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Title: Role of hydrogen and oxygen on the band gap of silicon quantum dots
Authors: Ghoshal, S K
Gupta, Umesh
Gill, Karan Singh
Keywords: Quantum dots;Nanostructure;Confinement;Radiative recombination;Passivation photoluminescence;Pseudo-potential and HOMO-LUMO states
Issue Date: Mar-2005
Publisher: CSIR
IPC Code: H01L29/76
Abstract: A computer simulation using empirical pseudo-potential Hamiltonian has been performed to examine the variation of the band gap as a function of size and shape of small silicon (Si) quantum dots. It has been found that the gap decreases with increasing dot size. Furthermore, the band gap increases as much as 0.13 eV and 0.35 eV on passivating the surface of the dot with hydrogen and oxygen, respectively. So both quantum confinement and surface passivation determine the optical and electronic properties of Si quantum dots. Visible luminescence is probably due to radiative recombination of electrons and holes in the quantum confined nanostructures. The entire energy spectrum starting from the very low lying ground state to the very high lying excited states for silicon dots having 5, 8, 17 and 18 atoms has been investigated. The role of surface states on the gap energy as well as on the HOMO-LUMO states has also been examined. The results for the size dependence of the HOMO-LUMO gap and the wave functions for the bonding-anti-bonding states have been presented. The role of hydrogen and oxygen passivation on the confinement is also discussed.
Page(s): 188-191
ISSN: 0975-1041 (Online); 0019-5596 (Print)
Appears in Collections:IJPAP Vol.43(03) [March 2005]

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