ZnO is surely one of the most promising semiconductor materials in the future in the fields of opto-electronics

photochemistry and microelectronics

etc.

Many techniques such as radio frequency or direct current sputtering

ion plating and chemical vapor deposition have been employed to prepare ZnO thin films

the sputtering process is the most promising method for depositing ZnO films among these processes.The advanta-ges of sputtering are the simple apparatus

high deposition rate

low substrate temperature

good surface flatness

transparency and dense layer formation.The properties of ZnO films are generally affected by the preparation conditions

such as deposition methods

working pressure

and the types of substrates

etc.

In order to do a systematic research about effect of the oxygen/argon ratio on the microstrueture and the optical absorption properties

ZnO thin films with c-axis preferred orientation were prepared on glass substrates by r.f.coreactive magnetron sputtering technique

influence of oxygen partial pressure on the microstructure and optical absorption properties of ZnO thin films were studied by X-ray diffraction(XRD) and UV-Vis absorption spectra. The XRD patterns of the five ZnO samples were measured by XRD equipment.The figure which embo-died the relation of Full Width at Half Maximum (FWHM) of the diffraction peak and grain size of the five samples as a function of oxygen partial pressure was given out.The XRD patterns and the figure showed that relative intensity of (002) diffraction peak of the samples increased when the oxygen/argon ratio was under 14:10

but it then decreased when the oxygen/argon ratio near 18:10.The figure showed that the FWHM decreased and the grain size of the samples increased when the oxygen/argon ratio was under 6:10

but it then represented opposite trend when the oxygen/argon ratio was bigger than 6:10

and the sample which were prepared at the oxygen to argon ratio of 6:10 had the biggest crystal grain size and the least FWHM.The results showed that when the working pressure was kept in constant

the growth behavior of the ZnO thin film was mainly decided by the density of oxygen in the space where the sample was deposited

and the crystallization of the ZnO thin films was promoted by desirable oxygen partial pressure.In addition

absorption spectra of the five ZnO samples deposited at different oxygen partial pressures have been measured at room temperature

the films possessed a transmittance of about 90% in the visible region.The figure embodied (

αhv

)

2

versus hv of ZnO films grown at different oxygen partial pressures was given out

too.It was concluded that with the increase of oxygen partial pressure

the band gap exhibited different values.Furthermore

theoretical calculations of the optical band gap were carried out using the quantum confinement model

the theoretical calculated values are in good agreement with the extrapolated results.It indicated that the change of band gap had great relationship with quantum confinement effect when the ZnO nanocrystals was small.The conclusion above is of great importance in preparing high-quality ZnO thin films

improving transmittance

accommodating absorption edge of ZnO films when it is used as transparent conducting layer.