Herein, we investigated structural and electrical properties of ultrasonic spray pyrolyzed ZnO thin films (ZnO (USP)) deposited on radio frequency sputtered ZnO nanocolumns (ZnO(Seed)) under various oxygen atmosphere on p-Si substrates. X-ray diffraction data of the samples showed that the samples had a hexagonal structure with a strong (002) preferred orientation. The grain size of ZnO(USP) samples prepared on the seed layer sputtered in 25% and 50% oxygen atmosphere decreased and surface morphology was nanopebbles. ZnO samples prepared on the seed layers exhibited sharp and predominant ultraviolet luminescence at approximately 380 nm. The current-voltage characteristics of the n-ZnO(USP)/n-ZnO(seed)/p-Si heterojunctions were significantly affected by the seed layer preparation conditions. Backward diode behavior was observed for the n-ZnO(USP)/n-ZnO (seed)/p-Si heterojunctions with high donor concentration, in which the seed layers prepared in 100% and 75% argon atmosphere. The carrier concentration value was decreased for the films with the seed layer, obtained at higher oxygen content in the sputtering atmosphere.