Positional dependence of optical absorption in silicon nanostructure

We present a theoretical study of the optical absorption process of a 9 x 9 Si quantum wire. We calculate the imaginary part of the dielectric constant epsilon (2) and the contribution to epsilon (2) due to three Si atoms located in different positions using the non-orthogonal tight-binding method. From these calculations, we clearly find for the first time that the optical absorption below 3.4 eV tends to occur in the inner region of the 9 x 9 Si quantum wire. (C) 2001 Elsevier Science B.V. All rights reserved.