The application of UV detector in commerce and military are mainly focus on photomultiplier tube and UV detector based on silicon at present.However

the ponderosity

large energy consumption

and the attachment of the filters have certain limitation on the application of the photomultiplier tube as the UV detector.Recently

more attentions were paid on the solid wide gap semiconductor UV detector

especially for the potential application in solar blind region(220 nm to 280 nm) for the detection of the missile plume.The realization of GaN-based pn junction detector accelerated the development of UV detector in solar blind region.But the lack of the lattice mismatch substrate for the growth of GaN-based materials limited the rising of the devices efficiency.MgZnO appears to be an ideal material for the application of solar-blind photodetectors because it possesses unique figures of merit

such as availability of lattice-matched single-crystal substrates

tunable band-gap(3.3 to 7.8 eV)

relative low growth temperatures(100～750℃)

nontoxic

and low defect density.Moreover

it also has a good potential application in deep UV region.In this paper

we obtained the pure cubic phase MgZnO alloy with 255 nm absorption edge by LP-MOCVD

and realized a solar-blind MgZnO photodetector.The peak responsivity of the detector locates at 250 nm

and cutoff wavelength at 273 nm.The MgZnO films were deposited on sapphire substrate by LP-MOCVD.We select bis(η5-cyclopentadienyl) magnesium(Mg(C

5

H

5

)

2

) as Mg source

dimethylzinc as Zn source and high purity oxygen as Osource.The growth temperature was fixed at 450℃

the pressure in growth chamber is at 20 kPa.The growth time lasts for 1.5 hour

then the films were taken out from the growth chamber.Energy-dispersive X-ray spectrum(EDX) measurement showed that the composition of the films is Mg

0.52

Zn

0.48

O.Secondly

the interdigital Au electrodes were fabricated on 50 nm Au layer by conventional UV photolithography and wet etching.The interdigital fingers are 500 μm in length

5 μm in width

and the spacing between the fingers is 2 μm.The XRD patterns of MgZnO thin films show only one sharp and strong diffraction peak at 36.62°

which is assigned as cubic(111) orientation.The HMFM of the diffraction peak is only 0.16°

which shows the high quality of the thin film.The diffraction peak indicates that the sample has a metastable cubic phase without phase separation.The absorption spectrum shows that the band gap of the Mg

0.52

Zn

0.48

Ois at 4.86 eV(255 nm)

which has step in the phase region reported in literature(4.0～5.0 eV).As well known

the low growth temperature is beneficial to the cubic MgZnO film with large Mg composition

due to that the metastable state is more easily formed at low growth temperature.The responsivity of the detector exhibits the peak energy at 250 nm and cutoff wavelength at 273 nm

which satisfies for the wavelength-need of the missile flume detection in response wavelength region.