Deep level centers in electron‐irradiated silicon crystals doped with copper at different temperatures

Abstract

The effect of bombardment with energetic particles on the deep‐level spectrum of copper‐contaminated silicon wafers is studied by space charge spectroscopy methods. The p‐type FZ‐Si wafers were doped with copper in the temperature range of 645–750 °C and then irradiated with the 1015 cm−2 fluence of 5 MeV electrons at room temperature. Only the mobile Cui species and the CuPL centers are detected in significant concentrations in the non‐irradiated Cu‐doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in‐diffusion temperature Tdiff. For Tdiff > 700 °C, the irradiation partially reduces the Cui concentration and introduces additional CuPL centers while no standard radiation defects are detected. If Tdiff was below ∼700 °C, the irradiation totally removes the mobile Cui species. Instead, the standard radiation defects and their complexes with copper appear in the deep‐level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed.DLTS spectrum of the Cu‐contaminated and then irradiated silicon qualitatively depends on the copper in‐diffusion temperature.