Visible Electroluminescence from n‐Type Porous Silicon/Electrolyte Solution Interfaces: Time‐Dependent Electroluminescence Spectra

Abstract

Visible electroluminescence (EL) from n-type porous silicon (n-PS) in an electrolyte solution containing S 2 O 8 2Ϫ was investigated by potential-sweep and potential-step methods. Potential sweep measurements showed that both the cathodic current and EL intensity increased and the EL spectra blue-shifted as the potential became negative. These characteristics were further studied by the potential-step method. Immediately after the potential was stepped to a negative value, the cathodic current began to flow and EL was observed. The EL intensity then increased but the cathodic current decreased with time. The rate of the increase in the EL intensity depended not on the S 2 O 8 2Ϫ concentrations but on the applied negative potentials. Time-resolved EL spectra measurements showed that the EL spectrum was blue-shifted with time even when a constant negative potential was applied to n-PS. These results were explained by considering that the emission site was changed from larger-sized Si crystallites to smaller-sized ones in the n-PS layer with time.

Fabrication of ZnS/Porous Silicon Composite and Its Enhancement of Photoluminescence

“…Therefore, the PSi can emit PL in spite of being an indirect semiconductor because there is nanocrystalline Si in the porous layer [15], and the band gap depends on the particle size of the nanocrystalline Si in accord with the quantum size effect [16][17][18]. Crystalline Si does not show PL because of the quantum band structure having an indirect band gap of about 1.1 eV and a small exciton binding energy (below 15 meV) [19].…”

Developments in Luminescence and Display Materials Over the Last 100 Years as Reflected in Electrochemical Society Publications

“…Further work on luminescence in porous silicon was published in the Journal in 1999. This included a paper by Noguchi et al, 197 which described the visible EL from n-type porous silicon in an electrolyte solution. Time-resolved EL spectra measurements showed that the EL spectrum was blue-shifted with time.…”