The promotion of silicon from being the key substrate material for microelectronic devices to a potential light emitter has emerged as a consequence of the possibility to reduce its dimensionality by different techniques. In this regard nanostructured porous silicon (PS) drew formidable attention because of its strong room temperature photoluminescence (PL) in the visible region and due to its very simple and Si-IC technology compatible fabrication process. However, fabrication of PS with uniform pore and particle size distribution, which is essential for device application, is still an unresolved problem. We report a technique for non destructive estimation of porosity of the PS samples by measuring voltage across the electrodes of the electrochemical formation bath. A uniformity factor was defined in terms of formation current density (J), critical current density (J_PS) and measured porosity (P_m). The factors affecting P_m was linked to the voltage across the electrodes using Bruggeman’s effective medium approximation (EMA) that included electrical conductivities of the electrolyte and the sample. An attempt was made to optimally design a set of parameters that can potentially produce PS with narrow band pore and particle sizes. The sensitive and nonlinear dependence of PS morphology on the formation and post-formation parameters and their wide range demanded a non-classical optimization technique. A multivariate, genetic algorithm (GA) based optimization of the uniformity factor was found suitable for determination of the range of the controllable variables and to develop a guide strategy for experiments. A series of experiments were performed on p-type Si substrates using the GA evolved parameters. Porosity was measured by conventional destructive and developed nondestructive method. The results provided important insight in designing uniform PS nanostructures.

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