Bimodality in the Electroluminescence Spectra of InGaAs Quantum Well–Dot Nanostructures

The polarization-resolved electroluminescence spectra of waveguide structures based on quantum well–dots are investigated in the temperature range of 60–300 K. It is found that the ground-state emission consists of two peaks with different degrees of TE polarization. The spectral separation of these peaks decreases with a decrease in temperature. The observed bimodality is attributed to the existence of two different types of objects in the active region, namely, quantum well–dots, whose emission is only partially TE polarized, and quantum dots, which emit nearly fully TE polarized light.