Comparative studies of the influence of hydrogen incorporation on the electronic properties of a-Ge:H films prepared by two different techniques

• Published in: Canadian journal of physics Vol. 77; no. 9; pp. 659 - 666
• Main Authors: Bouizem, Y, Sib, J D, Chahed, L, Theye, M L
• Format: Journal Article
• Language: English
• Published: Ottawa Canadian Science Publishing NRC Research Press 01.09.1999
• Subjects: Comparative studies; Electrons; Germanium; Hydrogen; Optics; Physics; Thin films
• ISSN: 0008-4204; 1208-6045
• DOI: 10.1139/cjp-77-9-659

We present the results of a detailed investigation of hydrogen incorporation and optical absorption in the 0.6-1.3 eV range for two series of hydrogenated amorphous germanium films (a-Ge:H) deposited by reactive sputtering (series A) and by plasma-enhanced chemical vapor deposition from germane (series B). Our results clearly show that the series A samples are characterized by a larger bonded hydrogen concentration (C@@dH@), a more rapid gap variation with increasing C@@dH@, a smaller refractive index, and a lower density than the series B samples. We also compare in detail the energy distribution of the localized states in the pseudo-gap and the deep-defect states density as deduced from a decomposition of the optical absorption spectra based on a theoretical model for the gap states density in amorphous tetracoordinated semiconductors.