Controlling the interface charge density in GaN-based metal-oxide-semiconductor heterostructures by plasma oxidation of metal layers

Herwig Hahn, B. Pécz, András Kovács, Michael Heuken, Holger Kalisch, Andrei Vescan

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In recent years, investigating and engineering the oxide-semiconductor interface in GaN-based devices has come into focus. This has been driven by a large effort to increase the gate robustness and to obtain enhancement mode transistors. Since it has been shown that deep interface states act as fixed interface charge in the typical transistor operating regime, it appears desirable to intentionally incorporate negative interface charge, and thus, to allow for a positive shift in threshold voltage of transistors to realise enhancement mode behaviour. A rather new approach to obtain such negative charge is the plasma-oxidation of thin metal layers. In this study, we present transmission electron microscopy and energy dispersive X-ray spectroscopy analysis as well as electrical data for Al-, Ti-, and Zr-based thin oxide films on a GaN-based heterostructure. It is shown that the plasma-oxidised layers have a polycrystalline morphology. An interfacial amorphous oxide layer is only detectable in the case of Zr. In addition, all films exhibit net negative charge with varying densities. The Zr layer is providing a negative interface charge density of more than 1 × 1013cm-2 allowing to considerably shift the threshold voltage to more positive values.

Original languageEnglish
Article number214503
JournalJournal of Applied Physics
Volume117
Issue number21
DOIs
Publication statusPublished - Jun 7 2015

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metal oxide semiconductors
oxidation
transistors
metals
threshold voltage
plasma layers
oxides
augmentation
shift
oxide films
engineering
electron energy
transmission electron microscopy
spectroscopy
x rays

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Controlling the interface charge density in GaN-based metal-oxide-semiconductor heterostructures by plasma oxidation of metal layers. / Hahn, Herwig; Pécz, B.; Kovács, András; Heuken, Michael; Kalisch, Holger; Vescan, Andrei.

In: Journal of Applied Physics, Vol. 117, No. 21, 214503, 07.06.2015.

Research output: Contribution to journalArticle

Hahn, Herwig ; Pécz, B. ; Kovács, András ; Heuken, Michael ; Kalisch, Holger ; Vescan, Andrei. / Controlling the interface charge density in GaN-based metal-oxide-semiconductor heterostructures by plasma oxidation of metal layers. In: Journal of Applied Physics. 2015 ; Vol. 117, No. 21.
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