Vapor Growth of In1 − xGax P for P‐N Junction Electroluminescence: II . Luminescence Characteristics

Abstract

epitaxial layers, prepared by an improved vapor‐phase growth technique, have been evaluated by photoluminescence measurements and by transmission electron microscopy. Maximum photoluminescence intensities for Se‐ and Zn‐doped layers , are observed at carrier concentrations of , respectively. At higher concentrations, a severe degradation in the photoluminescence intensity occurs, concurrent with the appearance (by TEM) of precipitates in concentrations of about 1014 cm−3. For Zn‐doped , the precipitate has been identified as from its electron diffraction pattern. The luminescence spectra from the vapor‐grown layers at 300°K consist of a high‐energy peak, attributed to band‐to‐band recombination, and a low‐energy peak, located 0.4 to 0.5 eV less than bandgap. The low‐energy peak increases with Se donor concentration and with alloy composition, , but is typically orders of magnitude less intense than the bandgap peak. Electroluminescent p‐n junctions prepared with optimum donor and acceptor concentrations have yielded external quantum efficiencies between (unencapsulated) for emission between 6150 and 6600Aå. From such junctions, laser diodes have been fabricated which emit orange coherent radiation between 6105 and 6150Aå with threshold currents as low as 4000 A/cm2 (at 77°K).