As an important candidate material for photoelectric devices such as ultraviolet detector

thin Mg

x

Zn

1-

x

O films (MZO) have been recently given extensive attention. Most studies have been focused on changing target compositions to prepare MZO with absorption edge in the solar-blind region (220~280 nm). However

the mix phases of hexagonal ZnO and cubic MgO appear when the Mg concentration increases to certain percentage. For different growing technologies and parameters

different limits of Mg concentration have been reported to keep MZO single hexagonal phase. Besides

the Mg content in the prepared thin films often deviates from the targets according to most studies. In this paper

a series of thin MZO films were prepared with different growing pressure on the Si(111) and quartz substrates by using Mg

0.2

Zn

0.8

O target and pulsed laser deposition (PLD) method in order to adjust the Mg content in the prepared MZO samples. The crystal structures

micro-morphologies and optical properties were characterized by X-ray diffraction (XRD)

scanning electron microscopy (SEM)

X-ray energy dispersion spectra (EDS) and ultraviolet-visible absorption spectra. The EDS results showed that the Mg concentrations in the prepared samples change from 44.5% to 48.5% with the growing pressure from 5.210

-4

Pa to 0.3 Pa

much higher than that in the target. But all the thin films still show single hexagonal phase according to the XRD results. We suggested that the increase of Mg content in the thin films is due to the stronger binding force of Mg-O compared to Zn-O in the oxygen-deficient growing environment. The band-gap of the thin films increases from 3.83 eV to 4.05 eV with the increasing Mg content

which can be estimated from the transmittance spectra. Among all the MZO samples

the 48.5% Mg sample has the shortest absorption edge which is close to 300 nm

quite near the solar-blind region. This work would be helpful for the preparation of solar-bind thin MZO films with single phase.