Abstract: In order to study effect of porous silicon (PS) porosity on the optical and electrical properties of ZnS/PS composites,ZnS film was deposited on PS substrates with different porosities by means of pulsed laser deposition.The crystalline structure,surface morphology of ZnS film on PS substrates and optical,electrical properties of ZnS/PS composites were studied by means of X-ray diffraction,scanning electron microscope,photoluminescence (PL) spectra and Ⅰ-Ⅴ characteristics respectively.The results show that ZnS film deposited on PS substrates have a crystalline structure of cubic phase growing in preferred orientation along β-ZnS(111)direction.With the increase of PS substrate porosity,the intensity of diffraction peak of ZnS film decreases and some voids and cracks appears in ZnS film.In the PL spectra of ZnS/PS composites,the PL peak of PS has a blue shift compared with original PS.The larger the porosity of PS substrate,the greater the blue shift.With the increase of PS substrate porosity,a new green light emission at about 550nm appears which is attributed to defect-center luminescence of ZnS.The blue,green emission of ZnS combined with the red emission of PS,ZnS/PS composites exhibit intense while light emission.Based on the Ⅰ-Ⅴ characteristics,ZnS/PS heterojunctions exhibit the similar rectifying properties to the common diode. Under forward bias conditions,the current density is large and the voltage drop is small,on the contrary,under reverse bias conditions,the current density is nearly zero.With the increase of PS substrate porosity,the forward current increases.The research results lay a foundation for the realization of solid state white light emission devices.