Localized Mode of Substitutional Carbon in Ion-Implanted Silicon

Abstract

Substitutional carbon, C_S, incorporated into silicon by C-ion implantation has been investigated using the localized vibrational mode for C_S as a monitor. A C_S/C fraction of 0.2 was observed for a uniform dopant profile obtained by a multiple energy implant at room temperature (4.7, 7.7, and 10.10¹⁴ C⁺/cm² at 60, 140, and 260 keV, respectively). C_S/C increased to ~0.75 upon annealing to 500°C. Absence of an observable C_S after 7 · 10¹⁵ 200 keV C⁺/cm² at room temperature is ascribed to the high degree of disorder in the implanted layer. C_S was observed in this high fluence implanted sample after annealing to 500 °C. An additional low fluence implantation of an annealed C-implanted layer decreased C_S, consistent with a Si replacement mechanism.

This work was supported by the U.S. Atomic Energy Commission.