Infrared p-n-junction diodes in epitaxial narrow gap PbTe layers on Si substrates

The characteristics of p-n+ junctions in PbTe layers on Si(111) grown by molecular beam epitaxy are described. The temperature dependence of the leakage currents and ideality factors show that the junctions are generation-recombination limited over the 300–100 K range. The lifetimes deduced for the minority carriers (about 0.1 ns) suggest that their diffusion length is limited by the density of the threading dislocations, which was about 108 cm−2 for these heavily lattice mismatched layers. The theoretical diffusion limit at 200 K would be attained by reducing the dislocation density by a factor of 100. Such low densities have already been obtained in lead–chalcogenide layers on Si substrates by temperature cyclings.