Engineering high-quality InxGa1-xP graded composition buffers on GaP for transparent substrate light-emitting diodes

We present the development of high-quality InxGa1-xP graded buffers on GaP substrates (InxGa1-xP/GaP) for use in epitaxial transparent-substrate light-emitting diodes. The evolution of microstructure and dislocation dynamics of these materials has been explored as a function of growth conditions. The primarily limiting factor in obtaining high-quality InxGa1-xP/GaP is a new defect microstructure that we call branch defects. Branch defects pin dislocations and result in dislocation pileups that cause an escalation in threading dislocation density with continued grading.