Thermal equilibrium and stability of copper complexes in silicon crystal

Formation of the photoluminescence (PL) Cu center (1.014 eV) for silicon crystals diffused with Cu at 700 °C was observed. For the samples with a Cu concentration lower than 1×1014 atom/cm3, almost the same amount of the Cu center was formed for the same concentration of Cu for all the cooling conditions employed without forming Cu precipitation, and the Cu center was very stable for a long storage time at room temperature. More frequent Cu precipitation occurred for the samples with higher Cu concentrations. Quenching of the equilibrium states of the Cu complexes at high temperatures did not occur by rapid cooling. Thermal equilibrium and stability of Cu complexes for the samples containing no Cu precipitates differed from those of the samples containing precipitates.