A nominal well width (20 nm) of Al0.08Ga0.92As quantum well structure has been fabricated by molecular beam epitaxy technique with the aim of obtaining a lasing device. The temperature evolution of quantum well photoluminescence was studied in the range 10-300 K which shows excitons being trapped at the interfacial defects below 100 K. The linear polarization effects in the photoluminescence have been studied for the incident and collected light propagating parallel to the plane of the well layer. In a very careful study, the luminescence was found to be fully polarized for the incident electric vector parallel to well layers, while it showed depolarized behaviour for the incident electric vector perpendicular to the well layers. The earlier conclusions based on photoluminescence excitation and absorption studies of heavy- and light-hole emissions are supported. The 20 nm quantum well structure has been corroborated using scanning tunnelling microscopy.