Effect of etching mode on the porosity of layers and photoluminescence in multilayer porous silicon

Subject of study . Multilayer samples of porous silicon produced using a variety of electrochemical etching process parameters were studied. Goal of work . An experimental study of production techniques for multilayer porous silicon was conducted, and techniques for fine-tuning the volume and surface properties for use in nanoelectronic devices were developed. Method . The surface morphology was studied by atomic force microscopy and scanning electron microscopy. The surface-layer porosity was studied using X-ray reflectometry. The electron structure of the surface was studied using ultrasoft X-ray emission spectroscopy. The optical properties were determined using photoluminescence spectra. Main results . It was found that stepwise increases in electrochemical anodizing current through a monocrystalline silicon substrate produce multilayer structures in which the layers have different morphologies, surface compositions, and porosity values. Photoluminescence was found to be determined primarily by the composition of the top layer. The effects of gradually increasing the current density while holding the overall etching time constant are also discussed in detail. Practical significance . The research results for the effect of etching mode on porous-silicon morphology and optical properties will be used for the development of nanoelectronic devices based on porous structures.