Photovoltaic properties of a novel stain etched porous silicon and its application in photosensitive devices

Photovoltaic (PV) properties of porous silicon (PS) produced by a novel sta in (chemical) etch solution based on fluoroboric (HBF4) acids are described for the first time. Sandwich structure devices in which semi-transparent c ontinuous gold electrodes are deposited on stain-etched PS have been observ ed to show high efficiency in photocurrent under visible light exposure. Ad ditionally, palladium (Pd) metallization of the nanoporous silicon (Si) has been performed using a new technique of electroless metal deposition (EMD) . The resulting sandwich devices show effective PV results, and with the us e of a nitrogen dye laser, the decay dynamics of the stain etched and elect roless metal-deposited PV devices have been characterized in the dark and u nder room light (RL). The PV decay times are observed to be of the order of microseconds, and vary with etch duration as well as with the details of t he EMD. Therefore, the metal-coated PS has great potential for application in solar cells and photodetectors, since efficient, stable and widely photo responsive devices can be produced. The process is also more cost-effective than current technologies since there is no necessity for antireflection c oatings, and there is also a reduction of device fabrication steps. (C) 200 1 Elsevier Science B.V. All rights reserved.