Electrolyte composition dependence of the morphological and nanostructural features of porous silicon prepared by electrochemical anodic etching

• Published in: Metals and materials international Vol. 20; no. 6; pp. 1115 - 1121
• Main Authors: Kim, Hyo-Han, Son, Jong-Ick, Yun, Han-Sol, Cho, Nam-Hee
• Format: Journal Article
• Language: English
• Published: Springer The Korean Institute of Metals and Materials 01.11.2014; Springer Nature B.V; 대한금속·재료학회
• Subjects: Anodic; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electrolytes; Engineering Thermodynamics; Etching; Heat and Mass Transfer; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Nanocrystals; Nanostructure; Porous silicon; Processes; Silicon; Solid Mechanics; Wafers; 재료공학; anodization; raman spectroscopy; optical properties; morphology; semiconductors
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-014-6014-6

Porous silicon layers were formed by electrochemical anodic etching of p-type Si wafers. The electrostatic condition at the interface between the Si wafers and electrolytes was affected sensitively by the addition of isopropyl alcohol (IPA) in the etchant. As the IPA ratio was varied in the range of 0 to 75%, the ideality factor in the ln I-V relationships and the viscosity of the electrolytes changed from 27.2 to 16.0, and from 1.0 to 3.3 cp, respectively. The etched surface exhibited three different morphologies, such as ‘turtle-back’-, ‘column’-, and ‘mountain’-like structures depending on the electrolyte composition. The etched layers contained Si nanocrystallites, ~5.5 to ~2.6 nm in size, which exhibited photoluminescence features in the wavelength range, 733 to 624 nm. The variation of the band gap was determined by size of the nanocrystallites, whereas the nanostructural and morphological features were dependent on the IPA ratios of the etchants.