NITROGEN IN THE AMORPHOUS-GERMANIUM NETWORK - FROM HIGH DILUTION TO THE ALLOY PHASE

In this work experimental data referring to the structural and optoelectronic characteristics of amorphous-germanium-nitrogen thin films are presented and discussed. The nitrogen content of the a-Ge: N samples, deposited by the rf-sputtering technique in an Ar+N2 atmosphere, was allowed to vary from typical impurity levels (less than 0.5 at. %) up to around 35 at. %. The material properties change depending on the nitrogen concentration, determined from a deuteron-induced nuclear reaction. The likely mechanisms of nitrogen incorporation into the solid phase are discussed, as well as the influence of the nitrogen content on the transport and optical properties of the films. A proportionality constant relating the total nitrogen concentration in the solid phase and the integrated absorption of the in-plane stretching vibration mode of the Ge-N dipole has been determined. It has been found that a close analogy exists between the general properties of a-Ge:N alloys and those measured in amorphous-silicon-nitrogen alloys.