Hopping conduction characterization in amorphous semiconductors and cross-linked metal nanoparticles

In amorphous semiconductors, e.g. a-Si, conduction occurs via charge carrier hopping between localized states. The key figures of merit in characterization, particularly in microbolometer applications, include the temperature dependence of conductivity, summarized by the temperature coefficient of resistance (TCR), and electrical noise, which are controlled in the hopping regime by the hopping conduction parameters. For next-generation bolometer material, cross-linked metal nanoparticles (CLMPs) conduction occurs via electron hopping between adjacent nanoparticles, and the conductivity exhibits Arrhenius temperature-dependent behavior. In these systems, TCR and noise are theorized to be controlled by nanoparticle diameter and separation distance between adjacent nanoparticles, respectively. Diameter and separation distance in CLMPs are independent of each other, with the separation distance being controlled by organic ligands bonded to the nanoparticle surface. This work examines the effect of different organic ligands on electrical conductivity and TCR in CLMPs.