Nanoscale cathodoluminescene imaging of III-nitride-based LEDs with semipolar quantum wells in a scanning transmission electron microscope

摘要

The optical and crystalline properties of a c-plane GaN-based LED structure with embedded semipolar InGaN quantum wells (QW) were investigated using highly spatially resolved cathodoluminescence spectroscopy (CL) directly performed in a scanning transmission electron microscope (STEM). Direct correlation of the cross-sectional STEM image with the simultaneously recorded spatially resolved CL mapping at room-temperature reveals the most intense emission coming from the semipolar InGaN QWs. We observe an inhomogeneous wavelength distribution due to local indium fluctuations and varyingQW thickness. In contrast, the donor-acceptor pair recombination (DAP) becomes the dominating luminescence process at 16K resulting in a superposition of the DAP luminescence and the InGaN QW emission. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim