Density of states

of the pure evaporated amorphous silicon

 

R. N. Kre1* M. L. Mousse1, P. Y. Tchetche1, A. Boko1, P. A. Thomas2

1 Laboratoire de Physique Fondamentale et Appliquée, Université d’Abobo Adjamé, Côte d’Ivoire

2 Laboratoire de Physique des Solides, Université Pierre et Marie Curie, France

* Corresponding author: E-mail: kre_nguessan@yahoo.fr

Received: 14 August 2009; revised version accepted: 07 October 2010

 

Abstract

     From a model of density of electronic states and by the method of deconvolution, the optical absorption coefficient is calculated and compared to the experimental value of the optical absorption of the evaporated pure amorphous silicon thin films (a-Si) prepared in ultrahigh vacuum at room temperature and annealed at the temperature of 100 to 500 °C. The optical absorption coefficient has been obtained in the photon energy range of 0.5 to 2.5 eV with the transmission optical and photothermal deflection spectroscopy (PDS) measurements. The parameters deducted of the calculation are analyzed. The optical gap and the density of spins (dangling bonds) vary relatively little with disorder. An interrelationship is established between the density of defaults in the optical gap and the density of spins.

 

Keywords: Amorphous silicon evaporated; optical absorption; density of electronic states; absorption of Urbach.

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