Complete photo-generated minority carriers quantum tunneling device under AM1.5 illumination is fabricated by depositing tin-doped indium oxide (ITO) on n-type silicon to form a structure of ITO/SiOx/n-Si heterojunction.The work function difference between ITO and n-Si materials essentially acts as the origin of built-in-field.Basing on the measured value of internal potential (Vbi=0.61 V) and high conversion efficiency (9.27%), we infer that this larger photo-generated holes tunneling oc-curs when a strong inversion layer at the c-Si surface appears.Also, the mixed electronic states in the ultra-thin intermediate region between ITO and n-Si play a defect-assisted tunneling.