Quantum dots, semiconductor nanocrystals and semiconductor particles used as fluorescent coding elements

• US 6,633,370 B2
• Filed: 03/07/2001
• Issued: 10/14/2003
• Est. Priority Date: 03/07/2000
• Status: Expired due to Fees

• Current Assignee: Solaris Nanosciences Incorporated
• Original Assignee: Spectra Science Corp. (Spectra Acquisition Corp.)
• Inventors: Lawandy, Nabil M.
• Primary Examiner(s): Frech, Karl D.
• Assistant Examiner(s): FRANKLIN, JAMARA ALZAIDA
• Application Number:
  US09/801,479
• Publication Number:
  US 20010033371A1
• Time in Patent Office: 951 Days
• Field of Search: 356/71, 235/454, 235/487, 235/494, 235/491
• US Class Current: 356/71
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 33/588 with semiconductor nanocrystal label, e.g. quantum dots

Abstract

A method is disclosed for obtaining information about an object, as is a system operating in accordance with the method. The method includes steps of (a) placing a plurality of regions onto the object, each region being capable of emitting a predetermined wavelength of light; (b) detecting the light; and (c) decoding information from the detected light. At least one of the regions contains semiconductor particles having a radius larger than a quantum dot radius for a corresponding semiconductor material, and a chemical composition selected to provide the predetermined wavelength of light. The semiconductor material contains at least one of a Group II-IV alloy, or a Group III-V alloy, or a compound comprised of an indirect bandgap material, such as Si or Ge. The concentrations of the alloy or compound constituent elements are preselected to provide the predetermined emission wavelength. The semiconductor material may further include a selected dopant.

Claims

1. A method for obtaining information about an object, comprising steps of:

placing a plurality of regions onto the object, each region emitting a predetermined wavelength of light;

detecting the light; and

decoding information from the detected light, wherein

at least one region is comprised of semiconductor particles having a radius larger than a quantum dot radius for a corresponding semiconductor material, and a chemical composition selected to provide the predetermined wavelength of light, where the semiconductor material is comprised of one of a Group II-VI alloy, or a Group III-V alloy, or a compound comprised of an indirect bandgap material, and wherein the concentrations of the alloy or compound constituent elements are preselected to provide the predetermined emission wavelength.

2. A method as in claim 1, wherein the semiconductor material is further comprised of a dopant.

3. A method as in claim 1, wherein the semiconductor material alloy has the form AB_xC₁₋

x, where A, B and C are each a different element.

4. A method as in claim 1, wherein the semiconductor material alloy has the form AB_xC₁₋

x, where A, B and C are each a different element, and where in at least two of said plurality of regions the value of x is different.

17. A method as in claim 1, wherein the indirect bandgap material is Si.

18. A method as in claim 1, wherein the indirect bandgap material is Ge.

5. A system for obtaining information about an object, comprising:

a plurality of regions associated with the object, each region emitting a predetermined wavelength of light;

a detector for detecting the light; and

a decoder for decoding information from the detected light, wherein

at least one region is comprised of semiconductor particles having a radius larger than a quantum dot radius for a corresponding semiconductor material, and a chemical composition selected to provide the predetermined wavelength of light, wherein the semiconductor material is comprised of one of a Group II-VI alloy, or a Group III-V alloy, or a compound comprised of an indirect bandgap material, and wherein the concentrations of the alloy or compound constituent elements are preselected to provide the predetermined emission wavelength.

6. A system as in claim 5, wherein the semiconductor material is further comprised of a dopant.

7. A system as in claim 5, wherein the semiconductor material alloy has the form AB_xC₁₋

x, where A, B and C are each a different element.

8. A system as in claim 5, wherein the semiconductor material alloy has the form AB_xC₁₋

x, where A, B and C are each a different element, and where in at least two of said plurality of regions the value of x is different.

9. A system for obtaining information about a substrate comprising:

a substrate having a plurality of discrete regions thereon, at least one of the discrete regions containing particles, each of the particles having a surface dimension greater than a quantum dot dimension for a corresponding semiconductor material, wherein the particles are preselected to emit an associated predetermined emission wavelength;

an excitation source, adapted to provide radiation that causes the particles of a particular region to emit the associated predetermined emission wavelength of the particular region;

a detection unit adapted to detect the associated predetermined emission wavelength from the particles of each region and the detection unit adapted to generate electrical signals as a function of the detected associated predetermined emission wavelength; and

a processing unit adapted to receive the electrical signals from the detection unit and process the electrical signals to establish a characteristic of the substrate.

10. A system as in claim 9, farther comprising:

a memory unit, coupled to the processing unit, the memory unit adapted to store data relating to selected characteristics of a plurality of substrates.

11. A system as in claim 9, wherein the particles include CdS_xSe₁₋

x.

12. A system as in claim 9, wherein the particles include ZnS_xSe₁₋

x.

13. A system as in claim 9, wherein each particle has a surface dimension that exceeds approximately 15 nanometers.

14. A system as in claim 9, wherein at least one region has particles comprised of an indirect bandgap material.

15. A system as in claim 14, wherein the indirect bandgap material is Si.

16. A system as in claim 14, wherein the indirect bandgap material is Ge.