The Koster‐Slater one‐band one‐site model has been employed to investigate the modulus of the wave function of an electron bound to a N isoelectronic trap in GaAs1−xPx:N as a function of crystal compositionx. The no‐phonon recombination transition involving the trapped electron is enhanced as the crystal composition is changed to bring the &Ggr; conduction band minimum,E&Ggr;, near the N‐trap level,EN. Absorption data taken onx= 1.0 andx= 0.53 GaAs1−xPx:N are consistent with the calculated increase in the probability density in the &Ggr; region asE&Ggr;decreases relative toEX. The change in the internal quantum efficiency as a function of crystal composition has been calculated assuming that the nonradiative component of recombination is independent ofx. By weighting the internal recombination‐radiation quantum efficiency by the photopic response of the eye, we have determined that the optimum range of crystal compositions in which to fabricate GaAs1−xPx:N LED's is 0.6 ≤x≤ 0.8. This result is in good agreement with current GaAs1−xPx:N LED fabrication processes.