Control of the crystallite size and passivation of defects in porous silicon by a novel method

Porous silicon films were prepared by lateral anodization of crystalline si licon in HF based solutions at different current densities. At an optimum c urrent density, passivation of the defects by an appropriate post-anodizati on treatment results in the significant enhancement in the photoluminescenc e (PL) efficiency. However, above the optimum current level, a phase is obt ained which shows significant broadening of the PL spectrum indicating the quantum wire size distribution, The degraded PL intensity in the treated sa mples is higher as compared to that for the as-anodized samples. Infrared v ibrational studies indicate that this enhancement is due to the H-passivati on of defects in the Si-pore interface, though the presence of hydrogen-ter minated silicon clusters cannot be ignored. Capacitance-voltage studies con cur well with the photoluminescence and infrared results. (C) 2001 Elsevier Science B.V. All rights reserved.