Significant mobility enhancement in extremely thin highly doped ZnO films

David C. Look, Eric R. Heller, Yu Feng Yao, C. C. Yang

Research output: Contribution to journalArticlepeer-review

Abstract

Highly Ga-doped ZnO (GZO) films of thicknesses d = 5, 25, 50, and 300 nm, grown on 160-nm ZnO buffer layers by molecular beam epitaxy, had 294-K Hall-effect mobilities μH of 64.1, 43.4, 37.0, and 34.2 cm2/V-s, respectively. This extremely unusual ordering of μH vs d is explained by the existence of a very high-mobility Debye tail in the ZnO, arising from the large Fermi-level mismatch between the GZO and the ZnO. Scattering theory in conjunction with Poisson analysis predicts a Debye-tail mobility of 206 cm2/V-s at the interface (z = d), falling to 58 cm2/V-s at z = d + 2 nm. Excellent fits to μH vs d and sheet concentration ns vs d are obtained with no adjustable parameters.
Original languageEnglish
Article number152102
JournalApplied Physics Letters
Volume106
Issue number15
DOIs
StatePublished - Apr 13 2015

ASJC Scopus Subject Areas

  • Physics and Astronomy (miscellaneous)

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