Low temperature Photoreflectance analysis of movpe GaAs/AlGaAs Multiple Quantum Wells on (111)A GaAs substrates

A combination of High-Resolution X-Ray Diffractometry (HRXRD), low temperature Photoreflectance (PR) and Photoluminescence techniques has been applied to evaluate the interfaces of a 25-period GaAs/Al0.27Ga0.73As Multi-Quantum-Well (MQW) structure grown on a (111)A GaAs substrate by atmospheric pressure metalorganic vapor phase epitaxy. The structural parameters of the MQW were accurately determined by HRXRD. The PR spectrum shows all the possible optical transitions between confined hole and electron subbands. From a detailed Monolayer (ML) analysis it is shown that the Quantum Wells (QWs) have interfaces with abruptness on the order of 1 ML. Photoluminescence (PL) measurements were also used to independently assess the QW interfaces and the period repeatability. The PL Full Width at Half Maximum (FWHM) is 12.5 meV, which also corresponds to less than a +/-1 ML well width fluctuation throughout the 25-period MQW. This FWHM is the best value reported to date for a GaAs/AlGaAs MQW structure grown on (111)A or B GaAs substrates by any growth technique.