Local vibration modes of shallow thermal donors in nitrogen-doped CZ silicon crystals

Local vibration mode (LVM) infrared absorption from shallow thermal donors (STD) composed of nitrogen-oxygen complexes in nitrogen-doped CZ silicon crystals was examined. The samples whose STD concentration had been determined were measured. The sample dependence of the peaks at 810 and 1018cm-1 was similar to that of STD but the estimated concentration was slightly higher. New LVM peaks were found at 855, 973, 982, 1002cm-1 and so on. Their magnitude and sample dependence agreed well with those of STD. Annealing temperature dependence of other samples supported the results. Annealing time dependence of STD concentration at 650 °C was examined. STD peaks at 250, 242 and those at 240, 234 and 238cm-1 behaved differently, suggesting the presence of two kinds of STD origin.