Fig. 2 (IMAGE) Osaka University Caption Internal quantum efficiency (top) and recombination rates (bottom) as a function of carbon concentration Credit Koshi Sano Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.