Voltage-controlled spectral shift of porous silicon electroluminescence

In this paper, it is reported that the electroluminescence (EL) of porous silicon shows a reversible spectral shift as large as 270 nm for an external bias variation of 0.6 V. This electroluminescence is obtained upon cathodic polarization of lightly doped n-type porous silicon in contact with aqueous persulphate solutions. The study of the EL behavior as a function of the external voltage and the persulphate ion concentration proves that while the amplitude of the EL is proportional to the intensity of the exchanged current, the spectral position is only determined by the applied voltage.