As one of potential photoelectric material

zinc oxide attracted a lot of attentions recently. Such as

its wide band gap (3.37 eV) and high excitonic binding energy of 60 meV make ZnO as a good candidate for developing short wavelength optical devices. Furthermore

the p-doping ZnO can be produced and the p-n structure of ZnO can be formed on the silicon substrate

both of characteristics make ZnO to be compatible with Si-based integrated circuits. Hence

ZnO film has wider application in opto-electronic industries.ZnO films can be easily prepared by reactive sputtering. techniques However

the surface state which caused by damages of bulk silicon surface and lattice mismatch impurity which contaminated in fabrication procedure can produce the level of surface state and deep level in heterojunction. Those levels affect the carries a lot.Generally the level formed by defects can reduce illuminant efficiency

producing non-radiation recombined

but deep level can also become efficient illuminant centre using wide band gap materials. So it is deserved to study deeply of the behavior of ZnO/p-Si heterojunction interface state. The high frequency

C-V

character can be used to measure the charge of space charge region varied with the voltage variation

this effect of capacitance can be described by differential capacitance. The

C-V

measurement supplied an important way to research the characteristics of heterojunction. With the help of the measuring

C-V

and

I-V

character

we can easily obtain the evidence that interface impurity state and defects in ZnO:Al/p-Si interface can have largely influence on electricity property of the heterojunction. We also found it was very useful to reduce the interface state (using) annealing procedure. It was clearly to see that the sample annealed in 800℃ had the larger illuminant efficiency.Whether annealed or not

the sample grown by RF sputtering technique can form an abrupt heterojunction

but the character of potential was not the same. As a large number of deep level and surface state level were in interfaces

the

C-V

curve of sample which was not annealed was aberrance and the

I-V

curve was exponential with reversing bias voltage. In condition of annealing under 800℃

we can observe the influence of interface state was eliminated

and improved rectifying characteristic of heterojunction.