It was recalled that, when thin films were deposited by means of plasma-enhanced chemical vapour deposition under conditions close to those required for the formation of powder, a new type of material (polymorphous Si) was obtained. The opto-electronic and stability properties of polymorphous films which were deposited from mixtures of silane and H, at total gas pressures ranging from 0.8 to 1.6Torr. Characterization of as-deposited polymorphous films showed that the best samples exhibited enhanced transport properties. Thus, the quantum-efficiency mobility-lifetime product was increased by a factor of 200 to 700, as compared with that found for amorphous hydrogenated Si under the same conditions. This was related to a lower density of deep states. The creation kinetics of defects under 0.67W/cm2 of white-light illumination, and at 100C, were studied. The polymorphous samples exhibited faster creation kinetics, as well as annealing, of metastable defects than did amorphous hydrogenated samples. The enhanced transport properties and better stability were linked to the structure of polymorphous material; with ordered Si nano-particles embedded in an amorphous matrix.

Some Electronic and Metastability Properties of a New Nanostructured Material - Hydrogenated Polymorphous Silicon R.Butté, R.Meaudre, M.Meaudre, S.Vignoli, C.Longeaud, J.P.Kleider, P.Roca i Cabarrocas: Philosophical Magazine B, 1999, 79[7], 1079-95