A nondamaging electron microscopy approach to map In distribution in InGaN light-emitting diodes

Dark-field inline electron holography and, for comparison, high-resolution transmission electron microscopy are used to investigate the distribution of indium in GaN-based commercial high-efficiency green light-emitting diodes consisting of InGaN multiquantum wells (QWs). Owing to the low electron doses used in inline holography measurements; this technique allows to map the indium distribution without introducing any noticeable electron beam-induced damage which is hardly avoidable in other quantitative transmission electron microscopy methods. Combining the large field of view with a spatial resolution better than 1 nm, we show that the InGaN QWs exhibit random alloy nature without any evidence of nanometer scale gross indium clustering in the whole active region.