Temperature dependent photoluminescence (PL) spectroscopy was performed on zincblende InGaN/GaN quantum wells (QW), along with PL time decay measurements, in order to estimate the recombination efficiency. The 10K PL spectra was seen to redshift as the QW width was increased (Fig. 2). The 10K decay time increased with increasing QW width, but the intensity was approximately constant (Fig. 3). The integrated intensity of the QWs dropped slowly with temperature up to 100K, and fast up to 300K, with more variation for the single QW (Fig. 4). The PL spectra were all polarised in the [1-10} direction (Fig. S2). The degree of polarisation reduced with increasing QW width (Fig. S3). The PL peak energy shift agrees with a simple finite QW model (Fig. S4).