Determination of concentration, strain and internal electric fields in InN and InGaN quantum well and quantum dot structures
|David J. Smith 2, Martha R. McCartney 2, Ted D. Moustakas 3, Papo Chen 3, Tao Xu 3, Lin Zhou 2, Masaki Takeguchi 1|
1. National Institute of Material Science (NIMS), Tsukuba, Japan
The combination of high-resolution electron microscopy (strain field), Z-contrast imaging with the scanning transmission electron microscope (In concentration), convergent-beam electron diffraction (local lattice parameter), and electron holography (internal electric field), represents a powerful approach for studying the effects of compositional differences and local fluctuations in InGaN-related materials. All of these techniques have been used separately or in tandem in our recent studies to investigate phase separation and the effects of local segregation in InGaN quantum dots and quantum well structures. Note that tilting away from exact zone-axes orientations is required for both CBED and EH in order to avoid complications arising from strong elastic and inelastic scattering, but lateral composition changes on the nm-scale can still be measured with +0.5% accuracy using the CBED technique. In compositional fluctuations causing local electric field inhomogeneities seemed to be more pronounced near the onset of InGaN layer growth, suggesting strain relaxation as a strong contributing factor.
Presentation: invited oral at E-MRS Fall Meeting 2005, Symposium A, by David J. Smith
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-07-21 05:16 Revised: 2009-06-07 00:44