An accurate determination of the electronic transitions of InAs/InGaAs/InP quantum dots for midinfrared lasers using simultaneous complementary spectroscopic techniques

Abstract

InAs/InGaAs/InP quantum dots (QDs) emitting at similar to 2 mu m for midinfrared laser applications are studied using the complementary spectroscopic techniques of photoluminescence (PL), photoreflectance (PR), and surface photovoltage spectroscopy (SPS). We use a procedure that ensures that the same sample spot is studied virtually simultaneously by these three different spectroscopic techniques under almost identical conditions. We are able to measure the ground and excited states transitions of the InAs QDs without any ambiguity, thus providing a complete and clear understanding of the electronic transitions. Temperature dependent PL, SPS, and PR measurements provide a systematic thermal evolution of the ground and excited states. However, the QD transitions are not all seen together at any given temperature in either the PL or SPS measurements. By contrast, the PR technique can measure the complete set of ground and two excited state QD transitions and also the InGaAs barrier energy at all studied temperatures.

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