Photoluminescence of colour centres in thermally-evaporated LiF films for radiation imaging detectors

Abstract

Lithium fluoride (LiF) is a well-known dosimeter material in pure(McLaughlin et al. Nucl Instrum Methods 175:17–18, 1980) and doped(Lakshmanan et al. Phys Status Solidi (a) 153:265–273, 1996) form. Radiationdetectors based on microcrystalline dispersion of LiF in a polymeric matrix havebeen introduced for gamma and electron high-dose dosimetry (Kovacs et al.Radiat Phys Chem 57:691–695, 2000). In recent years the area of growth andcharacterisation of LiF thin films has seen a considerable expansion. PolycrystallineLiF films grown by thermal evaporation were proposed and tested as nuclear sensorsfor neutrons (Cosset et al. Thin Solid Films 303:191–195, 1997) and for gammadosimetry (Montecchi et al. Point defects in lithium fluoride films induced bygamma irradiation, ch. 116. In: Proceedings of the 7th international conferenceon advanced technology and particle physics, Como, pp 819–825, 2002). In thelast years many efforts have been devoted to the development of novel imagingdetectors for extreme-ultraviolet radiation and soft X-rays (Baldacchini et al. J Nanosci Nanotechnol 3:483–486, 2003), hard X-rays (Almaviva et al. ApplPhys Lett 89(5):054102, 2006), as well as low (Baldacchini et al. J Phys CondensMatter 10:857–867, 1998) and high energy electrons. Such solid-state detectorsare based on the optical reading of photoluminescence (PL) from stable, visibleemittingcolour centres (CCs), produced by irradiation with ionising radiations.