Radiation damage and annealing studies of ion bombarded cobalt

Abstract

The effects of implantation-induced radiation damage on the thermal oxidation of cobalt have been studied. Bombardment by both Co⁺ self-ions and by Xe⁺ has been studied as a function of ion dose, energy and annealing temperature. A major increase in oxidation was observed for doses of >10¹⁶ Co⁺ cm⁻² in agreement with previous studies on Al. The oxidation behaviour as a function of annealing temperature was markedly different for Co⁺ and Xe⁺ bombarded samples. For Co⁺ bombarded samples, damage anneals rapidly in the temperature range 20–300°C due to thermally assisted repair of point defects and vacancy clusters. However, for Xe⁺ bombardment, it is proposed that the higher annealing temperatures required for damage repair arise due to the stabilisation of three-dimensional vacancy clusters by the oversized Xe atoms. The increase in oxidation after annealing in the temperature range 300–500°C is thought to be due to vacancy release mechanisms which may affect oxide nucleation.