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Stress and Microstructure Evolution in Compositionally Graded Al1-xGaxN Buffer Layers for GaN Growth on Si

Published online by Cambridge University Press:  01 February 2011

Xiaojun Weng ,
Srinivasan Raghavan ,
Elizabeth C Dickey  and
Joan M Redwing
Xiaojun Weng
Affiliation:
sxr36@psu.edu, Penn State University, 101 MRI Building, 230 Innovation Blvd, University Park, PA, 16802, United States
Srinivasan Raghavan
Affiliation:
srx36@psu.edu
Elizabeth C Dickey
Affiliation:
ecd10@psu.edu
Joan M Redwing
Affiliation:
jmr31@psu.edu
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Abstract

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.

Keywords

transmission electron microscopy (TEM)dislocationsnitride
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 892 , 2005 , 0892-FF02-02
Copyright
Copyright © Materials Research Society 2006

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References

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