[en] Silicon is used almost to the exclusion of all other materials in semiconductor electronics. However, it suffers from the limitation that it is an indirect band gap material and does not emit light efficiently. Since the advent of fiber-bound data transmission, there has been considerable interest in the modification of silicon to make it light emitting. Various ways of modification have been suggested. These include porous silicon and spark processed silicon. Both methods are very simple techniques, that produce low dimensional silicon structures, which are believed to be responsible for the better light emitting properties. However, because both techniques are carried out in air or in a liquid environment, they both change the composition and introduce impurities in to the silicon. Thus it is important to determine the composition of these materials in order to establish whether there is a relationship between composition and light emitting properties. Spark processed silicon, like porous silicon, is very easy to produce but has the advantage over the latter that it is structurally and chemically more stable. Because of this diodes can easily be produced by depositing a conducting layer on top of the spark processed samples. Diodes produced in this way turn out to have differences in their performance depending on the material of the conductive layer. Diodes with silver and copper conducting layers were produced and their compositions were measured using ion beam analysis (IBA) techniques. (authors)