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Strain and Compositional Analysis of InGaN/GaN Layers

Published online by Cambridge University Press:  17 March 2011

Sérgio Pereira ,
Maria. R. Correia ,
Estela Pereira ,
C. Trager-Cowan ,
F. Sweeney ,
P.R. Edwards ,
K.P. O'Donnell ,
E. Alves ,
A.D. Sequeira  and
N. Franco
Sérgio Pereira
Affiliation:
Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 0NG, UK
Maria. R. Correia
Affiliation:
Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal
Estela Pereira
Affiliation:
Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro, Portugal
C. Trager-Cowan
Affiliation:
Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 0NG, UK
F. Sweeney
Affiliation:
Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 0NG, UK
P.R. Edwards
Affiliation:
Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 0NG, UK
K.P. O'Donnell
Affiliation:
Department of Physics and Applied Physics, University of Strathclyde, Glasgow G4 0NG, UK
E. Alves
Affiliation:
I.T.N., Departamento de Física, E.N.10, 2686-935 Sacavém, Portugal
A.D. Sequeira
Affiliation:
I.T.N., Departamento de Física, E.N.10, 2686-935 Sacavém, Portugal
N. Franco
Affiliation:
I.T.N., Departamento de Física, E.N.10, 2686-935 Sacavém, Portugal
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Abstract

We investigate strain and composition of epitaxial single layers of wurtzite InxGa1−xN (0<x<0.25) grown by MOCVD on top of GaN/Al203 substrates. It is shown that significant inaccuracies may arise in composition assessments if strain in InxGa1−xN/GaN heterostructures is not properly taken into account. Rutherford backscattering spectrometry (RBS) measures composition, free from the effects of strain and with depth resolution. Using X-ray diffraction (XRD) we measure both a- and c- parameters of the strained wurtzite films. By measuring both lattice parameters and solving Hooke's equation, a good estimation for composition can be obtained from XRD data. The agreement between RBS and XRD data for composition allows reliable values for perpendicular (εzz) and parallel strain components ( (εxx) to be determined. RBS and depth resolved cathodoluminescence (CL) measurements further indicate that the indium content is not uniform over depth in some samples. This effect occurs for the most strained layers, suggesting that strain is the driving force for compositional pulling.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 639: Symposium G – GaN and Related Alloys-2000 , 2000 , G3.52
Copyright
Copyright © Materials Research Society 2001

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References

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