High-Performance $\hbox{In}_{0.5}\hbox{Ga}_{0.5} \hbox{As/GaAs}$ Quantum-Dot Lasers on Silicon With Multiple-Layer Quantum-Dot Dislocation Filters

Abstract

Compound-semiconductor-based lasers grown directly on silicon substrates would constitute an important technology for the realization of on-chip optical interconnects. The characteristics of GaAs-or InP-based devices on silicon can be degraded by the large density of propagating dislocations resulting from the large lattice mismatch (> 4%). The use of multiple layers of self-organized In(Ga, Al)As/GaAs quantum dots (QDs) as a 3D dislocation filter to impede the propagation of dislocations and to reduce dislocation density in GaAs/Si lattice-mismatched heterostructures has been investigated. The effectiveness of this technique, depending on QD composition, size, areal density, and number of dot layers, is analyzed by a quasi-3D model of strain-dislocation interaction. It is found that ten layers of InAs QDs of size ~20-30 nm constitute the most effective dislocation filter. This is experimentally verified by cross-sectional transmission electron microscopy, photoluminescence, and performance characteristics of In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> As/GaAs QD separate confinement heterostructure lasers on Si. The lasers exhibit J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ~900 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 273 K, the large characteristic temperature (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> =278 K) is in the temperature range of 5degC-85degC, and the output slope efficiency (~0.4 W/A) is independent of temperature in the range of 5degC-50degC.