Variable-range-hopping conduction processes in oxygen deficient polycrystalline ZnO films

Yung Lung Huang*, Shao Pin Chiu, Zhi Xin Zhu, Zhi Qing Li, Juhn-Jong Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


We have fabricated oxygen deficient polycrystalline ZnO films by the rf sputtering deposition method. To systematically investigate the charge transport mechanisms in these samples, the electrical resistivities have been measured over a wide range of temperature from 300 K down to liquid-helium temperatures. We found that below about 100 K, the variable-range-hopping (VRH) conduction processes govern the charge transport properties. In particular, the Mott VRH conduction process dominates at higher temperatures, while crossing over to the Efros-Shklovskii (ES) VRH conduction process at lower temperatures. The crossover occurred at temperatures as high as a few tens degrees kelvin. Moreover, the temperature behavior of resistivity over the entire VRH conduction regime from the Mott-type to the ES-type process can be well described by a universal scaling law.

Original languageEnglish
Article number063715
Number of pages6
JournalJournal of Applied Physics
Issue number6
StatePublished - 14 Apr 2010

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