Resolving alternating stress gradients and dislocation densities across AlxGa1-xN multilayer structures on Si(111)

Research output: Contribution to journalArticleResearchpeer-review

Authors

External Organisational units

  • Infineon Technologies AG Austria
  • Materials Center Leoben Forschungs GmbH
  • KAI - Kompetenzzentrum Automobil- und Industrieelektronik GmbH

Abstract

Gradients of residual stresses and crystal qualities across a 2 μm thick AlN/Al0.32Ga0.68N/GaN/Al0.17Ga0.83N multilayer stack deposited on Si (111) were evaluated by combining the following techniques: High-resolution X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), high resolution transmission electron microscopy, and ion beam layer removal method (ILR) with 100 nm depth resolution. ILR reveals the alternating stress profiles, which are related to sublayer dislocation-density gradients. The laboratory XRD confirms the derived mean stress values, the presence of stress gradients within the sublayers, and decreasing average sublayer threading dislocation-densities across the heterostructure. Additionally, the decreasing dislocation-densities within the individual sublayers are visualized by STEM. The documented stepwise improved crystal quality enables the formation of a highly tensile stressed 20 nm thick Al0.17Ga0.83N top barrier layer, resulting in a pseudomorphic GaN/Al0.17Ga0.83N interface.

Details

Original languageEnglish
Pages (from-to)162103
Number of pages4
JournalApplied physics letters
Volume111.2017
Issue number16
DOIs
Publication statusE-pub ahead of print - 16 Oct 2017