Pm. Derlet et al., AN INVESTIGATION OF THE POROUS SILICON OPTICAL-ABSORPTION POWER-LAW NEAR THE BAND-EDGE, Journal of physics. Condensed matter, 7(12), 1995, pp. 2507-2523
A theoretical investigation of the absorption coefficient of p-type do
ped porous silicon near the band edge is presented. We assume that the
absorption coefficient is constructed by taking an average over a dis
tribution (in terms of band gap) of absorption coefficients of individ
ual crystallites. Exploiting physics fundamental to the crystallite op
tical absorption process, we derive the relation between the absorptio
n coefficient and the averaged conduction density of states near the b
and edge for porous silicon. By postulating a specific form for the ef
fective conduction density of states we find excellent agreement with
recent optical absorption data for p-type doped porous silicon. We att
empt to explain the basis for this postulate phenomenologically by sug
gesting a certain large-scale behaviour of the particle size distribut
ion. The implication of further experimental verification will be disc
ussed.