Stress and microstructure evolution in compositionally graded Al 1-xGaxN buffer layers for GaN growth on Si

Xiaojun Weng, Srinivasan Raghavan, Elizabeth C. Dickey, Joan Marie Redwing

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


We have studied the evolution of stress and microstructure of compositionally graded Al1-xGaxN (0 ≤ x ≤ 1) buffer layers on (111) Si substrates with varying thicknesses. In-situ stress measurements reveal a tensile-to-compressive stress transition that occurs near the half-thickness in each buffer layer. Cross-sectional transmission electron microscopy (TEM) shows a significant reduction in threading dislocation (TD) density in the top half of the buffer layer, suggesting that the compressive stress enhances the threading dislocation annihilation. The composition of the buffer layers varies linearly with thickness, as determined by X-ray energy dispersive spectrometry (XEDS). The composition grading-induced compressive stress offsets the tensile stress introduced by microstructure evolution, thus yielding a tensile-to-compressive stress transition at x ≈ 0.5.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium Proceedings
Number of pages6
StatePublished - May 15 2006
Event2005 Materials Research Society Fall Meeting - Boston, MA, United States
Duration: Nov 28 2005Dec 1 2005

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


Other2005 Materials Research Society Fall Meeting
Country/TerritoryUnited States
CityBoston, MA

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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