Growth and properties of AlGaInP resonant cavity light emitting diodes on Ge∕SiGe∕Si substrates

Abstract

Visible AlGaInP resonant cavity light emitting diodes (RCLEDs) were grown by molecular beam epitaxy and fabricated on low-dislocation density, SiGe∕Si metamorphic substrates. A comparison with identical devices grown on GaAs and Ge substrates shows that not only did the RCLED device structure successfully transfer to the SiGe∕Si substrate, but also a higher optical output power was obtained. This result is attributed to enhanced lateral current spreading by the low residual dislocation density (∼1×106cm−2) network within the virtual Ge substrate and the superior thermal conductivity of the underlying Si wafer. In addition, the growth of an AlGaAs current spreading layer and a modified top metal contact were incorporated in the RCLED on SiGe to optimize device performance. The measured electroluminescent output power was 166μW at a 665nm peak wavelength under 500mA current injection. Extremely narrow electroluminescence linewidths were achieved with a full width half maximum value of 3.63nm under 50mA current injection. These results demonstrate great promise for the monolithic integration of visible band optical sources with Si-based electronic circuitry.