In this book,porous silicon preparing by electrochemical etching technique using different parameters such as silicon orientation ((100) & (111)), etching time (5, 10, 20 & 35 min), current density (10, 20, 30 & 40 mA/cm2) and HF concentration (15%, 20% & 30%). And next step of project was deposition of ZnO thin film on glass by spray pyrolysis technique from Zinc nitrite and study the effect of changing thickness of ZnO film (100, 200, 500 & 800 nm). And the final step of project consist deposition ZnO film on PS. The measurement refer that PS (100) gives the characteristics of nanoscale better than directional silicon (111) due to the crystal structure and the different in interaction between the HF electroyied and silicon. And The measurements of ZnO refer n-type semiconductor with hexagonal structure and the decreasing of ZnO thickness leads to increasing in energy gap due to decreasing in grain size. And when ZnO was deposited on PS the properties of both ZnO and PS will improved, like deceasing in crystal size and increasing in absorption of light with increasing in blue shift of PS and increasing in UV emission of ZnO film with incresing in rsistivty of heteojuntion