PRIMARY LUMINESCENCE OF POROUS SILICON

This paper discusses the spectra, the luminescence kinetics, and the l uminescence-degradation kinetics under the action of light (luminescen ce fatigue) of porous silicon. The experiments were carried out on hig hly uniform, large-area samples obtained by ion-stimulated chemical et ching. The large surface area of the samples made it possible to do th e recording in the continuous surface-scanning regime and thereby to r ecord spectra completely free from the effect of luminescence-fatigue processes. It is shown that the spectral shift of the spectra recorded in the usual way is not small relative to the primary spectra, as is usually assumed, but is comparable in order of magnitude with the widt h of the luminescence band. The lux-watt characteristics of the lumine scence are measured in the surface-scanning regime. For small excitati on intensities, a recombination level that exceeds unity is detected. This indicates that not only excitons but also separate carriers parti cipate in the recombination processes. (C) 1996 American Institute of Physics.