Thermal double donor annihilation and oxygen precipitation at around650 °C in Czochralski-grown Si: local vibrational mode studies

Abstract

We have used local vibrational mode (LVM) spectroscopy to monitorthe formation of oxygen-related thermal double donors (TDDs) at450 °C and theirannihilation at 650 °C in carbon-lean Czochralski-grown (Cz-) Si crystals. A few samples were treated at650 °C under high hydrostatic pressure. It is found that the annihilation of TDDs at650 °C results not only in a partial recovery of the interstitial oxygen, but alsoin the appearance of a number of new O-related LVM bands in the range990–1110 cm−1. The positions of these lines and their shapes are identical to thoseobserved for Cz-Si irradiated with electrons or neutrons and annealed at600–700 °C. Since the lines appear upon annealing out ofV O3 and V O4 defects in irradiated samples, they are suggested to arise fromV Om (m>4) complexes. In both kinds of samples, pre-annealed and pre-irradiated,the new LVM bands disappear upon prolonged annealing at650 °C while enhanced oxygen precipitation occurs. TheV Om defects are suggested to serve as nuclei for oxygen precipitates developing at around650 °C. Highhydrostatic pressure is found to enhance further (up to 4–5 times) the oxygen precipitation process at650 °C in the samplespre-annealed at 450 °C.