Joint density of states of nanostructures: an application to porous silicon

In this work the electronic interband transitions in porous silicon are studied. The calculation is performed using a supercell model with a tight‐binding Hamiltonian, where an atomic‐orbital sp3s* basis set is used. The pores are modelled as empty columns, digged in a crystalline silicon structure, and then passivated with hydrogen atoms. The effects of disorder in porous silicon are considered by introducing a random perturbative potential into the Hamiltonian, which produces non‐vertical interband transitions in the reciprocal space. Such transitions occur in an interval inversely proportional to the electronic localization length. Finally, a comparative analysis of the optical absorption coefficient is performed by means of vertical, non‐vertical transition, and the joint density of states (JDOS). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)