PHOTOLUMINESCENCE MEASUREMENT OF CARBON IN SILICON-CRYSTALS IRRADIATED WITH HIGH-ENERGY ELECTRONS

A high energy electron irradiation-photoluminescence (PL) technique is employed for developing an analytical method for determining the conc entration of carbon in silicon crystals. Particular attention is paid to the effect of oxygen concentration on the PL intensity. The intensi ty of the 0.790 eV PL peak (C-line) due to the complex C-l-O-l (I: int erstitial) formed by electron irradiation can be used to measure the l owest levels of 10(14) to 10(15) atom/cm(3) of carbon, almost independ ently of oxygen concentration. The intensity of the 0.969 eV peak (G-l ine) due to the complex C-s-Si-l-C-s (S: substitutional) is highly aff ected by the oxygen concentration. When the oxygen concentration in th e crystal is known, by using this peak, carbon concentrations or 10(16 ) to 10(17) atom/cm(3) can be determined within an uncertainty of +/-3 0%. By using both PL peak intensities and theoretical curves obtained from the rate equations of the complex formation, it is possible to de termine carbon concentrations in the 10(14) to 10(17) atom/cm(3) range .