Event Details

First In-Person Physics & Astronomy Seminar Lecture since 2019!"Unexpected Transport Phenomena in Composite Amorphous/Nanochrystalline Thin Films"
James Kakalios, Professor, School of Physics & Astronomy, University of Minnesota is presenting.
Composite materials consisting of nanocrystalline semiconductors embedded within a bulk amorphous semiconductor combine the best of both worlds – the thin film large area advantages of disordered semiconductors with the superior opto-electronic properties of crystals, and often display electronic properties not observed in either material separately. Despite 40 years of study – basic questions remain regarding the nature of charge transport in strongly disordered semiconductors. We have found that conduction above room temperature in composite and amorphous semiconductors is best described by anomalous hopping expression σ = σ1 exp[-(To/T)3/4]in contrast to the standard Mott Mobility Gap model which predicts a simple Arrhenius temperature dependence. This conductivity temperature dependence MAY reflect filamentary conduction – though a full theoretical understanding is lacking.Snacks at 3 PM.