OPTICAL PROPERTIES OF POPULATED InAs/GaAs QUANTUM DOTS

The optical properties of InAs/GaAs Quantum Dots have been studied by comparing the photoreflectance and photoluminescence spectra at different temperatures. The photoreflectance relative spectral intensity between the contributions from InAs wetting layer and the GaAs increases with the decreasing of temperature. The photoluminescence spectral profiles consist of contributions from the equal spacing energy levels of the InAs quantum dots. Since the quantum dot transitions were observed in the photoluminescence spectra and the wetting layer transitions were observed in the photoreflectance spectra, we propose that the Fermi level of the system is located between energy level of the wetting layer and the populated energy level of the quantum dots.