GaP RED ELECTROLUMINESCENT DIODES WITH AN EXTERNAL QUANTUM EFFICIENCY OF 7%

Abstract

External quantum efficiencies η as high as 7.2% have been obtained for gallium phosphide red light emitting diodes. The p-n junctions were prepared using a p-on-n liquid phase epitaxy process in which the dopant levels significantly differ from those previously reported. Doping profiles for these junctions are compared with earlier n-on-p structures (η = 1–2%) and it is suggested that the observed high efficiencies result from (1) more efficient electron injection, (2) increased O concentration in the p-type layers which may result in a higher concentration of Zn–O complexes, and/or (3) fewer free holes in the p region contributing to nonradiative recombination.