Silicon-based visible and near-infrared optoelectric devices

Patent metadata

Field	Value
Publication number	US-10374109-B2
Application number	US-201715784756-A
Country	US
Kind code	B2
Filing date	Oct 16, 2017
Priority date	May 25, 2001
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

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.

First claim

What is claimed is:

1. A method for processing a silicon semiconductor substrate, comprising:
irradiating a surface of the silicon substrate with a plurality of circularly polarized short laser pulses so as to generate a plurality of surface structures,
wherein the short laser pulses have a pulse width in a range of about 50 femtoseconds to about 50 picoseconds, a central wavelength in a range of about 200 nm to about 1200 nm, and a fluence in a range of about 1 kJ/m 2 to about 12 kJ/m 2 , and
wherein the plurality of surface structures have a substantially circular base.

2. The method of claim 1 , further comprising exposing one or more locations of said semiconductor surface to a dopant during said step of irradiating the surface.

3. The method of claim 2 , wherein said dopant is an electron-donating dopant.

4. The method of claim 1 , wherein said short laser pulses are applied to said substrate surface at a repetition rate in a range of about 1 kHz to about 1 MHz.

5. The method of claim 1 , wherein the dopant comprises any of sulfur, nitrogen, chlorine, tellurium, and selenium.

6. The method of claim 1 , wherein the fluence is greater than 1 kJ/m 2 .

7. The method of claim 1 , wherein the fluence is greater than 3 kJ/m 2 .

8. The method of claim 1 , wherein the fluence is in a range of 3 kJ/m 2 to about 10 kJ/m 2 .

9. The method of claim 1 , wherein the fluence is in a range of 3 kJ/m 2 to about 8 kJ/m 2 .

10. The method of claim 1 , wherein the fluence is in a range of 1 kJ/m 2 to about 4 kJ/m 2 .

11. The method of claim 1 , wherein the fluence is about 4 kJ/m 2 .

12. The method of claim 1 , wherein the pulse width is in a range of about 50 to about 500 femtoseconds.

13. The method of claim 1 , wherein the pulse width is about 100 femtoseconds.

14. The method of claim 1 , wherein the central wavelength is about 400 nm.

15. The method of claim 1 , wherein the pulses are applied to the substrate surface at a repetition rate in a range to about 50 MHz.

16. The method of claim 2 , wherein the step of exposing comprises depositing the dopant over the silicon surface exposed to laser pulses.

17. The method of claim 2 , wherein the step of exposing comprises depositing the dopant over the irradiated surface of the silicon substrate.

Assignees

• Harvard College

Inventors

• Mazur Eric
• Carey James Edward

Classifications

• H10P14/3816

  Pulsed laser beam · CPC title

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H10P34/42

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• Y02E10/52

  PV systems with concentrators · CPC title

• Y10S438/94

  Laser ablative material removal · CPC title