ZnO thin film is a II-VI semiconductor which has large bandgap(~3.37 eV at R.T.) near UV range and large exciton binding energy(~60 meV). Because of these advantages, ZnO thin film is a good candidate for the UV light-emitting material. However, it is specially important to prevent the green emission for an application to the UV light-emitting material.
In this thesis, the corelation between the green emission and the non-stoichiometric composition of ZnO film was investigated in detail.
ZnO films were deposited on Si(100) substrate by reactive magnetron sputtering and annealed by rapid thermal annealing(RTA) at 800 $^\circ$C for 10 min in order to improve the crystallinities. At that time, the reactive sputtering gas ratio$(Ar:O_2)$ and the annealing atmosphere$(Ar, O_2)$ were varied to control the excess zinc contents of ZnO films. Wavelength dispersive spectroscopy and auger electron spectroscopy measurements showed that all the ZnO films had the compositions with excess zinc, and the photoluminescence spectra showed that all these films had small UV emission peaks and large green emission peaks. From these results, it was found that the green emissions were increased with increasing the Zn/O content ratios.
In order to decrease the Zn/O content ratio, Al ions were doped in the ZnO films by co-sputtering. And Al-doped ZnO films were also annealed by rapid thermal annealing(RTA) in Ar and $O_2$ atmosphere at 800 ℃ for 10 min. Before annealing and after annealing in Ar atmosphere, the Zn/O content ratios were decreased with increasing amount of Al-doping. However, In the cases of annealing in $O_2$ atmosphere, Al-doping effects were disappeared. As a result, the strongest UV emission peak was observed in 1.60 at% Al-doped ZnO film which was annealed in Ar atmosphere and the green emission peak was not observed.
