Improved AlScN/GaN heterostructures grown by metal-organic chemical vapor deposition

Christian Manz, Stefano Leone (Corresponding author), Lutz Kirste, Jana Ligl, Kathrin Frei, Theodor Fuchs, Mario Prescher, Patrick Waltereit, Marcel A. Verheijen, Andreas Graff, Michél Simon-Najasek, Frank Altmann, Michael Fiederle, Oliver Ambacher

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

AlScN/GaN epitaxial heterostructures have raised much interest in recent years, because of the high potential of such structures for high-frequency and high-power electronic applications. Compared to conventional AlGaN/GaN heterostructures, the high spontaneous and piezoelectric polarization of AlScN can yield to a five-time increase in sheet carrier density of the two-dimensional electron gas formed at the AlScN/GaN heterointerface. Very promising radio-frequency device performance has been shown on samples deposited by molecular beam epitaxy. Recently, AlScN/GaN heterostructures have been demonstrated, which were processed by the more industrial compatible growth method metal-organic chemical vapor deposition (MOCVD). In this work, SiNx passivated MOCVD-grown AlScN/GaN heterostructures with improved structural quality have been developed. Analytical transmission electron microscopy, secondary ion mass spectrometry and high-resolution x-ray diffraction analysis indicate the presence of undefined interfaces between the epitaxial layers and an uneven distribution of Al and Sc in the AlScN layer. However, AlScN-based high-electron-mobility transistors (HEMT) have been fabricated and compared with AlN/GaN HEMTs. The device characteristics of the AlScN-based HEMT are promising, showing a transconductance close to 500 mS mm-1 and a drain current above 1700 mA mm-1.

Original languageEnglish
Article number034003
Number of pages9
JournalSemiconductor Science and Technology
Volume36
Issue number3
DOIs
Publication statusPublished - Mar 2021

Keywords

  • AlScN
  • Aluminum scandium nitride
  • Atom diffusion
  • High electron mobility transistor
  • MOCVD
  • ScAlN

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