A SYSTEMATIC INVESTIGATION OF THE ROLE OF MATERIAL PARAMETERS IN METASTABILITY OF HYDROGENATED AMORPHOUS-SILICON

In this work, the role of structural, electronic and optical parameter s of as-deposited amorphous silicon films in photoconductivity decay d uring light soaking was systematically investigated. Deposition temper ature was varied in the range 130-270-degrees-C, in order to obtain sa mples with different structural, optical and electronic properties. As a result, two degradation regimes were identified. At short illuminat ion times (within a few days in typical samples, and within a few hour s in the low quality samples), the material showed different tendency to degradation depending on the content of the SiH bond clusters. At l ong illumination times, in all the light soaked samples the photocondu ctivity decay followed the t-1/3 law. The measured photoconductivity d egradation was simulated starting from the bond-breaking model. The ob served correlation between the material structural parameters and the different tendencies to degradation is explained in terms of variation s of the Staebler-Wronski susceptibility.