The transport properties in iron-passivated porous silicon (IPS) with stable optical properties were studied, Experimental results make plausible that the electrons are injected into IPS by tunneling at the metal/IPS interface, It has also been found that the transport properties in IPS are dominated by the single-crystal silicon (sc-Si) substrate layer, which leads to the low electroluminescence (EL) efficiency. Although the transport of IPS is dominated by the sc-Si substrate layer at room temperature, the porous layer does contribute to conduction when it is irradiated with 300 nm ultraviolet light. This effect is ascribed to the contribution of the electrons photoexcited to the conduction band in the porous layer. (C) 2002 Published by Elsevier Science B.V.