• Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/boms/028/03/0219-0225

    • Keywords

       

      Porous silicon; Raman scattering; photoluminescence; quantum confinement; high resolution transmission electron microscopy.

    • Abstract

       

      Raman scattering and photoluminescence (PL) measurements on (100) oriented 𝑛-type crystalline silicon (𝑐-Si) and porous silicon (PS) samples were carried out. PS samples were prepared by anodic etching of 𝑐-Si under the illumination of light for different etching times of 30, 60 and 90 min. Raman scattering from the optical phonon in PS showed the redshift of the phonon frequency, broadening and increased asymmetry of the Raman mode on increasing the etching time. Using the phonon confinement model, the average diameter of Si nanocrystallites has been estimated as 2.9, 2.6 and 2.3 nm for 30, 60 and 90 min samples, respectively. Similar size of Si crystallites has been confirmed from the high resolution transmission electron microscopy (HRTEM). Using 2TO phonon mode intensity, we conjectured that the disordered Si region around the pores present in 30 min PS dissolved on etching for 90 min. The photoluminescence (PL) from PS increased in intensity and blue shifted with etching time from 2.1–2.3 eV. Blue shifting of PL is consistent with quantum confinement of electron in Si nanocrystallites and their sizes are estimated as 2.4, 2.3 and 2.1 nm for 30, 60 and 90 min PS, respectively which are smaller than the Raman estimated sizes due to temperature effect. Unambiguous dominance of quantum confinement effect is reported in these PS samples.

    • Author Affiliations

       

      R Prabakaran1 R Kesavamoorthy2 Alok Singh3

      1. Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
      2. Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
      3. Department of Physics, Loyola College, Chennai 600 034, India
    • Dates

       

© 2017-2019 Indian Academy of Sciences, Bengaluru.