Ohmic-rectifying conversion of Ni contacts on ZnO and the possible determination of ZnO thin film surface polarity.
The current-voltage characteristics of Ni contacts with the surfaces of ZnO thin films as well as single crystal (0001) ZnO substrate are investigated. The ZnO thin film shows a conversion from Ohmic to rectifying behavior when annealed at 800°C. Similar findings are also found on the Zn-polar surface of (0001) ZnO. The O-polar surface, however, only shows Ohmic behavior before and after annealing. The rectifying behavior observed on the Zn-polar and ZnO thin film surfaces is associated with the formation of nickel zinc oxide (Ni1-xZnxO, where x = 0.1, 0.2). The current-voltage characteristics suggest that a p-n junction is formed by Ni1-xZnxO (which is believed to be p-type) and ZnO (which is intrinsically n-type). The rectifying behavior for the ZnO thin film as a result of annealing suggests that its surface is Zn-terminated. Current-voltage measurements could possibly be used to determine the surface polarity of ZnO thin films.
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Kim Guan
KG
Saw
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Sau Siong
SS
Tneh
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Gaik Leng
GL
Tan
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Fong Kwong
FK
Yam
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Sha Shiong
SS
Ng
Nano-optoelectronics Research Laboratory, Universiti Sains Malaysia, Minden, Penang, Malaysia.
Zainuriah
Z
Hassan
D003460:Crystallization; D004553:Electric Conductivity; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction; D015034:Zinc Oxide / Q000737:chemistry*
D009532:Nickel; D015034:Zinc Oxide