We report on the antireflection property of AlOx, film deposited on n-ZnO/p-Si photodiode and also report on the photoelectric properties of the diode fabricated for detecting both ultraviolet (UV) and visible photons. Optical reflectance spectra obtained from AlOx/ZnO/Si (100) samples exhibited that the reflectance in UV range over the bandgap of ZnO is lower than that in visible range below the bandgap. As characterized by current-voltage (I-V) measurements in the photon range of 310-670 nm, our photodiodes exposed to UV photons show a linear photocurrent increase with reverse bias while under visible photons the photocurrent rapidly rises but saturates from similar to5 V on. Our diodes exhibit 0.48 A/W of strong responsivity at 310 nm and 0.2 A/W at 670 nm under a reverse bias of 30 V but show weak responses near 380 nm which is the wavelength corresponding to the bandgap of ZnO. (C) 2003 Elsevier B.V., All rights reserved.