Comparison of transport and defects properties in hydrogenated polymorphous and amorphous silicon

Due to its specific microstructure with nanocrystals embedded in an amorphous matrix, polymorphous silicon (pm-Si:H) has been shown to present interesting properties for large area electronic applications. In particular, this material exhibits a lower density of localized gap states and better transport properties than standard amorphous silicon (a-Si:H) after light-soaking. In this paper, we focus our attention on the comparison of electronic transport and defect properties of both materials. The temperature-dependent photocurrent is similar to that of high-quality a-Si:H: it shows thermal quenching in the temperature range around 250 K and becomes temperature-independent at temperatures smaller than about 40 K. Electrically detected magnetic resonance (EDMR) under illumination was performed from 296 K down to 10 K to cover a very wide temperature range wherein the photocurrent is dominated either by free electrons in the band (higher temperatures) or by energy-loss hopping (lower temperatures). The comparison with the EDMR properties of a-Si:H and μc-Si:H assists in the interpretation of the results, thereby clarifying the influence of the incorporated nanocrystals on the recombination physics in pm-Si:H.