Metal-insulator transition in a semiconductor nanocrystal network

Benjamin L. Greenberg, Zachary L. Robinson, Yilikal Ayino, Jacob T. Held, Timothy A. Peterson, K. Andre Mkhoyan, Vlad S. Pribiag, Eray S. Aydil, Uwe R. Kortshagen

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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, σ, in the 0 K limit has been elusive. Here, we examine the temperature dependence of σ of ZnO NC networks. Attaining both higher σ 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 σ ∝ 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, ρ.

Original languageEnglish (US)
Article numbereaaw1462
JournalScience Advances
Issue number8
StatePublished - Aug 23 2019

ASJC Scopus subject areas

  • General


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