Effect of The hydrogen dilution on the structural inhomogeneities of radiofrequency magnetron sputtered hydrogenated amorphous silicon films
A. Ben Othman1*, M. Daouahi2, J. Henocque3, K. Zellama3, H. Bouchriha1
1Faculté des Sciences de Tunis, Campus Universitaire,1060 Tunis, Tunisia
2Faculté des Sciences de Bizerte, 7021 Bizerte, Tunisia
3Laboratoire de Physique de la matière condensée, Faculté des Sciences d'Amiens, 33 rue Saint-Leu, 80039 Amiens, France
* Corresponding author. E-mail :email@example.com
Received : 02 May 2002; revised version accepted : 30 November 2002
The line width in the low frequency side of the transverse acoustic TA-like band (G(TA)) has been determined by Raman scattering measurements to study the structural inhomogeneities in hydrogenated amorphous silicon films (a-Si:H) elaborated by radiofrequency magnetron sputtering (RFMS) with different hydrogen dilution. These measurements are correlated with infrared absorption, optical transmission and photothermel deflection spectroscopy (PDS). The Raman and infrared results clearly indicate that G(TA) is strongly affected by the nature of hydrogen bonding configurations, essentially the (Si-H2) and (Si-H2)n polyhydride groups, which are known to favor the formation of structural inhomogeneties such as microvoids. This is corroborated by the good correlation observed on the one hand between G(TA) and the variation of both the static refractive index n0, which gives information about the density of material and the dispersion energy Ed, which measures the mean coordination number of Si atoms, and on the other hand between G(TA) and the changes in the Urbach energy E0, which is related to the structural disorder.
Keywords: Disordered systems; Semiconductors; Infrared and Raman spectra.