Infrared Studies of the Early Stages of Oxygen Clustering in Silicon

Abstract

Clustering of oxygen atoms in silicon in the temperature range 350–470°C will be presented based on results from studies of infrared vibrational absorption bands. Several vibrational bands have been reported in the wavenumber range 975–1015 cm-1. These bands correlate well with the formation of thermal donors (TDs). Bands at 975, 988 and 999 cm-1 have been found to be related to the three first appearing TDs. A band at 1006 cm-1 correlates with the development of the rest of the TDs. The 1012 band is suggested to originate from a different type of donor, possibly the shallow thermal donors. All these bands have a corresponding band in the 716–748 cm-1 range. A broad absorption band with a maximum at 1060 cm-1 a is o grows up during annealing in this temperature range. It is suggested that 90–95% of the oxygen atoms lost from the interstitial position during TD formation gives rise to this band, which originates from a type of oxygen precipitate. Different aspects of the TDs will be presented, such as results from samples doped with the O18 isotope, the bistability of the first two appearing TDs, the influence on the TD formation process from other impurity atoms, from electron irradiation (2 MeV) and from dispersion treatments.