Mike no news on chips but this e-mail from Donald Shorling looks interesting .
Light Induced Intensity Change of Rayleigh Scattering in a-Si:H
David Tsu, Stanford R. Ovshinsky (Energy Conversion Devices, Inc. Troy, MI 48084), Raphael Tsu (University of North Carolina at Charlotte, Charlotte NC 28223)
Very large change in the intensity of Rayleigh scattering (RS) from a-Si:H due to light soaking (LS) is presented. For the usual high performance PV quality a-Si:H samples, RS intensity is 25 times higher after LS under 30 suns at 50 C for 40 minutes. However, for samples with high hydrogen dilution, RS intensity is 3 times higher than without H-dilution, and is 2.5 times lower after LS. Furthermore, for the usual samples, annealing at 180 C for 45 hrs. can nearly restore the pre-LS values, but annealing has no effect on samples with high H-dilution. Since RS intensity mainly depends on two terms: change of dielectric function of the microstructure, and change of the effective size of the clusters, our results suggest that: clusters must exist and (2) the effective size of the clusters may be increased or decreased by light soaking. Recalling that LS can change SANS (small angle neutron scattering) by 25%, a factor of 25 or more in the intensity change in RS indicates that Rayleigh scattering can provide sensitive probing of changes in the nature of heterogeneity in a-Si:H. |
