Trapping and desorption of deuterium during high fluence D-implants of insulators and semiconductors

Abstract

The trapping and desorption of deuterium during high fluence D implantation at 5 keV/atom has been investigated at room temperature in silicon, ilmenite, sapphire and 3 inorganic nuclear track detectors (oligoclase, olivine and glass). These analyses were performed by means of “on-line” techniques already in use for studies of such problems in fusion reactor materials. The comparison of the whole range of solids investigated as yet yields the following conclusions: (i) silicon, sapphire and ilmenite, as well as the varieties of graphite, carbide and nitride previously investigated, would behave like metals at low temperature when diffusion processes are quenched. In particular in these solids there is no reemission of D during implantation up to the critical fluence of about 5 × 10¹⁷ D/cm², corresponding to the onset of a deuterium saturation. In this first family of solids the build-up of the saturation concentrations are satisfactorily described by computer simulations, which just postulate the existence of a critical “maximum” D-concentration typical of a given solid; (ii) in contrast the two alkali-rich inorganic nuclear track detectors start loosing deuterium at much lower implanted fluence (∼ 10¹⁵/cm²). A few preliminary implications of these results in lunar sciences are briefly outlined.