Influence of Etching Current Density on Visible Electroluminescence from Porous n‐Si under Cathodic Bias

Visible electroluminescence (EL) from cathodically biased n‐Si in an electrolyte solution containing has been studied. EL from the porous n‐Si samples fabricated by photoelectrochemical etching over a wide range of current densities shows both blueshift and peak broadening with increasing , which can be attributed to the progressive participation of more silicon hydride species, , with larger n in the emitting progress. Based on analysis of spectral changes and resolution of the EL peak into components, a revised mechanism of the EL, where silicon hydrides are considered to donate electrons to sulfate radical anions, is proposed. EL is produced by recombination of the resulting radical, , with an accumulated electron in the conduction band. The radicals would lead to competing reactions that strip off hydrogens from the surface silicon hydrides. with larger n is subject to the earlier EL. © 1999 The Electrochemical Society. All rights reserved.