Degradation of GaAs lasers and light-emitting diodes on silicon substrates

Abstract

The degradation of single-quantum-well graded-refractive-index GaAs lasers and light-emitting diodes grown on silicon substrates by metallo-organic vapor deposition is studied. The mechanism resulting in degradation appears to be identical with that observed in GaAs devices on GaAs substrates. However, the devices degrade very rapidly, even under pulsed operation, owing to the presence of a very high density of non-radiative regions which results from the dislocations caused by the 4.1% lattice mismatch between the GaAs and the silicon substrate. Continuous operation has been obtained up to 160 K. At higher temperatures the dark regions quench the emission 3–5 μs after the start of a current pulse. This prevents the continuous operation at room temperature of these lasers. During operation the dark regions grow rapidly in size by non-radiative electron-hole recombination in the presence of the large tensile stress in the epilayer. We estimate that it will be necessary to reduce the defect density to less than about 10 4 cm −2 and to prevent the growth of defects in the active layer in order to achieve reliable operation of light-emitting devices.