P‐type Czochralski grown (Cz) silicon samples have been irradiated at room temperature (RT), 350, and 450 °C with 1.8 MeV protons to doses of 2×1012and 1×1013 cm‐2 and analyzed by deep level transient spectroscopy (DLTS). The generation rate of interstitial carbon–interstitial oxygen (CiOi) increases with the irradiation temperature, suggesting less efficient annihilation of self‐interstitials and mono‐vacancies at elevated temperature. A defect located at ∼Ev+0.39 eV (Ev denotes the valence band edge) appears in the sample irradiated at 450 °C and also emerges at the expense of CiOi center in the sample irradiated at RT and subsequently heat‐treated above 400 °C. The amplitude of this level is enhanced in the sample irradiated at 450 °C. By comparing the annealing behavior found by photoluminescence (PL) measurements and reported theoretical predictions, the ∼Ev+0.39 eV level is tentatively assigned to the interstitial carbon–oxygen dimer (CiO2i). In addition, other levels at ∼Ev+0.34 eV and ∼Ev+0.58 eV are observed in samples irradiated at 450 °C and RT with heat treatment in the range of 400‐500 °C (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

It is argued in this work that a DLTS signal associated with hole emission from a radiation-induced defect with an energy level at Ev + 0.09 eV is related to a complex of silicon di-interstitial with an oxygen atom (I2O). This signal has been observed in the DLTS spectra of p-type Si:O samples irradiated with either 4-6 MeV electrons or alpha particles. Isochronal and isothermal annealing studies of the samples have shown that the defect responsible for the DLTS signal from the Ev + 0.09 eV level disappears upon heat-treatments in the temperature range 75-100 °C and its formation and annealing behavior is similar to that of a center giving rise to the infrared absorption band at 936 cm-1 previously assigned to a local vibrational mode (LVM) due to the I2O complex. Possible configurations of the I2O complex have been found by ab-initio modeling and analyzed. Formation and binding energies, energy levels and LVMs for different configurations have been determined. It has been found that the minimum energy configuration of the I2O complex consists of the compact I2 to which a divalent interstitial oxygen atom is attached. Calculated values of the strongest LVM (ν = 971 см-1 ) and position of the donor level {Ev + (0.11-0.13) eV} for the minimum energy configuration are very close to those assigned to the I2O defect in the infrared absorption and DLTS experiments.

The formation of the divacancy-oxygen centre (V(2)O) in p-type Czochralski-grown silicon has been investigated by means of deep level transient spectroscopy (DLTS). The donor state (+/0) of V(2)O is located at ~E(v) + 0.23 eV (E(v) denotes the valence band edge) and emerges during heat treatment above 200 °C at the expense of the divacancy centre (V(2)). A concurrent transition takes place between the single-acceptor states of V(2) and V(2)O, as unveiled by the injection of electrons through optical excitation during the trap filling sequence of the DLTS measurements. Further, a defect with an energy level at ~E(v) + 0.09 eV evolves in close correlation with the growth of V(2)O but at a factor of ~5-6 lower in concentration. In the literature, the E(v) + 0.09 eV level has previously been attributed to a double-donor state of V(2)O but this assignment can be ruled out by the present data favouring a complex formed between migrating V(2) centres and a competing interstitial oxygen trap. In addition, a level at ~E(v) + 0.24 eV occurs also during the heat treatment above 200 °C and is tentatively assigned to the trivacancy-oxygen centre (V(3)O).

In this work, a comprehensive study on the transition of divacancy (V 2 ) to divacancy-oxygen (V 2 O) pairs in p-type silicon has been performed with deep level transient spectroscopy (DLTS). Czochralski grown, boron doped p-type, silicon samples, with a doping concentration of 2 Â 10 15 cm À3 and oxygen content of 7.0 6 1.5 Â 10 17 cm À3 , have been irradiated with 1.8 MeV protons. Isothermal annealing at temperatures in the range of 200 C-300 C shows a close to one-to-one correlation between the loss in the donor state of V 2 and the formation of the donor state of V 2 O, located at 0.23 eV above the valence band edge. A concurrent transition takes place between the single acceptor states of V 2 and V 2 O, as unveiled by injection of electrons through optical excitation during the trap filling sequence of the DLTS measurements. Applying the theory for diffusion limited reactions, the diffusivity of V 2 in the studied p-type samples is determined to be (1.5 6 0.7) Â 10 À3 exp[À(1.31 6 0.03) eV/kT] cm 2 /s, and this represents the neutral charge state of V 2 . Further, the data seem to favor a two-stage diffusion mechanism involving partial dissociation of V 2 , although a one-stage process cannot be fully excluded. V C 2014 AIP Publishing LLC.

Photoluminescence (PL) and deep level transient spectroscopy (DLTS) have been used to investigate carbon related defects in p–type Cz–Si induced by proton irradiation. The interstitial carbon–interstitial oxygen (CiOi) level in DLTS and the corresponding C–line (789.5 meV) in PL spectra are detected in as–irradiated samples. Formations of the so–called P–line at 767 meV in PL and a new defect level at about 0.39 eV above the valence band edge, Ev, in the DLTS spectra are observed in the annealed samples. The evolution of the CiOiand Ev+0.39 eV levels in DLTS and also the C– and P– lines in PL upon post–irradiation heat–treatment is investigated, showing that the intensity of the CiOilevel decreases with heat–treatment, which is consistent with the PL data for the C–line. The intensity of the Ev+0.39 eV level is enhanced and then saturates with annealing duration. We tentatively assign this level to the interstitial carbon–oxygen dimer (CiO2i).

Deep level transient spectroscopy (DLTS) has been applied to study the formation of trivacancy-oxygen complexes in Si. Samples of p-type Czochralski grown (Cz) silicon, with a boron doping concentration of ~1x1015cm-3, have been irradiated at room temperature (RT) with 1.8 MeV protons to a dose of 5×1012cm-2. Two new energy levels at Ev+0.24 eV and Ev+0.11 eV (Evdenotes the valence band edge) emerge when the divacancy (V2) to divacancy-oxygen (V2O) transition takes place during post-irradiation annealing. The concentration is ~30% relative to V2(or V2O) and further, the two new levels exhibit an almost one-to-one correlation in strength. The present results strongly support that both levels are related to the same defect with a possible identification as single and double donor states of V3O.

The formation of donor and acceptor states of the trivacancy-oxygen (V 3 O) complex in p-and ntype silicon, respectively, has been studied in detail by means of deep level transient spectroscopy. The samples were irradiated with 1.8 MeV protons, and it was found that acceptor and donor states of V 3 disappear at annealing temperatures below 200 C, with a transition from the metastable (110) planar configuration to the stable fourfold coordinated configuration. Annealing above 200 C unveils the formation of two levels with energy positions at E c À 0.34 eV and E c À 0.46 eV in n-type samples and two levels at E v þ 0.24 eV and E v þ 0.11 eV in p-type samples. (E c and E v denote the conduction and valence band edge, respectively.) The amplitudes of these levels show an almost one-to-one correlation with those of the V 3-related levels occurring after irradiation. In accordance with recent reports in the literature, the emerging levels are ascribed to the V 3 O complex; single and double negative charge states in n-type samples and single and double positive charge states in p-type samples. By undertaking isothermal formation of the V 3 O complex in p-type samples which exhibits first-order kinetics, the diffusivity of V 3 in the neutral charge state is determined to be (8.5 6 3.5) Â 10 À2 exp [À(1.50 6 0.04) eV/kT] cm 2 /s. V