NANOPARTICLE FABRICATION
Methods for fabricating at least one nanoparticle include providing one or more substrates and depositing a substance on the one or more substrates. At least one portion of the substance is heated or annealed so the at least one portion beads up on the one or more substrates due to cohesive forces of the substance being greater than adhesive forces between the substrate and the substance. In some methods, a pattern generation process is performed to define the at least one portion. A combination of a substance material for the substance and a substrate material for the one or more substrates may also be selected so that the at least one portion beads up into a predetermined shape. The substance may also be deposited on the one or more substrates with a sub-monolayer thickness or with gaps to further reduce a nanoparticle size.
1 . A method for fabricating at least one nanoparticle, the method comprising:
annealing a substance consisting of a first metal on a substrate consisting of a second metal for a time sufficient for the substance to form into at least one nanoparticle, wherein the first metal and the second metal are different metals.
2 . The method of claim 1 , wherein the first metal is gold and the second metal is chromium, platinum, palladium, or titanium.
3 . The method of claim 1 , wherein the first metal is silver and the second metal is chromium, platinum, palladium, or titanium.
4 . The method of claim 1 , wherein the first metal is copper and the second metal is chromium, platinum, palladium, or titanium.
5 . The method of claim 1 , wherein the first metal is aluminum and the second metal is chromium, platinum, palladium, titanium.
6 . The method of claim 1 , wherein the first metal is palladium and the second metal is chromium, platinum, or titanium.
7 . The method of claim 1 , wherein the annealing consists of exposing the substance to heat, pressure, ultrasound, mechanical vibration, magnetic fields, voltage, light, ultraviolet light, or electrical current.
8 . The method of claim 7 , wherein the annealing consists of heating the substance at a temperature below the melting point of the first metal.
9 . The method of claim 8 , wherein heating is at a temperature of about 300° C. to about 600° C., and the time sufficient is from about fifteen minutes to about two hours.
10 . The method of claim 1 , further comprising depositing the substance on the substrate prior to annealing the substance.
11 . The method of claim 10 , wherein the depositing consists of sputtering, chemical vapor deposition, electron beam lithography, photolithography, UV lithography, extreme UV lithography, X-ray lithography, nanoimprint lithography, ion beam milling, or CMOS lithography.
12 . The method of claim 10 , wherein the depositing consists of filling a hole or a spot patterned into a resist layer on the substrate.
13 . The method of claim 12 , further comprising removing the resist layer after the depositing and prior to the annealing.
14 . The method of claim 10 , wherein the depositing results in a disc shaped deposit of the first metal, and wherein the resulting nanoparticle thus formed by annealing is substantially spherical.
15 . The method of claim 10 , wherein the depositing results in an irregular shaped deposit of the first metal, and wherein the resulting nanoparticle thus formed by annealing is substantially spherical, with the substantially spherical nanoparticle located at a centroid or center of mass of the initial irregular shaped deposit.
16 . The method of claim 15 , wherein the irregular shaped deposit includes gaps, holes, bubbles, voids, or regions of sub-monolayer mean thickness.
17 . The method of claim 1 , wherein the first metal and the second metal are selected such that the nanoparticle thus formed has a dome shape instead of a lenticular shape or a spherical shape.
18 . The method of claim 1 , wherein the annealing consists of heating the substance and the substrate in an ambient medium including a vacuum, argon, nitrogen, air, an oil, a polymer, a metal, or a semiconductor material.