Deren Yang

Impact of rapid thermal processing on oxygen precipitation in heavily arsenic and antimony doped Czochralski silicon

A comparative investigation is performed on the effects of vacancies induced by rapid thermal processing on oxygen precipitation behavior in heavily arsenic- and antimony-doped Czochralski silicon wafers. It is experimentally found that vacancy-assisted oxide precipitate nucleation occurs at 800, 900, and 1000u2009u2009°C in the Sb-doped wafers, while it only occurs at 800u2009u2009°C in the As-doped ones. Density functional theory calculations indicate that it is energetically favorable to form AsVO and SbVO complexes in As- and Sb-doped silicon crystals, respectively. These complexes might act as precursors for oxide precipitate nucleation under appropriate conditions. The difference between the effects of rapid thermal processing -induced vacancies on oxide precipitate nucleation in the heavily As- and Sb-doped Cz silicon crystals is tentatively elucidated based on density functional theory calculations revealing the difference in binding energies of AsVO and SbVO complexes.

Scanning infrared microscopy study of thermal processing induced defects in low resistivity Si wafers

Scanning infrared microscopy (SIRM) is used to study thermal processing induced oxygen precipitation in low resistivity n+ and p+ Si substrates doped with As, P, Sb or B. It is shown that SIRM allows us to investigate successfully Si samples with resistivities as low as 1.7xa0mΩ cm and to measure non-destructively bulk micro spectroscopy densities between 107 and 1010 cm−3 with precipitate sizes as small as 30xa0nm. Comparison with precipitation in moderate resistivity reference material that received the same thermal treatments reveals a strong impact of doping for concentrations above 5 × 1018 cm−3, in particular, in combination with rapid thermal processing pre-treatments at temperatures above 1000xa0°C. The observations can be understood by intrinsic point defect trapping during rapid thermal processing and release during subsequent lower temperature treatments through its impact on homogeneous oxide precipitate nucleation.

Erratum: Density functional theory study on the B doping and B/P codoping of Si nanocrystals embedded in SiO2 [Phys. Rev. B 95 , 075307 (2017)]

In the original paper, the beginning of the second paragraph of Sec. I reads “In contrast to the doping of hydrogen-passivated Si NCs, the doping of Si NCs embedded in SiO2 has not been systematically simulated because complicated models need to be used in the simulation [32–35]. Guerra and Ossicini [36] and Carvalho et al. [37] investigated the doping of B and P in Si NCs that were passivated by OH groups.” Here, the statement on the models used by Guerra and Ossicini is not fully consistent with the description in Ref. [36]. In fact, Guerra and Ossicini used Si NCs embedded in SiO2 for the study of B or P single doping and OH-passivated Si NCs for the study of B/P codoping. We would like to point out that no defects such as dangling bonds were at the Si/SiO2 interface in their models of Si NCs embedded in SiO2. But the original paper has highlighted that a dangling bond at the Si/SiO2 interface plays an important role in the doping of Si NCs. In addition, the sizes of Si NCs embedded in SiO2 were up to 1.2 nm (Si47) in Ref. [36], while a size of 1.4 nm (Si71) is used for our Si NCs embedded in SiO2. The larger NC size in our paper is closer to those ( 2.0 nm) routinely obtained in experiments for Si NCs embedded in SiO2. This facilitates a more reliable comparison between calculations and experiments. Please note that the present Erratum does not affect the results and conclusions of our original paper.

Effect of Dopant Compensation on the Behavior of Dissolved Iron and Iron-Boron Related Complexes in Silicon

The behavior of iron, iron-boron (FeB) pairs, and iron-boron-phosphorus (FeB-P) complexes has been studied in B-doped Czochralski silicon with phosphorus (P) compensation and compared with that in uncompensated material. The interstitial iron concentration has been measured at temperatures from 50 to 270°C. The apparent binding energy () of FeB in compensated silicon is (0.25 ± 0.03)u2009eV, significantly lower than the (0.53 ± 0.02)u2009eV in uncompensated silicon. Possible reasons for this reduction in binding energy are discussed by experimental and calculation methods. The results are important for understanding and controlling the behavior of Fe in compensated silicon.

Iron-boron pair dissociation in silicon under strong illumination

The dissociation of iron-boron pairs (FeB) in Czochralski silicon under strong illumination was investigated. It is found that the dissociation process shows a double exponential dependence on time. The first fast process is suggested to be caused by a positive Fe in FeB capturing two electrons and diffusion triggered by the electron-phonon interactions, while the second slow one would involve the capturing of one electron followed by temperature dependent dissociation with an activation energy of (0.21 ± 0.03) eV. The results are important for understanding and controlling the behavior of FeB in concentrator solar cells.

Properties of Multicrystalline Silicon Wafers Based on UMG Material

In this paper, we have studied various properties of UMG silicon wafers by combining four-point probe, microwave photo-conductance decay (μ-PCD), Fourier transform infrared (FTIR) spectroscopy,Inductively coupled plasma-mass spectrometry (ICP-MS) and optical microscopy techniques. The results show that the resistivity and the minority-carrier lifetime of UMG silicon are lower than that of standard multicrystalline material, while the detrimental interstitial iron concentration is larger. The concentration of substitutional carbon, interstitial oxygen and dislocation density are close to that in the standard multi-crystalline silicon. Furthermore, a phosphorous gettering has been used to improve the quality of UMG samples. It is found that phosphorus gettering in UMG silicon can increase the minority carrier lifetime and reduce the interstitial iron concentration. But, the minority-carrier lifetime is still not as high as the conventional/standard silicon counterpart after gettering. These results will help us to better understand the properties of UMG silicon wafer.