Investigations of optical transitions insingle quantum well structures : by photoreflectance spectroscopy

الملخص EN

The photoreflectance (PR) spectroscopy has been used for the investigation of optical transitions in InGaAsN/GaAs single quantum well structures grown on a GaAs substrate for different nitrogen (N) mole fractions at room temperature.

The addition of a small amount of nitrogen to the InGaAs quantum well (QW) reduces the net strain because, the smaller atomic size of nitrogen decreases the band gap due to a large band gap bowing parameter, it also increases the conduction band offset causing strong electron confinement.

The photoreflectance measurements have allowed us to observe not only the fundamental (e1-hh1) optical transition, but also other transitions between excited states in quantum wells (QWs). We have found the relatively high red shift of all optical transitions with increasing nitrogen content.

All the observed optical transitions have been identified on the bases of the results of the envelope function calculation which includes strain effects.

The dependence of the optical transitions on the nitrogen content has been derived and compared with the results obtained in laboratory experiments.