FABRICATION, STRUCTURAL AND ELECTRICAL CHRACTERISTICS OF P – TPYE ZNO THIN FILMS

Presenter	:	HASLINDA ABDUL HAMID
E-mail	:	-
Date	:	4 / 4 / 2008
Time	:	3.00 PM
Venue	:	BILIK PERSIDANGAN SEMENTARA (CEMACS),ARAS 1, PUSAT PENGAJIAN SAINS FIZIK
Sypnosis	:	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 codoped 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 co – sputtering technique of 99.99 % pure zinc target and 99.99 % pure rods of aluminium were DC sputtered on silicon substrates. The films were then annealed in different ratios of nitrogen and oxygen at annealing temperatures in the range of 200 °C to 600 °C. 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 Effects 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 Al – 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 been 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 – O2 ratio of 50% : 50% and annealed at 200 °C for 1 hour showed the lowest resistivity of 1.530 x 10-3 Ω. cm and the highest carrier concentration of +1.85 x 1022 cm-3.

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