Heavily doped metal oxides and methods for making the same
View Patent ↗A method of making a doped metal oxide includes heating a first doped metal oxide by rapid thermal annealing, to form a second doped metal oxide. The crystal structure of the second doped metal oxide is different from the crystal structure of the first doped metal oxide. The method may provide a doped titanium oxide, where the atomic ratio of dopant nonmetal to titanium is from 2% to 20%, and at least 10% of the doped titanium oxide is in the rutile phase. The method also can provide a doped tin oxide, where the atomic ratio of dopant nonmetal to tin is from 2% to 20%, and at least 50% of 900 the doped tin oxide is in the rutile phase.
1. A method of making a doped metal oxide, comprising:
heat treating a first doped metal oxide comprising a dopant nonmetal rapid thermal annealing to form a second doped metal oxide, the heat treating comprising:
heating the first doped metal oxide at a heating rate of from 5°/s to 50°/s to a temperature of from 500° C. to 1,500° C.; and
maintaining the temperature from 1 minute to 10 minutes; and
after the heat treating, cooling to a temperature of less than 100° C. within 10 minutes;
where the crystal structure of the second doped metal oxide is different from the crystal structure of the first doped metal oxide.
2. The method of claim 1 , where the dopant nonmetal is selected from the group consisting of boron, carbon, nitrogen, fluorine and chlorine.
3. The method of claim 1 , where the atomic ratio of metal to oxygen to dopant nonmetal in the first doped metal oxide is 1:0.5-1.99:0.01-1.5.
4. The method of claim 1 , where the atomic ratio of metal to oxygen to dopant nonmetal in the first doped metal oxide is 1:1.8-1.9:0.1-0.2.
5. The method of claim 1 , where the atomic ratio of metal to dopant nonmetal in the second doped metal oxide is from 1:0.5-1.99:0.01-1.5.
6. The method of claim 1 , where the atomic ratio of metal to oxygen to dopant nonmetal 1:1.88-1.98:0.02-0.12.
7. The method of claim 1 , where the amount of dopant nonmetal in the second doped metal oxide is at least 10% of the amount of dopant nonmetal in the first doped metal oxide.
8. The method of claim 1 , where the amount of dopant nonmetal in the second doped metal oxide is at least 30% of the amount of dopant nonmetal in the first doped metal oxide.
9. The method of claim 1 , where the amount of dopant nonmetal in the second doped metal oxide is at least 85% of the amount of dopant nonmetal in the first doped metal oxide.
10. The method of claim 1 , further comprising forming the first doped metal oxide by reactive sputtering.
11. The method of claim 10 , where the reactive sputtering comprises sputtering a target comprising the metal or an oxide of the metal in an atmosphere comprising a dopant nonmetal source.
12. The method of claim 11 , where the atmosphere further comprises oxygen.