Visible light-emitting diodes grown on optimized ∇x[InxGa1−x]P/GaP epitaxial transparent substrates with controlled dislocation density

Epitaxial transparent-substrate light-emitting diodes (ETS-LEDs) have been fabricated on optimized graded buffers of InxGa1−xP on GaP (∇x[InxGa1−x]P/GaP) that feature controlled threading dislocation densities of 3×106 cm−2. The ETSLEDs show increasing efficiency from 575 nm to 655 nm, in marked contrast to previous reports where performance drops above 600 nm, and feature the lowest spectral widths ever reported in ∇x[InxGa1−x]P/GaP. The improvement over earlier reports is attributed to large mean dislocation spacings in optimized ∇x[InxGa1−x]P/GaP, which are an order of magnitude greater than the mean carrier diffusion length. A slight performance decline remains at 655 nm, but the overall performance of this first generation of ETS-LEDs is promising.