Detailed analysis of Ga-rich current pathways created in an n-Al0.7Ga0.3N layer grown on an AlN template with dense macrosteps

Abstract

To clarify the behavior of the AlGaN composition in 20-nm-wide Ga-rich current pathways in an n-AlGaN layer, which assist carrier localization in our AlGaN-based LEDs, a detailed analysis was performed using an n-Al_0.7Ga_0.3N layer on AlN having dense macrosteps on a 1.0°-miscut sapphire substrate. Energy-dispersive X-ray (EDX) spectra obtained using cross-sectional scanning transmission electron microscopy (STEM) calibrated by Rutherford backscattering (RBS) and cross-sectional cathodoluminescence (CL) spectra indicated that the AlGaN composition in Ga-rich current pathways was nearly ~2/3. The result is consistent with those of other research groups, suggesting that metastable Al_2/3Ga_1/3N is created in Ga-rich current pathways.