Process and apparatus for forming nanoparticles using radiofrequency plasmas
Methods and apparatus for producing nanoparticles, including single-crystal semiconductor nanoparticles, are provided. The methods include the step of generating a constricted radiofrequency plasma in the presence of a precursor gas containing precursor molecules to form nanoparticles. Single-crystal semiconductor nanoparticles, including photoluminescent silicon nanoparticles, having diameters of no more than 10 nm may be fabricated in accordance with the methods.
1. A method for producing semiconductor nanoparticles, comprising:
providing a continuous flow of a gas containing a semiconductor-containing precursor monomer through a plasma reactor having an inlet and an outlet;
applying a high frequency voltage between two electrodes arranged proximate the plasma chamber and thereby creating a capacitively coupled plasma in the plasma reactor;
dissociating the semiconductor-containing precursor in the plasma to provide precursor species that nucleate and grow into semiconductor nanoparticles wherein;
the precursor is primarily converted into nonagglomerated semiconductor nanoparticles in the high-frequency capacitively coupled plasma, and the nanoparticles are carried out of the reactor through the outlet in a continuous fashion.
2. The method of claim 1 , further comprising depositing the semiconductor nanoparticles onto a substrate.
3. The method of claim 2 , wherein the nanoparticles are deposited onto a substrate that moves in a continuous or step-wise fashion to produce a film of nanoparticles on the substrate.
4. The method of claim 1 , wherein the semiconductor nanoparticles comprise single-crystal semiconductor nanoparticles.
5. The method of claim 4 , wherein the single-crystal semiconductor nanoparticles have an average diameter of no more than about 50nm.
6. The method of claim 1 , wherein the semiconductor nanoparticles comprise Group IV semiconductor nanoparticles.
7. The method of claim 6 , wherein the Group IV semiconductor nanoparticles comprise silicon nanoparticles.
8. The method of claim 1 , wherein the semiconductor nanoparticles comprise Group II-IV semiconductor nanoparticles.
9. The method of claim 8 , wherein the Group II-VI semiconductor nanoparticles comprise CdSe nanoparticles.
10. The method of claim 1 , wherein the semiconductor nanoparticles comprise Group III-V semiconductor nanoparticles.
11. The method of claim 1 , wherein the semiconductor nanoparticles are photoluminescent nanoparticles.
12. The method of claim 1 , wherein the total pressure in the plasma reactor during the production of the semiconductor nanoparticles is less than about 5 Torr.
13. The method of claim 1 , wherein the total pressure in the plasma reactor during the production of the semiconductor nanoparticles is less than about 3 Torr.
14. The method of claim 1 , wherein the semiconductor nanoparticles have an average diameter of no more than about 10nm.
15. The method of claim 1 , wherein the semiconductor nanoparticles have an average diameter of no more than about 5nm.
16. The method of claim 1 , wherein at least one electrode comprises a ring electrode.
17. The method of claim 1 , wherein at least one electrode comprises a plate electrode.
18. The method of claim 1 , wherein dissociating the semiconductor precursor includes generating monodispersed nanoparticles.
19. The method of claim 1 , wherein the semiconductor nanoparticles comprise a mixture of elements from different groups of the periodic table.
20. The method of claim 1 , wherein at least one electrode surrounds a dielectric discharge tube.
21. The method of claim 1 , wherein the plasma reactor includes a plurality of inlets.