New method to determine the carbon concentration in silicon

Silicon samples subjected to a CF4 reactive ion etch exhibit the G-line luminescence known from photoluminescence studies of irradiation damage in Si. We investigate the mechanism of low-energy carbon implantation by CF4 plasma and find a linear dependence of the G-line luminescence intensity on the substitutional carbon concentration in the samples. By a standardized etching and photoluminescence procedure, we expect to determine carbon concentrations two orders of magnitude smaller than the ASTM infrared absorption method.