Metal-insulator transition in a semiconductor nanocrystal network.

ABSTRACT: Many envisioned applications of semiconductor nanocrystals (NCs), such as thermoelectric generators and transparent conductors, require metallic (nonactivated) charge transport across an NC network. Although encouraging signs of metallic or near-metallic transport have been reported, a thorough demonstration of nonzero conductivity, ?, in the 0 K limit has been elusive. Here, we examine the temperature dependence of ? of ZnO NC networks. Attaining both higher ? and lower temperature than in previous studies of ZnO NCs (T as low as 50 mK), we observe a clear transition from the variable-range hopping regime to the metallic regime. The critical point of the transition is distinctly marked by an unusual power law close to ? ? T ^1/5. We analyze the critical conductivity data within a quantum critical scaling framework and estimate the metal-insulator transition (MIT) criterion in terms of the free electron density, n, and interparticle contact radius, ?.

SUBMITTER: Greenberg BL 

PROVIDER: S-EPMC6707780 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature