An investigation of the properties of new semiconducting alloys and their application to luminescent devices

摘要

Crystals of alloys of GaP with ZnSe have been grown with ZnSe contents up to 8 mol percent. Study of the transport properties of n-type samples of such alloys showed a hopping contribution to the conductivity at low temperatures, and the dominance of ionized impurity scattering above about 150 K. The electron mobility decreased with increasing ZnSe content. The hopping mechanism was found to have an activation energy at low temperatures of about 4 MeV, for all of the alloys studied. Cathodoluminescent studies of the alloys showed no signs of Zn-Se donor-acceptor pair recombination. Diodes fabricated from the alloy material (by the diffusion of Zn as an acceptor impurity) showed electroluminescence at room temperature (and below), although weaker than that found from GaP diodes by as much as two orders of magnitude. For the more heavily alloyed diodes, line spectra were not seen near the band edge; in the reverse bias direction, the emission did tail out to higher energies than seen in the pure GaP diodes. Identifiable pair-recombination emission in the alloy diodes showed a slight decrease in energy with alloying, from 1.95 to 1.91 eV on going to 5% ZnSe.