Method to grow carbon thin films consisting entirely of diamond grains 3-5 nm in size and high-energy grain boundaries

Abstract

An ultrananocrystalline diamond (UNCD) having an average grain size between 3 and 5 nanometers (nm) with not more than about 8% by volume diamond having an average grain size larger than 10 nm. A method of manufacturing UNCD film is also disclosed in which a vapor of acetylene and hydrogen in an inert gas other than He wherein the volume ratio of acetylene to hydrogen is greater than 0.35 and less than 0.85, with the balance being an inert gas, is subjected to a suitable amount of energy to fragment at least some of the acetylene to form a UNCD film having an average grain size of 3 to 5 nm with not more than about 8% by volume diamond having an average grain size larger than 10 nm.

1 . An ultrananocrystalline diamond (UNCD) having an average grain size between 3 and 5 nanometers (nm) with not more than about 8% by volume diamond having an average grain size larger than 10 nm.  
     
     
         2 . The UNCD of  claim 1 , wherein diamond having an average grain size larger than 10 nm is present in an amount less than 6% by volume.  
     
     
         3 . The UNCD of  claim 1 , wherein diamond having an average grain size larger than 10 nm is present in an amount in the range of from about 3% by volume to not more than about 8% by volume.  
     
     
         4 . The UNCD of  claim 1 , wherein said UNCD has grain boundaries of about 0.4 nm.  
     
     
         5 . The UNCD of  claim 1 , wherein said UNCD is essentially sp 3 -bonded diamond.  
     
     
         6 . The UNCD of  claim 1 , wherein substantially all sp 2 -bonded carbon present is at the UNCD grain boundaries.  
     
     
         7 . The UNCD of  claim 1 , wherein the UNCD grain boundaries are high energy.  
     
     
         8 . The UNCD of  claim 1 , wherein the UNCD grain boundaries are high-angle twist.  
     
     
         9 . An UNCD having average grain size between 3 and 5 nm with diamond having average grain size larger than 10 nm present in the range of from about 3% by volume to not more than 8% by volume and wherein the UNCD is essentially sp 3  bonded diamond and wherein substantially all sp 2  bonded carbon present is at the UNCD grain boundaries.  
     
     
         10 . A method of manufacturing UNCD film, comprising forming a vapor of acetylene and hydrogen that is thermally stable at 1000° K in an inert gas other than He wherein the volume ratio of acetylene to hydrogen is greater than 0.35 and less than 0.85, with the balance being an inert gas, subjecting the vapor to a suitable amount of energy to fragment at least some of the acetylene, and contacting the fragment containing vapor and a substrate, and forming an UNCD film having an average grain size of 3 to 5 nm with not more than about 8% by volume diamond having an average grain size larger than 10 nm on the substrate.  
     
     
         11 . The method of  claim 10 , wherein the fragment containing vapor has substantially no methyl radicals and the ratio of C 2 H 2  to H 2  is greater than 0.35 and less than about 0.7.  
     
     
         12 . The method of  claim 10 , wherein the substrate temperature is maintained at about 600° C. or lower during film formation.  
     
     
         13 . The method of  claim 10 , wherein the energy is microwave energy.  
     
     
         14 . The method of  claim 10 , wherein the inert gas is argon.  
     
     
         15 . The method of  claim 10 , wherein the UNCD film has diamond with average grain sizes larger than 10 nm present in a volume percent in the range of from about 3% to not more than about 8%.  
     
     
         16 . The method of  claim 10 , wherein the UNCD is deposited at a rate of not less than 0.2 micrometers per hour while the substrate is maintained at a temperature of less than about 600° C.  
     
     
         17 . The method of  claim 10 , wherein the UNCD is deposited at a rate of not less than 0.4 micrometers per hour while the substrate is maintained at a temperature of less than about 400° C.  
     
     
         18 . A method of manufacturing UNCD film, comprising forming a vapor of C 2 H 2  and H 2  in an inert gas of Ar and/or Kr wherein the C 2 H 2  to H 2  volume ratio is greater than 0.35 and less than 0.85, with the balance being the inert gas, fragmenting at least some of the C 2 H 2  by providing microwave energy to the vapor, and contacting the vapor containing acetylene fragments and a substrate maintained at a temperature less than about 600° C. to form an UNCD film having an average grain size of 3 to 5 nm with not more than about 8% by volume diamond having an average grain size larger than 10 nm on the substrate.  
     
     
         19 . The method of  claim 18 , wherein the inert gas is argon.  
     
     
         20 . The method of  claim 19 , wherein the UNCD film has diamond with average grain sizes larger than 10 nm present in a volume percent in the range of from about 3% to not more than about 8% and the C 2 H 2  to H 2  ratio is greater than 0.35 and less than about 0.7.  
     
     
         21 . The method of  claim 20 , wherein the UNCD is deposited at a rate of not less than 0.2 micrometers per hour while the substrate is maintained at a temperature of less than about 600° C.  
     
     
         22 . The method of  claim 18 , wherein the UNCD is deposited at a rate of not less than 0.4 micrometers per hour while the substrate is maintained at a temperature of less than about 400° C.  
     
     
         23 . A UNCD film made according to the method of  claim 18 .  
     
     
         24 . A UNCD film made according to the method of  claim 21 .  
     
     
         25 . A method of manufacturing UNCD film, comprising forming a vapor of a carbon containing compound that does not readily form methyl radicals upon fragmentation and hydrogen that is thermally stable at 1000° K in an inert gas other than He wherein the concentration of hydrogen is less than 1.5% by volume, with the balance being an inert gas, subjecting the vapor to a suitable amount of energy to fragment at least some of the carbon containing vapor, and contacting the fragment containing vapor and a substrate, and forming an UNCD film having an average grain size of 3 to 5 nm with not more than 8% by volume diamond having an average grain size larger than 10 nm on the substrate.  
     
     
         26 . The method of  claim 25 , wherein the carbon containing compound is one or more of a fullerene, acetylene and anthracene.  
     
     
         27 . An article of manufacture made by the method of  claim 26.