Low resistivity copper doped cobalt oxide thin films by reactive ion beam sputter deposition
JUN-RON LI1*, LIANG-CHIUN CHAO2, BO-DA KE1
1Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
2Graduate Institute of Electro-optical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
* presenting author:JUN-RON LI, email:th791216@yahoo.com.tw
Copper doped cobalt oxide thin films were deposited at 300, 423 and 573K on glass substrates by reactive ion beam sputter deposition. A metallic cobalt target (99.99%) was positioned at 30 mm downstream of an ion source while substrates were positioned at 65 mm upstream of the target. Copper pieces (99.99%) were positioned on the cobalt target and the concentration of copper in cobalt oxide was controlled by varying the amount of copper pieces on the cobalt target. Both argon and oxygen were passed simultaneously through the ion source to act as sputtering and reacting species, respectively. Experimental results show that as oxygen partial flow rate increases from 20% to 100%, the resistivity of un-doped cobalt oxide thin film drops from 5 Ω·m to 1 Ω·cm. However, the resistivity of copper doped cobalt oxide drops significantly to 1.0×10-3 Ω·cm as oxygen partial flow rate reaches 100%. XPS analysis suggests that the change in resistivity is due to the presence of defects that results in increased carrier concentration. Results on transmittance and Hall measurement will also be presented.


Keywords: Cobalt oxide, Thin films deposited, Reactive ion beam sputter deposition, Copper