ANALYSIS OF THE INTERBAND-TRANSITIONS IN POROUS SILICON

Porous silicon (PS) presents interesting phenomena such as efficient l uminescence and a peculiar transport of carriers. Due to its possible optoelectronic applications, it is important to calculate the dielectr ic function from interband optical transitions in PS to include quantu m effects. In this work, we apply a supercell model for PS within an s p(3)s tight-binding technique, to analyze the effects of pores on the above-mentioned transitions. The polarized light absorption is studie d by observing the oscillator strength behavior within two different s chemes, which are applied and compared. We have found a significant en largement of the optically active zone in the k-space, due to the loca lization of the wave function. The calculated dielectric functions for crystalline silicon and PS are compared with experimental results, gi ving the correct energy range and shape. (C) 1998 Elsevier Science B.V . All rights reserved.