Correlation between location of light emission and spatial Nitrogen distribution in GaP LED's

Green-light-emitting diodes containing nitrogen only on the n side, the p side, and on both sides have been prepared by a single-step dissolution-regrowth liquid-phase epitaxial process with precisely controlled doping via the vapor phase. Because the ratios of total light emissions of the three diode types were 4:1:5, it is concluded that 80 percent of the light emission from diodes containing nitrogen on both sides is generated on the n side. This observation agrees with measurements of the lateral light output with high spatial resolution. A simple model for light generation in LED's is proposed which can be quantitatively analyzed using the measurements on our diodes and doping dependent material parameters from the literature. According to this model, the optimum doping levels are
n = 10^{17}
cm
^-3
and
p = 10^{18}
cm
^-3
, in agreement with empirical optimizations by other authors.