Extrinsic Polarons: Engineering Coexistence Between Free and Trapped Carriers

The coexistence of high and low conductance states in semiconducting material systems is of great interest, to both the scientific and technological research communities, due to its enormous utility within computing applications. In this talk, we present an innovative approach for designing extrinsic polaron systems in which the coexistence between delocalized and localized states may be tuned through extrinsic polaron dopants. As a model system to explore these physics we have selected Ti-doped SnO2. Through comprehensive first-principles calculations, we demonstrate how strain and alloying can be employed to engineer the coexistence properties within this archetypal extrinsic polaron system. Moreover, we are able to further crystalize these first-principles findings through a compact tight-binding model. Our results indicate that lattice strain and alloying concentration are the two primary means by which the activation barrier between localized and delocalized states can be tuned in extrinsic polaron materials. Overall, this study presents an exciting route toward engineering carrier localization within computing applications and probing its behavior in strongly correlated materials.