Structural, electrical, and optical properties of hydrogen-doped ZnO films

Achim Kronenberger, Angelika Polity, Detlev M. Hofmann, Bruno K. Meyer, André Schleife, Friedhelm Bechstedt

Research output: Contribution to journalArticle

Abstract

Hydrogen doped ZnO thin films were deposited by radio frequency magnetron sputtering from a ceramic target on c-plane sapphire and fused silica using H 2 and O 2 as reactive gases. Structural analysis revealed that all films are polycrystalline with the c axis oriented perpendicularly to the substrate surface. The lateral grain size was strongly affected by the oxygen content of the sputtering gas and decreased dramatically above a critical content of 4.5%. We were able to adjust the carrier density of the films by the deposition parameters to any value between 1014 and 2×1020 cm -3. Using temperature-dependent Hall-effect measurements we identified thermionic emission over Coulomb-barriers created by surface trap states at the grain boundaries and tunneling effects to dominate the carrier transport. Preparing and thoroughly characterizing the films is a prerequisite for our investigation of the dependence of the optical band gap energy on the carrier density. We use results from experiment as well as first-principles calculations (including Burstein-Moss shift, band gap renormalization, and excitonic effects) in order to understand the mechanisms that determine how free electrons influence the energy position of the optical absorption onset.

Original languageEnglish (US)
Article number115334
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number11
DOIs
StatePublished - Sep 28 2012
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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