We present the results of UV photodetectors fabricated on ZnO epitaxial films grown on

c

-plane sapphire substrates by plasma assisted MOCVD.The ZnO films with single

c

-axis orientation and high resistivity are obtained.With plasma apparatus

we also obtain high resistivity ZnO films doped with N.Considering the high photo-conductive characteristics of ZnO

and characteristics of device with MSM structute

such as high responsivity

high speed

little change with bias

simple fabrication technic

easy for monolithic integration

we fabricate the ZnO UV photodetector.The size of the device is 80μm×100μm

the electrode is interdigital.Measurements are performed using a 500 W Xe-arc lamp as light source.Based on the

I-V

characteristics of ZnO MSM IDT devices

we can conclude that the dark current and illuminated current of the photodetector linearly increase with the increase of the bias.The curve of the spectra-photoresponse of the IDT photodetector indicates that the detector is in response to the ultraviolet wave range and that the peak value is about 375 nm.