Silicon-based visible and near-infrared optoelectric devices
In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.
1. A semiconductor device, comprising
a radiation-absorbing semiconductor substrate having a surface layer including a dopant,
said doped surface layer exhibiting a sheet charge density in a range of about 10 12 cm −2 to about 10 14 cm −2 ,
wherein said semiconductor substrate exhibits a responsivity greater than about 1 ampere/watts (A/W) in response to exposure to radiation for at least one wavelength in a range of about 600 nm to about 1050 nm.
2. The device of claim 1 , wherein said doped surface layer has a thickness in a range of about 10 nm to about 1 micron.
3. The device of claim 1 , wherein said semiconductor substrate exhibits a responsivity greater than about 0.1 amperes/watts (A/W) in response to exposure to radiation having at least one wavelength in a range of about 1050 nm to about 3500 nm.
4. The device of claim 1 , wherein said dopant comprises an electron-donating dopant.
5. The device of claim 1 , wherein said dopant is selected from the group consisting of sulfur, nitrogen, chlorine, tellurium and selenium.
6. The device of claim 1 , wherein said doped surface layer exhibits a dopant concentration in a range of about 0.1 atom percent to about 5 atom percent.
7. The device of claim 1 , wherein said device comprises a photoconductive device.
8. The device of claim 1 , wherein said device comprises a photovoltaic device.
9. The device of claim 1 , wherein said substrate exhibits said responsivity upon application of a reverse bias voltage to said doped surface layer in a range of about 0.5 V to about 15 V.
10. The device of claim 1 , wherein said substrate comprises a silicon substrate.
11. The device of claim 1 , wherein said substrate comprises a p-doped crystalline silicon substrate.
12. The device of claim 1 , wherein said substrate comprises an n-doped crystalline silicon substrate.
13. The device of claim 1 , wherein said substrate has a bulk resistivity greater than about 1 ohm-m.
14. A semiconductor device, comprising
a radiation-absorbing semiconductor silicon substrate having a surface layer including a dopant,
said doped surface layer exhibiting a sheet charge density in a range of about 10 12 cm −2 to about 10 14 cm −2 ,
wherein said semiconductor substrate exhibits a responsivity greater than about 0.1 amperes/watts (A/W) in response to exposure to radiation having at least one wavelength in a range of about 1100 nm to about 3500 nm.
15. The device of claim 14 , wherein said doped surface layer has a thickness in a range of about 10 nm to about 1 micron.
16. The device of claim 14 , wherein said dopant comprises an electron-donating dopant.
17. The device of claim 14 , wherein said dopant is selected from the group consisting of sulfur, nitrogen, chlorine, tellurium and selenium.
18. The device of claim 14 , wherein said doped surface layer exhibits a dopant concentration in a range of about 0.1 atom percent to about 5 atom percent.
19. The device of claim 14 , wherein said device comprises a photoconductive device.
20. The device of claim 14 , wherein said device comprises a photovoltaic device.
21. The device of claim 14 , wherein said substrate exhibits said responsivity at a zero applied bias.