Zinc oxide nanotip and fabricating method thereof

Abstract

In the present invention, there are provided self-assembled ZnO nanotips grown on relatively low temperatures on various substrates by metalorganic chemical vapor deposition (MOCVD). The ZnO nanotips are made at relatively low temperatures, giving ZnO a unique advantage over other wide bandgap semiconductors such as GaN and SiC. The nanotips have controlled uniform size, distribution and orientation. These ZnO nanotips are of single crystal quality, show n-type conductivity and have good optical properties. Selective growth of ZnO nanotips also has been realized on patterned (100) silicon on r-sapphire (SOS), and amorphous SiO 2 on r-sapphire substrates. Self-assembled ZnO nanotips can also be selectively grown on patterned layers or islands made of a semiconductor, an insulator or a metal deposited on R-plane (01 1 2) Al 2 O 3 substrates as long as the ZnO grows in a columnar structure along the c-axis [0001] of ZnO on these materials. Such self-assembled ZnO nanotips and nanotip arrays are promising for applications in field emission displays and electron emission sources, photonic bandgap devices, near-field microscopy, UV optoelectronics, and bio-chemical sensors.

1 - 41 . (canceled)  
     
     
         42 . A method of fabricating selectively grown single crystal ZnO nanotip and a regular array of ZnO nanotips comprises: 
 providing a substrate having a surface plane orientation;    depositing a layer of material having a surface plane on said substrate to form a material substrate combination, wherein said combination serves as a base for growth of ZnO nanotips; and    depositing ZnO on said combination, wherein the ZnO grows on said layer of material to form one or more ZnO nanotips and a smooth ZnO film grows on the surface plane of the substrate.    
     
     
         43 . The method of  claim 42  wherein said ZnO columnar structure grows on said layer of material at temperatures in a range of 300° C.-500° C. by metalorganic chemical vapor deposition (MOCVD).  
     
     
         44 . The method of  claim 42  wherein said surface plane is a (012) R-plane and said substrate is single crystal sapphire (Al 2 O 3 ).  
     
     
         45 . The method of  claim 44  wherein said smooth ZnO epitaxial film is in [ ] direction with a c-axis of the ZnO film lying parallel to the R-plane Al 2 O 3 .  
     
     
         46 . The method of  claim 42  wherein said ZnO grows in a columnar structure with a c-axis of the ZnO perpendicular to the surface plane of said layer of material.  
     
     
         47 . The method of  claim 46  wherein said layer of material is a semiconductor, including Si, GaN films or a combination thereof.  
     
     
         48 . The method of  claim 46  wherein said layer of material is an insulator, including SiO 2 , Al 2 O 3  films or a combination thereof.  
     
     
         49 . The method of  claim 46  wherein said layer of material is a metal, including Al, Ag films or a combination thereof.  
     
     
         50 . The method of  claim 42  wherein said ZnO is single crystal columnar structure grown along the c-axis [0001] direction of ZnO.  
     
     
         51 . The selective growth method of  claim 42  wherein said material-substrate combination comprises silicon-on-sapphire (SOS) wafer.  
     
     
         52 . The method of  claim 42  further comprising: 
 selectively etching the silicon to form a R-plane sapphire pattern and a silicon pattern on said SOS substrate.    
     
     
         53 . The fabrication process of  claim 50  further comprising: 
 MOCVD growth of a ZnO epitaxial film on said R-plane sapphire pattern; and    MOCVD growth of ZnO nanotips on said silicon pattern.