Abstract
A new simple‐geometry (sawed rectangular parallelopiped) Ga1−xAlxAs LED having external quantum efficiency as high as 27% has been developed. The material is prepared by a single‐step multiple‐slice liquid‐phase‐epitaxy technique and contains a steep Al composition gradient. This gradient is exploited by removing the GaAs substrate and extracting photons from the first‐to‐grow side of the epitaxial material along a path of very low absorption. The spectral distribution of these LED’s can be varied over a broad range. Accelerated aging studies indicate very high reliability for these devices.