Effect of reabsorbed recombination radiation on the saturation current of direct gap p-n junctions

The radiative transfer theory for semiconductors recently developed is applied to p-n junctions under conditions of low level injection. By virtue of the interaction of the radiation field with free carriers across the depletion layer or space charge region, the saturation current density j₀ in Shockley's expression j = j₀[exp (qV/kT) ? 1] for the diode current is reduced at high doping levels from the customary value which neglects radiation effects altogether. While the effect is insignificant in p-type material, it is noticeable in n-type material owing to the small magnitude of the electron effective mass in direct gap III–V compounds. At an equilibrium electron concentration of 2 × 10¹⁸ cm^?3 in GaAs, a reduction of j₀ by 15% is predicted.