Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/02—Silicon
  • C01B33/021—Preparation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites

Definitions

• the invention concerns silicon nanoparticles.
• Applications of the invention include a wide range of electronic and opto-electronic applications.
• the invention provides a silicon nanoparticle formation method that can rapidly produce substantial quantities of silicon nanoparticles, which are readily recoverable for subsequent uses.
• a preferred method includes treating a silicon substrate with hexachloroplatinic acid and etching the silicon substrate with HFZH 2 O 2 to form silicon nanoparticles on the surface of the silicon.
• Preferred methods of the invention use a cathodization of silicon source material in hexachloroplatinic acid/HF/H 2 O 2 to form Si nanoparticles.
• Other embodiments use a currentless immersion of silicon material in hexachloroplatinic acid followed by etching.
• the silicon source material is a silicon substrate, e.g., a silicon wafer.
• the invention provides silicon nanoparticle formation processes that proceed to completion quickly, permitting formation of large quantities of nanoparticles.
• the rapidity of preferred embodiments makes the formation methods especially well-suited to commercial manufacturing processes. Preferred embodiments will now be discussed. Artisans will appreciate broader aspects of the invention from the description of the preferred embodiments.
• the invention provides a silicon nanoparticle formation method that can rapidly produce substantial quantities of silicon nanoparticles, which are readily recoverable for subsequent uses.
• a preferred method includes treating a silicon substrate with hexachloroplatinic acid and etching the silicon substrate with HFZH 2 O 2 to form silicon nanoparticles on the surface of the silicon.
• Preferred methods of the invention use a cathodization of silicon source material in hexachloroplatinic acid/HF/H 2 O 2 to form Si nanoparticles.
• Other embodiments use a currentless immersion of silicon material in hexachloroplatinic acid followed by etching.
• the silicon source material is a silicon substrate, e.g., a silicon wafer.
• a preferred embodiment of the invention is an electrochemical cathodization process in hexachloroplatinic acid/HF/H 2 O 2 of silicon wafers to form fluorescent silicon nanoparticles.
• This process runs to completion in a shorter time (can be less than one third of the time), consumes less electrical power, uses less raw silicon wafer material, and is more efficient than anodization in HFfH 2 O 2 used in U.S. Patent No. 6,585,947.
• the '947 patent produces highly uniform quantities of lnm particles, and the present process produces a distribution of nanoparticles.
• the wafer may be swept into the solution.
• a silicon wafer piece is immersed in the etchant solution as a cathode (cathodization) by connecting it to the negative terminal of the biasing source with its mirrored side facing an anode (anodization) (which is another similar silicon piece connected to the positive terminal of the biasing source) and the etchant solution is stirred gently.
• a typical current was set at about (1.5) m A.
• Magnetic stirring was used.
• a typical duration for maintaining current was about 5 min.
• the current source and magnetic stirrer were switched off at the same time. Silicon nanoparticles form on the surface of the wafer.
• the cathodized wafer sample was washed with de-ionized water, and flushed with inert gas.
• the etched film is seen by the naked eye as a stain on the immersed portion of the substrate. Under irradiation from commercial incoherent UV mercury lamp at 365 nm, red photoluminescence is observed with the naked eye. Sonicaton can be used to recover the nanoparticles from the surface of the wafer.
• the particles can be recovered in isopropyl, THF, DMSO, chloroform, or any other solvent.
• the range of size of the nanoparticles according to scanning electron microscopy is 6 to 1 nm with an average of ⁇ 3 nm, which exhibits red/yellow photoluminescence.
• the counter anodized wafer sample may also show some luminescence and the corresponding particles can also be harvested in a similar way.
• silicon wafer is cathodized in
• HF/hexachloroplatinic acid followed by cathodization in chloroplatinic acid, and then dipped in HF/H 2 O 2 for 15 seconds.
• the total period of treatment is 15 minutes or less.
• silicon wafer is immersed in HF/hexachloroplatinic acid for 15 minutes.
• the wafer is then transferred and dipped in an HF/H 2 O 2 mixture for 15 seconds.
• the process as such works in zero current.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Nanotechnology (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Composite Materials (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Silicon Compounds (AREA)

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• 2006
  • 2006-07-14 WO PCT/US2006/027243 patent/WO2007018959A2/en not_active Ceased
  • 2006-07-14 EP EP06787185A patent/EP1908112A2/de not_active Withdrawn

Non-Patent Citations (1)

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