Open Access Nano Express

Optical absorption of dilute nitride alloys using self-consistent Green’s function method

Masoud Seifikar12*, Eoin P O’Reilly12 and Stephen Fahy12

Author Affiliations

1 Tyndall National Institute, Lee Maltings, Dyke Parade, Cork, Ireland

2 Department of Physics, University College Cork, Cork, Ireland

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Nanoscale Research Letters 2014, 9:51  doi:10.1186/1556-276X-9-51

Published: 29 January 2014

Abstract

We have calculated the optical absorption for InGaNAs and GaNSb using the band anticrossing (BAC) model and a self-consistent Green’s function (SCGF) method. In the BAC model, we include the interaction of isolated and pair N levels with the host matrix conduction and valence bands. In the SCGF approach, we include a full distribution of N states, with non-parabolic conduction and light-hole bands, and parabolic heavy-hole and spin-split-off bands. The comparison with experiments shows that the first model accounts for many features of the absorption spectrum in InGaNAs; including the full distribution of N states improves this agreement. Our calculated absorption spectra for GaNSb alloys predict the band edges correctly but show more features than are seen experimentally. This suggests the presence of more disorder in GaNSb alloys in comparison with InGaNAs.

Keywords:
Dilute nitride semiconductors; Self-consistent Green’s function; Optical absorption; Band anticrossing model