Carbon-oxygen-self-interstitial complexes were investigated in silicon by means of Fourier transform infrared spectroscopy. Upon irradiation, the CiOi defect (C3) forms which for high doses attract self-interstitials (SiIs) leading to the formation of the CiOi(SiI) defect (C4) with two well-known related bands at 939.6 and 1024 cm−1. The bands are detectable in the spectra both in room temperature (RT) and liquid helium (LH) temperature. Upon annealing at 150 °C, these bands were transformed to three bands at 725, 952, and 973 cm−1, detectable only at LH temperatures. Upon annealing at 220 °C, these bands were transformed to three bands at 951, 969.5, and 977 cm−1, detectable both at RT and LH temperatures. Annealing at 280 °C resulted in the transformation of these bands to two new bands at 973 and 1024 cm−1. The latter bands disappear from the spectra upon annealing at 315 °C without the emergence of other bands in the spectra. Considering reaction kinetics and defect metastability, we developed a model to describe the experimental results. Annealing at 150 °C triggers the capturing of SiIs by the C4 defect leading to the formation of the CiOi(SiI)2 complex. The latter structure appears to be bistable: measuring at LH, the defect is in configuration CiOi(SiI)2 giving rise to the bands at 725, 952, and 973 cm−1, whereas on measurements at RT, the defect converts to another configuration CiOi(SiI)2* without detectable bands in the spectra. Possible structures of the two CiOi(SiI)2 configurations are considered and discussed. Upon annealing at 220 °C, additional SiIs are captured by the CiOi(SiI)2 defect leading to the formation of the CiOi(SiI)3 complex, which in turn on annealing at 280 °C converts to the CiOi(SiI)4 complex. The latter defect anneals out at 315 °C, without being accompanied in the spectra by the growth of new bands.

No abstract

Localized vibrational mode spectroscopy measurements on Czochralski silicon (Cz-Si) samples subjected to isothermal annealing at 450 C are reported. First, we studied the effect of carbon (C) and tin (Sn) isovalent dopants on the aggregation kinetics of oxygen. It is determined that the reduction rate of oxygen is described by the Johnson-Mehl-Avrami equation in accordance with previous reports. The activation energy related with the reaction rate constant of the process is calculated to increase from Cz-Si, to C-doped Cz-Si (CCz-Si), to Sn-doped Cz-Si contained C (SnCz-Si). This is attributed to the presence of the isovalent dopants that may impact both the kinetics of the oxygen atoms and also may lead to the formation of other oxygen-related clusters. Second, we studied the effect of Sn on the formation and evolution of carbon-oxygen (C-O) defects. It was determined that the presence of Sn suppresses the formation of the C-O defects as indicated by the reduction in the strength of the 683, 626, and 586 cm À1 well-known bands of C s O i defect. The phenomenon is attributed to the association of Sn with C atoms that may prevent the pairing of O with C. Third, we investigated the effect of C and Sn on the formation of thermal donors (TDs). Regarding carbon our results verified previous reports that carbon suppresses the formation of TDs. Interestingly, when both C and Sn are present in Si, very weak bands of TDs were observed, although it is known that Sn alone suppress their formation. This may be attributed to the competing strains of C and Sn in the Si lattice. V

Nitrogen is a key dopant in Czochralski silicon (Cz-Si) widely used to control properties of Si wafers for applications in the microelectronics industry. Most of

We investigated, experimentally as well as theoretically, defect structures in electron irradiated Czochralski-grown silicon (Cz-Si) containing carbon. Infrared spectroscopy (IR) studies observed a band at 1020 cm−1 arisen in the spectra around 300 °C. Its growth occurs concomitantly with the decay out of the well-known vacancy-oxygen (VO) defect, with a Local Vibrational Mode (LVM) at 830 cm−1 and carbon interstitial-oxygen interstitial (CiOi) defect with a LVM at 862 cm−1, in silicon (Si). The main purpose of this work is to establish the origin of the 1020 cm−1 band. One potential candidate is the carbon interstitial-dioxygen (CiO2i) defect since it is expected to form upon annealing out of the CiOi pair. To this end, systematic density functional theory (DFT) calculations were used to predict the lowest energy structure of the (CiO2i) defect in Si. Thereafter, we employed the dipole–dipole interaction method to calculate the vibrational frequencies of the structure. We found that CiO2i defect has an LVM at ~1006 cm−1, a value very close to our experimental one. The analysis and study of the results lead us to tentatively correlate the 1020 cm−1 band with the CiO2i defect.

No abstract

No abstract

No abstract