Band alignment of zinc oxide as a channel layer in a gate stack structure grown by plasma enhanced atomic layer deposition

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9 Scopus citations

Abstract

A gate stack structure with a thin ZnO layer between an oxidized Si(100) surface and an alloyed hafnium and lanthanum oxide (HfO2-La 2O3) layer was prepared by plasma enhanced atomic layer deposition at ∼175 °C. High resolution electron microscopy indicated an amorphous structure of the deposited layers. The electronic properties were characterized with x-ray and ultraviolet photoemission spectroscopy. A significant amount of excess oxygen was observed in the as-deposited ZnO and (HfO2-La2O3) layers. A helium plasma postdeposition treatment can partially remove the excess oxygen in both layers. The band alignment of this structure was established for an n-type Si substrate. A valence band offset of 1.5 ± 0.1 eV was measured between a thin ZnO layer and a SiO2 layer. The valence band offset between HfO 2-La2O3 (11 HfO2 and 89 La 2O3) and ZnO was almost negligible. The band relationship developed from these results demonstrates confinement of electrons in the ZnO film as a channel layer for thin film transistors.

Original languageEnglish (US)
Article number051807
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Volume30
Issue number5
DOIs
StatePublished - Sep 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

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