Oxygen '96

Early Stages of Oxygen Precipitation in Silicon

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METASTABLE INTERSTITIAL SILICON-INTERSTITIAL OXYGEN COMPLEX IN SILICON

Kh. A. Abdullin, B. N. Mukashev, and Yu. V. Gorelkinskii

Physical Technical Institute, Academy of Sciences of Kazakstan, 480082, Almaty, 82, Kazakstan

Keywords: metastability, radiation defect, oxygen, silicon, EPR, interstitial

We report the results of an EPR study of a single crystal of pulled silicon. After 30 MeV proton irradiation at 77 K, a metastable complex is observed. The complex has two different configurations labelled A and B. The known EPR centre A18 [1] arises from the A⁺ configuration with C_1h symmetry. The new EPR centres AA13 and AA14 arise from B⁺ (C_3v) and B^- (C₁) configurations respectively. The spin-Hamiltonian parameters for the spectra are determined. The observed ²⁹Si hyperfine interaction for the A18 and AA13 spectra allow us to classify metastable complex as an interstitial-related defect. Completely reversible A <-> B conversions is observed at ~160 K (A->B) and at 77 K under band gap illumination (B->A). Configurational-coordinate energy curves are determined from conversion kinetics. The metastable complex anneals at ~250 K.

Uniaxial stress experiments were made for the metastable complex. It is found that the defect energy is reduced when the AA13 defect is compressed in the direction along <111> (g_parallel and A_parallel) axes. Also an "as-grown" sample was subjected to <110> stress at ~450 degrees C before 77 K proton irradiation. It was found that the alignment of A18 and AA13 defect has the same character as for <111> oriented oxygen interstitial. A tentative model for the metastable complex includes silicon-interstitial and oxygen-interstitial atoms. This model is consistent with the properties of the EPR data and stress alignment results.

[1] Y.H. Lee, J.C. Corelli, and J.W. Corbet, Physics Letters 60A (1977) 55.

Last modified: Mon Feb 19 12:11:10 GMT 1996 JG