Development of 1.0- to 1.4-Micrometer Heterojunction LEDs.

Abstract : Both VPE and LPE InGaAsP/InP edge- and surface-emitting LEDs have been fabricated and tested under the present contract. Table 1 contains a summary of the results. Although the surface emitter provides greater total power, its halfwidth is considerably larger than that of the edge emitter. This increases pulse dispersion and reduces the amount of power that can be coupled into an optical fiber. The experimental conditions for the vapor-phase growth of InGaAsP and InP alloy are described. Detailed growth procedures are specified and plots of alloy composition, bandgap, lattice parameter and doping levels vs growth parameters are included. Modulation rates close to 100 MHz have been measured for 1.27-micron edge-emitting LEDs. Fall times on the order of 10 ns for (90 to 10% response) also have been obtained. Over fifty edge-emitting VPE 1.27-micron heterojunction LEDs have been fabricated from numerous wafers. External power efficiencies equal to or greater than 0.3% were routinely measured, with maximum efficiencies on the order of 0.7% (from one edge). Wafer-to-wafer reproducibility of power efficiencies has now been demonstrated with both the LPE and VPE growth techniques.