Gas sensor having zinc oxide nano-structures and method of fabricating the same
View Patent ↗A gas sensor includes zinc oxide nano-structures formed on a substrate, a plurality of metal islands coated on a surface of each zinc oxide nano-structure and separated from one another, a first electrode electrically connected to one end of each zinc oxide nano-structure through the substrate, a second electrode electrically connected to the other end of each zinc oxide nano-structure, and a current variation-measuring unit electrically connected to each of the first electrode and the second electrode so as to measure a variation in the amount of current flowing between the first electrode and the second electrode. In order to form the plurality of metal islands on the zinc oxide nano-structures, a solution of metal components of a metal material is coated on the surface of each zinc oxide nano-structure.
1. A method of fabricating a gas sensor, the method comprising:
forming a plurality of metal islands separated from one another on a surface of each of a plurality of zinc oxide nano-structures by coating a solution in which a metal material is dissolved on the surface of each zinc oxide nano-structure; and
forming a first electrode to be electrically connected to ends of the zinc oxide nano-structures and a second electrode to be electrically connected to the other ends of the zinc oxide nano-structures.
2. The method of claim 1 , further comprising, before forming the first electrode and the second electrode, evaporating water from the surfaces of the zinc oxide nano-structures in which the metal islands are formed.
3. The method of claim 1 , wherein the metal material is a metal powder.
4. The method of claim 1 , wherein the solution is kept in a temperature range of 30-100° C. while the plurality of metal islands are formed.
5. The method of claim 1 , wherein a concentration of metal in the solution is 1-70 wt % based on a total weight of the solution.
6. The method of claim 1 , wherein the zinc oxide nano-structures are dipped in the solution for a period of time in the range of one second to one minute so as to form the plurality of metal islands.
7. The method of claim 1 , further comprising, before forming the plurality of metal islands, forming the zinc oxide nano-structures on the substrate, wherein the forming of the plurality of metal islands comprises dipping the substrate on which the zinc oxide nano-structures are formed in the solution.
8. The method of claim 1 , wherein the solution comprises the metal material dissolved in aqua regia.
9. The method of claim 8 , wherein the solution further comprises at least one selected from distilled water and a base solution.
10. the method of claim 9 , wherein the base solution comprises ammonium hydroxide.
11. The method of claim 1 , wherein the metal material is a metal organic compound.
12. The method of claim 11 , wherein the metal material is formed of one metal organic compound selected from the group consisting of H 2 PtCl 6 , MeCpPtMe 3 , Pt(acac) 2 , Pd 2 (allyl) 2 Cl 2 , and Pd(C 3 H 5 )(C 5 H 5 ), where Me=methyl, Cp=cyclopentadienyl, and acac=acetyl-acetone.
13. A gas sensor fabricated by the method of claim 1 .
14. The gas sensor of claim 13 , wherein the metal islands have a grain size ranging from about 2 nm to about 50 nm.