Optical Studies of Lattice Damage in Neutron-Transmutation-Doped Silicon

Abstract

Infrared spectroscopy (IR) techniques in the 1–50 μm wavelength region have been used to investigate the optical properties of neutron-induced lattice defects in high-purity float-zone (FZ)- refined Si containing ≤10¹⁶ interstitial oxygen (O-_i) cm⁻³ and in high purity Czochralski (Cz)-grown Si containing 2.4 × 10¹⁸ O-_i cm⁻³. The measurements were made following ≤100°C fast neutron (≥ 1 MeV) irradiations and after 20 min isochronal annealing at 50°C intervals from 150 to 900°C.¹ All samples were irradiated in a reactor in- core position with a thermal-to-fast (≥1 MeV) neutron ratio of ∿ 5, so that the lattice damage introduced by thermal neutron absorption and (n, γ) recoils was negligible compared to that introduced by fast neutron collisions with Si atoms.²

Research sponsored by the Division of Materials Sciences, U.S. Department of Energy under contract W-7405-eng-26 with the Union Carbide Corporation.

Experiments performed at the Oak Ridge National Laboratory as a guest scientist.