Dual optimization of photoluminescence intensity and spectral position in porous silicon via factorial design and multivariate modeling

Abstract In this study, we conducted electrochemical anodization to fabricate porous silicon samples, varying electrolyte concentration, applied current, and anodization time. We employed a factorial design of experiments to analyze the impact of these parameters on both photoluminescence intensity and spectral position. Results revealed that electrolyte concentration and etching time significantly influenced photoluminescent intensity, with interactions between these factors being particularly noteworthy. Further analysis confirmed optimal conditions for maximizing photoluminescent intensity, and a second-degree polynomial fitting demonstrated the relationship between etching parameters and emission intensity. Additionally, multiple linear regression analysis of the spectral shift revealed that HF concentration was the dominant factor influencing emission wavelength, with higher concentrations producing significant redshifts that confirm the formation of larger silicon nanocrystallites through reduced quantum confinement effects. A mathematical model was developed to predict emission wavelength based on fabrication parameters and their interactions. Validation experiments corroborated the optimization process, leading to the fabrication of a sample with significantly enhanced photoluminescent emission at controlled wavelengths. Surface morphology analysis via scanning electron microscopy (SEM) revealed morphological variations influenced by etching parameters. While Raman spectroscopy measurements confirm the crystalline characteristics of the porous silicon layers and corroborate the mechanisms underlying the changes in photoluminescence behavior among the different samples. These findings provide valuable insights for the precise control of porous silicon fabrication parameters to achieve desired luminescent properties with tunable intensity and spectral position, advancing its potential for use in integrated photonic sensors, optical biosensing platforms, and biocompatible imaging systems.