SEM and HRTEM study of porous silicon—relationship between fabrication, morphology and optical properties

• Published in: Applied surface science Vol. 238; no. 1-4; pp. 169 - 174
• Main Authors: Dian, J., Macek, A., Nižňanský, D., Němec, I., Vrkoslav, V., Chvojka, T., Jelı́nek, I.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2004; Elsevier Science
• Subjects: Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; High resolution transmission electron microscopy; Materials science; Nanocrystalline materials; Nanocrystals and nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Photoluminescence; Physics; Porous silicon; Quantum confinement; Scanning electron microscopy; Structure of solids and liquids; crystallography; 61.46.+w; Quantum confinement; 68.37.Lp; Scanning electron microscopy; 68.37.Hk; 81.07.Bc; Photoluminescence; 78.67.Bf; High resolution transmission electron microscopy; Porous silicon; Porous materials; Nanoparticles; Transmission electron microscopy; 81.07.Bc Porous silicon; Fabrication structure relation; Silicon
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2004.05.218

We studied the dependence of porous silicon (PS) morphology on fabrication conditions and the link between morphology, porosity and optical properties. P-type (100) silicon wafers with resistivity of 10Ωcm were electrochemically etched in a HF:ethanol:water mixture at various HF concentrations and current densities. Porosity and thickness of the samples were determined gravimetrically. Detailed information about evolution of porous silicon layer morphology with variation of preparation conditions was obtained by scanning electron microscope (SEM), the presence of silicon nanoparticles was confirmed by high resolution transmission electron microscopy. Decrease of the mean size of silicon nanoparticles with increasing porous silicon porosity was revealed in a monotonous blue shift of photoluminescence (PL) maximum in room temperature photoluminescence spectra of studied samples. This blue shift is consistent with quantum confinement model of photoluminescence mechanism. We observed that total porosity of porous films cannot fully explain observed photoluminescence behavior and correct interpretation of the blue shift of photoluminescence spectra requires detailed knowledge of porous silicon morphology.