Study of the exciton transitions in InGaAsP/InGaAsP MQWs to determine the band offset of the structure

摘要

A detailed analysis of the excitonic transitions of 8 InGaAsP MQWs grown by MOCVD into a InGaAsP barriers with different composition has permitted to experimentally determine the band offset for In-GaAsP/InGaAsP heterostructures. We find a value of about 44% referred to the valence band, which is lower than the value reported for unstrained structure (≈ 56%) and in good agreement with the value estimated by a theoretical model specifically developed to design the structure. Additionally, we compared the values of the activation energies, obtained from the fits to exciton transition PL intensity, with the carrier confinement energy evaluated theoretically. The obtained activation energies confirms that in such heterostructures the unipolar detrapping of carriers is more efficient than the exciton escape.