The current study aimed to produce Si nanostructures ultra-high sensitivity photodetector by photo electrochemical method. The effect of changing some factors on the formation of porous silicon has been studied. The etching time has been changed using a photoelectrochemical procedure with a Halogen lamp. Relying on crystalline silicon n-type wafers (100) with resistivity of 0.1–100 Ω.cm, porous silicon layers were developed. Etching solution containing 16% HF was used at different etching times of (6,9,12,15,18, and 21) min. and 20 mA/cm2 current density. The properties of the (J-V) and (Jph-V) in both darkness and photocurrent density, were used in demonstrating PS. When the crystal size is around a nanometer, XRD broadening of PS nanostructures increased as the crystallite size dropped, with the peaks becoming more widened. The peak of the PL spectrum changes a little on the high-energy side, indicating the presence of quantum confinement effect in porous silicon. While analyzing SEM data, the pores have cylindrical shape is a consequence of increasing the morphological characteristics average diameter. When compared to bulk silicon reflectivity, the observed significantly – lower PS surface Reflectance, demonstrated the porous silicon layer's thinness. In responsivity, two peaks appeared. The first one reaction peak was absorbed in the depletion region, at 500 nm of the Al-PS. While the second peak absorption was in the PS-c-Si depletion area at 500–600 nm and on 21 min etching time, where a maximum quantum efficiency of 83% was obtained.