current to flow when the photoelectric device is exposed to a light source, and
the diode is configured to not allow a current to flow when the photoelectric device is not exposed to a light source.
2 . The photoelectric device of claim 1 , wherein:
the wafer comprises a crystalline Czochralski-grown n-type silicon (Si) wafer.
3 . The photoelectric device of claim 1 , wherein:
the first n-type contact comprises a diffused n+-Si front surface field.
4 . The photoelectric device of claim 1 , wherein:
the second n-type contact comprises a degeneratively doped Si region.
5 . The photoelectric device of claim 1 , wherein:
the p-type contact comprises a degeneratively doped Si region.
6 . The photoelectric device of claim 1 , wherein:
the second side comprises:
a Si oxide,
a Si nitride, and
a conductive metal.
7 . The photoelectric device of claim 6 , wherein:
the conductive metal comprises at least one of silver, copper, or gold.
8 . A method of operating a photoelectric device, the method comprising:
operating the photoelectric device in a diode mode; and
operating the photoelectric device in an ohmic mode; wherein:
in the ohmic mode a current does not cross a diode, and
the photoelectric device comprises:
a wafer having a first side and a second side;
a first n-type contact located on the first side;
a second n-type contact located on the second side; and
a p-type contact located on the second side;
the p-type contact and the second n-type contact are arranged in parallel,
the first n-type contact and the p-type contact are connected via a diode,
the diode is configured to allow a current to flow when the photoelectric device is exposed to a light source, and
the diode is configured to not allow a current to flow when the photoelectric device is not exposed to a light source.
9 . The method of claim 8 , wherein:
the diode mode comprises connecting the first n-type contact and the p-type contact.
10 . The method of claim 8 , wherein:
the ohmic mode comprises connecting the first n-type contact with the second n-type contact.
11 . The method of claim 8 , wherein:
the diode comprises a semiconductor layer.
12 . The method of claim 8 , wherein:
the wafer comprises a crystalline Czochralski-grown n-type silicon (Si) wafer.
13 . The method of claim 8 , wherein:
the first n-type contact comprises a diffused n+-Si front surface field.
14 . The method of claim 8 , wherein:
the second n-type contact comprises a degeneratively doped Si region.
15 . The method of claim 8 , wherein:
the p-type contact comprises a degeneratively doped Si region.
16 . The method of claim 8 , wherein:
the second side comprises:
a Si oxide,
a Si nitride, and
a conductive metal.
17 . The method of claim 16 , wherein:
the conductive metal comprises at least one of silver, copper, or gold.