The correlation between the formation mechanism and the optical emission of GaAs quantum rings (QRs) is studied for the first time. The GaAs QRs were fabricated by the droplet epitaxy technique on Al0.3Ga0.7As surface using molecular beam epitaxy (MBE). Time evolution of these GaAs QRs with different arsenisation time is presented. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe the structural and geometrical changes during the formation of the GaAs QRs. Microstructural changes of the GaAs QRs were clearly seen in photoluminescence (PL) but barely observable in traditional surface spectroscopy techniques of SEM and AFM. This provides a new pathway to observe the microstructural changes of GaAs QRs growth. PL measurement showed that the emission peaks from the QRs changes from a single sharp peak to two sharp peaks at different stages of formation of the GaAs QRs. The splitting of PL peaks is a result of bimodal distribution of GaAs QRs formed during the droplet epitaxy process. (C) 2013 Elsevier B.V. All rights reserved.