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

Abstract

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 InGaAsP/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.

Photoreflectance investigations of quantum well intermixing processes in compressively strained InGaAsP∕InGaAsP quantum well laser structures emitting at 1.55μm

“…33,50 The remaining material parameters have been taken as constant and well known values. V strain e,h ͑z͒, involves biaxial and shear components of strain and was calculated according to Ref.…”

“…However, most of the studies concerning the intermixing behavior have been performed for GaAs/ AlGaAs QW's 5,9,[12][13][14][15][16][17][18][19] and little work has been done on the intermixing behavior of InP based QW structures. [27][28][29][30][31][32][33][34][35] Most of the interdiffusion coefficients have been investigated by photoluminescence ͑PL͒, 36,37 x-ray diffraction ͑XRD͒, Raman spectroscopy ͑RS͒, 38 secondary ion mass spectroscopy ͑SIMS͒, 5,39 transmission electron microscopy ͑TEM͒, and cross-sectional scanning tunneling microscopy ͑STM͒. Only a few reports have been published on the optical properties compressively strained InGaAsP / InGaAsP QWI in the presence of a built-in electric field.…”