The Ag-BaO are composite thin films in which metallic nanoparticles are embedded in semiconductor matrixes.It has an ultrafast response time of photoemission and can be used for detecting ultrashort duration laser pulses.After applying a vertical electric field on the surface of thin films

the efficiency of photoemission can be increased.The Ag-BaO thin films were prepared by vacuum evaporation.The total thickness of thin film was 200～300nm

but the thickness of the Ag-BaO thin films was 100～140nm which got rid of the thickness of the above and bottom electrodes.The thin films presented obvious enhanced photoabsorption in the near ultraviolet region when a vertical electric field was applied to the surface of the thin films.The photoabsorption at wavelength λ=303nm was increased by 6.5% and 18% stimulated by vertical voltage 15V and 30V on the surface

respectively.The reason of enhanced photoabsorption is that the energy band of thin film becomes oblique and split under the application of a strong electric field.Through absorbing the energy of photons

excited electrons trend to increase the probability for tunneling in oblique energy band and for transition between split energy levels.