Methods of forming quantum dots of Group IV semiconductor materials

• US 6,794,265 B2
• Filed: 08/02/2002
• Issued: 09/21/2004
• Est. Priority Date: 08/02/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: UltraDots, Inc. (Omnipv Incorporated)
• Inventors: Gao, Bingshen, Keshavarz, Majid, Lee, Howard Wing Hoon
• Primary Examiner(s): Wille, Douglas A.
• Application Number:
  US10/212,004
• Publication Number:
  US 20040036130A1
• Time in Patent Office: 781 Days
• Field of Search: 438/409
• US Class Current: 438/409
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12097 Ridge, rib or the like
• CPC Class Codes: G02B 2006/12145 Switch
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 2006/12159 Interferometer
• CPC Class Codes: G02B 2006/12195 Tapering
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02F 1/01791 Quantum boxes or quantum dots
• CPC Class Codes: G02F 1/217 Multimode interference type
• CPC Class Codes: G02F 1/3515 All-optical modulation, gating, switching, e.g. control of a light beam by another light beam G02F1/353, G02F1/37, G02F1/39 take precedence
• CPC Class Codes: G02F 1/3517 using an interferometer
• CPC Class Codes: G02F 1/3521 using a directional coupler
• CPC Class Codes: G02F 1/3556 Semiconductor materials, e.g. quantum wells
• CPC Class Codes: G02F 1/365 in an optical waveguide structure G02F1/377, G02F1/395 take precedence
• CPC Class Codes: G02F 2/006 All-optical wavelength conversion
• CPC Class Codes: G02F 2202/32 Photonic crystals
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: H01L 29/127 Quantum box structures
• CPC Class Codes: H01L 29/16 : including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 29/1602 : Diamond

Abstract

The invention relates to a method of forming a quantum dot. A particle that includes a semiconductor material Y selected from the group consisting of Si and Ge is provided. Sound energy and light energy is applied to the particle to form a quantum dot. The quantum dot exhibits photoluminescence with a quantum efficiency that is greater than 10 percent. The quantum dot includes a core, and the core includes Y.

Claims

1. A method of forming a quantum dot, comprising:

providing a particle that includes a semiconductor material Y selected from the group consisting of Si and Ge; and

applying sound energy and light energy to said particle to form a quantum dot that exhibits photoluminescence with a quantum efficiency that is greater than 10 percent, said quantum dot including a core, said core including Y.

2. The method of claim 1, wherein said particle has a size between approximately 1 nm and 100 nm.

3. The method of claim 1, wherein providing said particle includes:

forming a porous layer on a substrate, said substrate including Y; and

processing said porous layer to form said particle.

4. The method of claim 1, further comprising:

dispersing said particle in a solvent, and

wherein applying said sound energy and said light energy to said particle includes applying said sound energy and said light energy to said particle in said solvent.

5. The method of claim 1, wherein applying said sound energy and said light energy to said particle includes:

applying said sound energy to said particle for a time sufficient to form said core with a diameter within a predetermined range.

6. The method of claim 1, wherein applying said sound energy and said light energy to said particle includes:

applying said sound energy to said particle for a time sufficient to form a shell surrounding said core.

7. The method of claim 6, wherein said shell includes an oxide YO_n with n being between approximately 0 and 2.

8. The method of claim 6, wherein said shell is substantially defect free.

9. The method of claim 1, wherein applying said sound energy and said light energy to said particle includes:

applying said light energy to said particle for a time sufficient to form said core with a diameter within a predetermined range.

10. A method of forming quantum dots, comprising:

providing particles having a first peak size, said particles including a semiconductor material Y selected from the group consisting of Si and Ge; and

applying light energy to said particles for a time sufficient to form quantum dots having a second peak size, said second peak size being smaller than said first peak size.

11. The method of claim 10, wherein said light energy is associated with a wavelength, and applying said light energy to said particles includes:

selecting said wavelength based on said second peak size.

12. The method of claim 10, wherein applying said light energy to said particles includes:

applying said light energy to said particles for a time sufficient to form said quantum dots having sizes exhibiting less than 20 percent root-mean-square deviation.

13. The method of claim 10, wherein each quantum dot includes a core and a shell surrounding said core, said core including Y, said shell including an oxide YO_n with n being between approximately 0 and 2, said method further comprising:

applying sound energy to said particles for a time sufficient to form said shell.

14. A method of forming a quantum dot, comprising:

reacting, in a reaction medium, a source of a semiconductor material Y selected from the group consisting of Si and Ge with a reducing agent to form a particle that includes a core, said core including Y, said reducing agent being selected from the group consisting of Group IIA metals, transition metals, and lanthanides; and

reacting said particle with a source of surface ligands to form a ligand layer surrounding said core to form a quantum dot, said ligand layer including at least one surface ligand.

15. The method of claim 14, wherein reacting said source of Y with said reducing agent includes:

mixing said source of Y and said reducing agent in said reaction medium.

16. The method of claim 14, wherein reacting said source of Y with said reducing agent includes:

mixing said source of Y and said reducing agent in said reaction medium at a pressure of approximately 1 atm.

17. The method of claim 14, wherein reacting said source of Y with said reducing agent includes:

maintaining said reaction medium at a temperature between approximately −

79°

C. and 300°

C.

18. The method of claim 14, wherein reacting said source of Y with said reducing agent includes:

maintaining said reaction medium at a temperature between approximately 60°

C. and 280°

C.

19. The method of claim 14, wherein said source of Y includes a compound having a structure given by the formula:

 

YX_a,

where a is an integer in the range of 2 to 4, and X is selected from the group consisting of —

F, —

Cl, —

Br, —

I, —

O—

CO—

R⁽¹⁾, —

NR⁽²⁾R⁽³⁾, —

OR⁽⁴⁾, and —

S—

R⁽⁵⁾, with R⁽¹⁾, R⁽²⁾, R⁽³⁾, R⁽⁴⁾, and R⁽⁵⁾ being independently selected from the group consisting of alkyls, alkenyls, alkynyls, and aryls.

20. The method of claim 14, wherein said reducing agent is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Sc, Ti, Zr, Mn, Fe, Co, Ni, Pd, Cu, Zn, Ce, and Sm.

21. The method of claim 14, further comprising:

providing said reducing agent in a powdered form; and

dispersing said reducing agent in said powdered form in said reaction medium.

22. The method of claim 14, wherein said reaction medium includes two different coordinating solvents.

23. The method of claim 14, wherein said reaction medium includes a solvent selected from the group consisting of oxygen-containing organic solvents, nitrogen-containing organic solvents, sulfur-containing organic solvents, and phosphorus-containing organic solvents.

24. The method of claim 14, wherein said source of surface ligands includes an organometallic compound.

25. The method of claim 24, wherein said organometallic compound has a structure given by the formula: