Arturo Ramírez-Porras

arXiv2026

Multiscale Correlation of Morphological, Chemical, and Optical Properties in p-Type Porous Silicon

We report a systematic study of the correlations among electrochemical processing conditions and the morphological, chemical, and optical properties of porous silicon (pSi). Twenty pSi samples were fabricated from boron-doped (100) crystalline silicon by varying current density, etching time, and hydrofluoric-acid concentration. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and photoluminescence were used to characterize the resulting structures. The two-dimensional porosity varied only moderately, whereas porous-layer thickness increased with etching time and current density. The silicon oxide to silicon hydride ratio showed comparatively small variations. Corrected photoluminescence spectra were fitted with a four-component quantum-wire/quantum-dot model including localized surface-state transitions. The extracted quantum-wire and quantum-dot dimensions decreased systematically with increasing current density, while the photoluminescence maximum under 375 nm excitation showed no clear monotonic dependence on processing conditions. The results demonstrate that no single descriptor adequately captures the multiscale behavior of porous silicon.

cond-mat.mtrl-sci↗

arXiv2025

On the Photoluminescence Theory in Nanocrystalline Silicon: A New Improvement

Silicon has long been the foundational semiconductor material for a broad range of electronic devices, owing to its numerous advantages: wide natural availability, ease of synthesis in both crystalline and amorphous forms, and relatively low production cost. However, despite these benefits, silicon is inherently limited in the field of optoelectronics due to its indirect bandgap, which results in low quantum efficiency for light emission, typically in the infrared region. One promising strategy to address this limitation is the development of nanocrystalline silicon, which consists of low-dimensional nanostructures such as quantum wires (QWs) and quantum dots (QDs). These structures exhibit enhanced photoluminescence and electroluminescence, primarily due to quantum confinement of excitons within the conduction and valence bands, leading to significantly improved quantum efficiency. Although research into these processes has spanned several decades, a definitive consensus on the mechanisms underlying photoluminescent emission in nanocrystalline silicon remains elusive. This work reviews two leading theoretical models proposed to explain this phenomenon and introduces a new, more comprehensive model that may provide a deeper and more accurate understanding of photoluminescence in nanocrystalline silicon. The new theory is applied in a case study.

cond-mat.mtrl-sci↗