Role of gross well-width fluctuations in bright, green-emitting single InGaN∕GaN quantum well structures

Gross well-width fluctuations have been observed by transmission electron microscopy (TEM) in single InGaN∕GaN quantum wells (QWs) grown by metal-organic vapor phase epitaxy. Similar thickness variations are observed in commercial, green InGaN∕GaN multi-QW light emitting diodes. Atomic force microscopy studies of equivalent epilayers suggest that these fluctuations arise from a network of interlinking InGaN strips, which are found (using TEM) to be indium rich at their centers. Plan-view TEM indicates that 90±8% of all threading dislocations (TDs) intersect the QW plane between the InGaN strips. Excitons may be localized at the strips’ centers, preventing nonradiative recombination at TDs.