Methods for the production of nanoscale heterostructures
The present invention is directed to a novel synthetic method for producing nanoscale heterostructures, and particularly nanoscale heterostructure particles, rods and sheets, that comprise a metal core and a monocrystalline semiconductor shell with substantial lattice mismatches between them. More specifically, the invention concerns the use of controlled soft acid-base coordination reactions between molecular complexes and colloidal nanostructures to drive the nanoscale monocrystalline growth of the semiconductor shell with a lattice structure incommensurate with that of the core. The invention also relates to more complex hybrid core-shell structures that exhibit azimuthal and radial nano-tailoring of structures. The invention is additionally directed to the use of such compositions in semiconductor devices.
1. A method for producing a nanoscale heterostructure composed of a central metal core and an externally enveloping crystalline semiconductor shell, with more than 2% lattice mismatches between said core and said shell, wherein said method comprises the steps:
(A) forming an enveloping metal (Me) overlayer over said metal core, said metal core having a diameter of from about 4 nm to about 6 nm; wherein Me is a metal possessing soft Lewis acidity;
(B) incubating said composition (A) in the presence of:
(1) an anion (X) under conditions sufficient to convert said enveloping metal (Me) overlayer into an enveloping Me 2 X shell of amorphous structure; and
(2) a soft Lewis base (sLB); and
(3) a transport metal ion (M n+ )
under conditions sufficient to cause the expulsion of said Me metal from said Me 2 X shell and the formation of a crystalline Mn n+ -X shell enveloping said metal core;
thereby forming said nanoscale heterostructure.
2. The method of claim 1 , wherein said heterostructure is a particle, wire or sheet.
3. The method of claim 1 , wherein said metal Me is Ag.
4. The method of claim 1 , wherein said anion X is S 2− , Se 2− or Te 2− .
5. The method of claim 1 , wherein said soft Lewis base (sLB) is TBP (tri-n-butylphosphate).
6. The method of claim 1 , wherein said transport metal ion (M n+ ) is Cd, Zn or Pb.
7. The method of claim 1 , wherein said semiconductor shell comprises one or two semiconductor material(s).
8. The method of claim 1 , wherein said semiconductor shell comprises a single semiconductor material.
9. The method of claim 1 , wherein said semiconductor shell has a thickness of from about 2 nm to about 4 nm.
10. The method of claim 1 , wherein said nanoscale heterostructure possesses more than 20% lattice mismatches between said core and said shell.
11. The method of claim 1 , wherein said nanoscale heterostructure possesses more than 40% lattice mismatches between said core and said shell.
12. A semiconductor device that comprises a nanoscale heterostructure produced by the method of claim 1 .
13. A nanoscale heterostructure produced by the method of claim 1 .
14. The nanoscale heterostructure of claim 13 , wherein:
(a) Me is Ag;
(b) X is S 2− , Se 2− or Te 2− ;
(c) sLB is TBP (tri-n-butylphosphate); and
(d) M n+ is Cd, Zn or Pb.
15. The method of claim 1 , wherein said central core comprises one or two metals.
16. The method of claim 15 , wherein said metal of said central core comprises Au, Fe, Pd or Pt.
17. The method of claim 16 , wherein said central core comprises a single metal.
18. The method of claim 17 , wherein said single metal of said central core is Au, Pd or Pt.
19. The method of claim 18 , wherein said single metal is Au.