Chemical implantation, isotopic trapping effects, and induced hygroscopicity resulting from 15 keV ion bombardment of sapphire

Publisher Website
Google Scholar
Abstract
Targets of single crystal sapphire (α‐Al2O3) have been bombarded with 15 keV H+, D+, He+, Ne+, and Ar+. The H+ and D+ chemically implant, as indicated by the production of ir absorption bands at 3400 and 2450 cm−1, attributed to the hydroxyl and deuteroxyl stretching frequencies, respectively. At ion fluences of 1×1017 cm−2 the chemical trapping efficiency of D+ as calculated from the integrated deuteroxyl band intensity is of the order of unity. The number of D+ chemically trapped as deuteroxyl saturates at about 2×1017 cm−2 of target surface area, and at higher D+ fluences physical trapping of deuterium in gas blisters becomes the dominant trapping mechanism. By contrast, chemical trapping of H+ saturates at about 7×1016 cm−2. This isotopic effect can be rationalized in terms of the greater displacement damage resulting from D+ bombardment. The surfaces of sapphire targets subjected to 15 keV H+, D+, and He+ bombardments at fluences above 2×1017 cm−2 exhibit an induced hygroscopicity characterized by a growing hydroxyl band absorption on exposure to water vapor. Blisters indicative of physical trapping are observed for H+ and He+ as well as for high fluence D+ bombardments. There is no evidence of blistering or induced hygroscopicity due to Ne+ or Ar+ bombardments. The results for H+ and D+ are extrapolated to T+ and the implications for chemical sputtering are considered.