Electroluminescent shockley diodes of GaAs and GaAsl−x,Px

GaAs and GaAs_1−xP_x p-n-p-n Shockley diode structures have teen prepared by an epitaxial vapor-phase growth technique. The two-terminal devices exhibit a negative-resistance I-V characteristic, which allows them to be used as an electroluminescent diode with a built-in latching capability. The GaAs diodes have breakover voltages between 2 and 30 V at room temperature, and switching characteristics which depend appreciably on the impurity concentrations and thicknesses of the two inner layers. After breakdown, the diodes emit near-bandgap infrared radiation with external quantum efficiencies as high as 0.39%. The emission spectra have been found to consist of two peaks, one corresponding to recombination in the innermost n-layer, and the other corresponding to recombination in one of the two p-type layers. The emission for the GaAs diodes occurs uniformly over the entire surface area. For GaAs_1−x P_x, the type of compositional grading used between the GaAs substrate and the p-n junction regions has been found to dramatically affect the I-V characteristics and switching capabilities of the Shockley diodes. Most importantly, the emission from the GaAs_1−xP_x devices occurs in small filaments for alloys with x ≃ 0.18. At high currents, the filaments form an orthogonal grid pattern parallel to {110} planes, thereby demonstrating a clear relationship to lattice-misfit dislocations generated during compositional grading. This research was supported in part by the Office of Naval Research, Arlington, Va., and in part by RCA Laboratories, Princeton, New Jersey.