The microstructure of non-polar a-plane (11 2 0) InGaN quantum wells

Atom probe tomography and quantitative scanning transmission electron microscopy are used to assess the composition of non-polar a-plane (11-20) InGaN quantum wells for applications in optoelectronics. The average quantum well composition measured by atom probe tomography and quantitative scanning transmission electron microscopy quantitatively agrees with measurements by X-ray diffraction. Atom probe tomography is further applied to study the distribution of indium atoms in non-polar a-plane (11-20) InGaN quantum wells. An inhomogeneous indium distribution is observed by frequency distribution analysis of the atom probe tomography measurements. The optical properties of non-polar (11-20) InGaN quantum wells with indium compositions varying from 7.9% to 20.6% are studied. In contrast to non-polar m-plane (1-100) InGaN quantum wells, the non-polar a-plane (11-20) InGaN quantum wells emit at longer emission wavelengths at the equivalent indium composition. The non-polar a-plane (11-20) quantum wells also show broader spectral linewidths. The longer emission wavelengths and broader spectral linewidths may be related to the observed inhomogeneous indium distribution.This work was carried out with the support of the United Kingdom Engineering and Physical Sciences Research Council under Grants Nos. EP\J001627\1, EP/I012591/1, and EP\J003603\1. The European Research Council has also provided financial support under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement No. 279361 (MACONS). J. Etheridge and S. D. Findlay acknowledge funding from the Australian Research Council (ARC) (Project Nos. DP110104734 and DP110101570, respectively). The Titan3 80-300 TEM/STEM at the Monash Centre for Electron Microscopy was supported by the ARC Grant No. LE0454166.This is the final version of the article. It first appeared from the American Institute of Physics via http://dx.doi.org/10.1063/1.494829