Electron emissions in InAs quantum dots containing a nitrogen incorporation induceddefect state: the influence of thermal annealing

Abstract

With the incorporation of nitrogen (N) into InAs quantum dots (QDs), the carrierdistribution near the QD displays electron emissions from a localized N-induced defectstate at 0.34 eV and a weak emission at 0.15 eV from the QD. This defect state causesdrastic carrier depletion in the neighboring GaAs bottom layer near the QD, which caneffectively suppress tunneling emission for the QD excited states. As a result, electronsescape from the QD ground state through thermal emission to near the GaAsconduction band, rather than through thermal emission to the QD first excited stateand a subsequent tunneling to the GaAs conduction band, as observed in InAsQDs without N incorporation. Thermal annealing can weaken the defect emissionand enhance the QD emission, suggesting a removal of the defect state and arecovery of carriers in the QD. Increasing annealing temperature can significantlydecrease the emission time and energy of the QD emission, which is explainedby a weakening of tunneling suppression due to the removal of the defect state.