Suppression of thermal atomic interdiffusion in C-doped InGaAs∕AlGaAs quantum well laser structures using TiO₂ dielectric layers

Abstract

The effects of thermal annealing on C-doped InGaAs∕AlGaAs quantum well laser structures capped with titanium dioxide (TiO₂) layers were investigated. The atomic interdiffusion was greatly suppressed by the presence of a TiO₂ capping layer during annealing, inhibiting even the thermal intermixing observed in the uncapped sample. An increase in the amount of lattice contraction associated with the presence of substitutional carbonCAs after annealing without a capping layer was observed, but not after annealing with a TiO₂ capping layer. Capacitance–voltage measurements confirmed the electrical activation of carbon after annealing without a dielectric layer and show a negligible change after annealing using a TiO₂ capping layer. The possible mechanisms involving both the atomic intermixing on the group III sublattice and carbon activation on the group V sublattice and the implications for optoelectronic device integration using impurity-free intermixing are discussed.