Electroluminescence of Diffused GaAs1 − xPx Diodes with Low Donor Concentrations

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Abstract
The optical and electrical properties of electroluminescent diodes formed by Zn diffusion into vapor epitaxially grown substrates with donor concentrations in the range 1016–1017 cm−3 have been studied. This doping range, which is somewhat lower than has been previously investigated in the GaAs1−xPx alloy system, has been found to be the optimum range for the fabrication of high efficiency diodes. The spectral emission is appreciably different than has been previously observed. Throughout the alloy composition range at 300° and 77°K a high energy peak occurs within ∼20 meV of the conduction bandedge, and at 77°K a second peak ∼30 meV lower in energy is present. Donor‐acceptor‐pair recombination peaks similar to those observed in GaP, located ∼0.1 and ∼0.37 eV below the bandedge, are found to occur and remain the same distance below the bandedge throughout the indirect region of alloy composition. At 300°K direct recombination from the higher lying k = 0 minimum is observed to persist into the indirect gap alloy composition region. Diode fabrication techniques were found to have a strong effect on the shape of the spectral emission curves.