Probing the indium clustering in InGaAs∕GaAs quantum wells by room temperature contactless electroreflectance and photoluminescence spectroscopy

Room temperature contactless electroreflectance (CER) supported by photoluminescence (PL) has been proposed as a fast and nondestructive ex situ technique for testing the effect of atom clustering in quantum wells (QWs). The indium clustering in InGaAs∕GaAs QWs was achieved by increasing the growth temperature. It has been shown that this effect causes significant changes in the spectral response. While the line shape of the GaAs-related CER feature remains unaffected there appear broad resonances similar to those for naturally inhomogeneous ensemble of self-assembled quantum dots instead of sharp and intensive lines characteristic for QWs. Additionally, the PL signal exhibits a quantum-dot-like behavior as well, i.e., strongly broadened Gaussian-like peaks with linear excitation power dependence on their intensity and the occurrence of the state filling effect for high excitation.