Voltage Dependence of Electroluminescence from GaP Diodes Prepared by Liquid Epitaxial Techniques

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Abstract
Investigations are reported on the voltage dependence of red and green electroluminescence in GaP diodes prepared by the growth of an n‐type liquid‐epitaxial layer on a p‐type solution‐grown substrate. The green‐emission intensity is found to be proportional to exp (eV/kT) for all the devices studied. The voltage dependence of the red‐emission intensity for devices exhibiting a predominantly red visual appearance is found amenable to interpretation using the theoretical model proposed by Morgan, or that of Nelson. The anomalous behavior of the red‐emission intensity in diodes with a predominantly green visual appearance permitted classification of the devices into three groups. The first group contained devices whose red intensity voltage dependence followed Nelson's theory. The dependence of the diodes in the second could be interpreted using Nelson's theory with some modifications. The third group of diodes possessed a red‐intensity voltage dependence which was not amenable to interpretation in terms of available theoretical models. The green peak in diodes with a predominantly green visual appearance is attributed to the so‐called ``A'' line resulting from excitonic transitions via impurity levels introduced by the isoelectronic substitution of nitrogen atoms on phosphorus sites.