Ground state energy trend in single and multilayered coupled InAs/GaAs QDs capped with InGaAs layers: effect of thickness of InGaAs layer and the RTA treatment

摘要

Vertically coupled multilayered InAs/GaAs QDs covered with thin InGaAs strain reducing layer (SRL) is interesting to address today's technological demand. We report low temperature photoluminescence (PL) investigations for such single and multilayered structures grown using MBE, where SRL thickness is varied. Use of SRL layer within structures is observed to be responsible for high activation energies (Eo) indicating the reduction of the electron phonon interaction in QDs. Deviation of experimental data with Varshni's model (E(T)=Eo-αT2/τ+β) suggests that InAs QDs have different properties than the bulk. Extracted theoretical values of Eo are observed to be much higher than that of bulk InAs, while the values of β ≥ 120 K which are close to InGaAs suggests the strong effect of misfit stress and the quantum confinement effects in the structures. Anomalous behavior of ground state (GS) peak linewidth observed especially for annealed multilayer structures indicates probable inter diffusion of In/Ga atoms between QDs and barrier layers. Blue shift of GS peak position with broadened linewidth with loss of intensity in case of samples annealed at 800 °C can be due to strain driven alloy decomposition as a result of adatom interdiffusion. Presence of SRL layer is observed to prevent the formation of the non radiative centers at high temperature annealing, which usually causes sharp decrease in Ea. This indicates the importance of such structures to be used in optoelectronic applications, where the structures are sandwiched between high temperatures grown InGaAs cladding layers.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.