Fabrication, Structural And Electrical Characteristics Of Zinc Oxide (ZnO) Thin Films By Direct Current Sputtering
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Date
2009-01
Authors
Abdul Hamid, Haslinda
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Abstract
The wide band gap semiconductor of zinc oxide (ZnO) has emerged as a potential
material for the fabrication of a range of devices including opto-electronic devices such
as light - emitting diodes (LEDs), laser diodes (LDs) and detectors. There is still much
to be explored and understood about ZnO before such devices can be commercially
realized. Most notably, p-type doping of ZnO remains an issue, as does the origin of
the native n-type conductivity. Nevertheless, when p-type doping is obtained in ZnO it
could be used in various applications as mentioned above. The goals of this project
were to synthesize cod oped ZnO in the forms of thin films by using direct current (DC)
magnetron sputtering deposition technique and to study the structural and electrical
properties. A 99.99 % pure zinc target and 99.99 % pure rods of aluminium were
sputtered on silicon substrates using the direct current (DC) co-sputtering technique.
The films were then annealed in different ratios of nitrogen and oxygen at annealing
temperatures in the range of 200°C to 600 DC. The structural and electrical properties
of ZnO thin films grown were then characterized by atomic force microscopy (AFM),
,
scanning electron microscope (SEM), X-ray diffraction (XRD) and Hall Effect
measurements. From the results, all Zn films were fully converted to ZnO as confirmed
by XRD and film with p-type conduction was successfully produced by the AI-N
codoping method. This work also indicates that the film surface characteristics are
strongly influenced by the annealing temperatures and the ratios of nitrogen and
oxygen used. From the results obtained by AFM, the roughness of the surface
structure decreased with increasing of annealing temperature in the presence of large
amount of nitrogen. However, SEM revealed the distinct change on thin film surface
when the annealing temperature increased from 200°C to 600 °c in the presence of
oxygen and nitrogen. P-type ZnO thin films prepared at N2-to-02 ratio of 50% : 50%
and annealed at 200°C for 1 hour showed the lowest resistivity of 1.530 x 10-3 Q. cm
and the highest carrier concentration of +1.85 x 10
22
cm-
Description
Keywords
Zinc Oxide