Radiation Measurements 43 (2008) 379 – 382 www.elsevier.com/locate/radmeas Thermoluminescence properties of undoped and nitrogen-doped CVD diamond exposed to gamma radiation M. Barboza-Flores a , * , S. Gastélum a , E. Cruz-Zaragoza b , R. Meléndrez a , V. Chernov a , M. Pedroza-Montero a , A. Favalli c a Centro de Investigación en Física, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83190, México b Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. P. 70-543, México D.F. 04510, México c European Commission, Joint Research Centre, Institute for the Protection and the Security of the Citizen, TP800, Via E. Fermi, I-21020 Ispra, Italy Abstract It is known that the thermoluminescence (TL) performance of CVD diamond depends on the impurity concentration and doping materials introduced during growing. We report on the TL properties of undoped and 750 ppm nitrogen-doped CVD diamond grown on (0 0 1) silicon substrate. The samples were exposed to gamma radiation from a Gammacell 200 Nordion irradiator in the 10–500 Gy dose range at 627 mGy/min dose rate. The nitrogen-doped CVD diamond sample exhibited a TL glow curve peaked around 537 K and a small shoulder about 411 K and a linear dose behavior in the 10–60 Gy dose range. In contrast, the undoped specimen showed a 591 K peaked TL glow curve and linear dose response for 10–100Gy doses. However, both samples displayed a non-linear dose response for doses higher than 100Gy. The doping effects seem to cause a higher TL efficiency, which may be attributed to the differences in the diamond bonding and amorphous carbon on the CVD samples as well as to the presence of nitrogen. In addition, the nitrogen content may produce some structural and morphological surface effects, which may account for the distinctive TL features and dose response of the diamond samples. © 2007 Elsevier Ltd. All rights reserved. Keywords: Thermoluminescence; CVD diamond films; Dosimetry 1. Introduction Chemical vapour depositions (CVD) of diamond films are considered excellent prospects for thermoluminescence (TL) dosimetry involving ionizing and non-ionizing radiation fields. There is reliable information related to the effect of doping im- purities on the TL properties of diamond radiation detectors (Nam et al., 1991; Keddy and Nam, 1993; Furetta et al., 1999). Optimization of the TL properties depends on the type and con- tent of doping incorporated into the CVD precursor gas during growth of the diamond films. Impurity doping of CVD dia- mond has been the subject of intensive research, where nitrogen has drawn particular attention, mainly due to the effects of low concentrations on improving the TL sensitivity and dose linear- ity (Benabdesselam et al., 2001; Descamps et al., 2006). The * Corresponding author. Tel.: +52 662 259 2156; fax: +52 662 212 6649. E-mail address: mbarboza@cajeme.cifus.uson.mx (M. Barboza-Flores). 1350-4487/$ - see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2007.11.055 TL enhancing efficiency through doping incorporation is far of being an obvious problem, since the TL of undoped CVD dia- mond films are strongly dependent on the precursor gas com- ponents and concentrations, substrate temperature, and other instrumental parameter during film deposition. As a result, the diamond film may develop very distinctive morphological and structural defects, which will affect the charge trapping and the thermally stimulated radiative recombination associated to the TL phenomenon. In addition, nitrogen traces (few ppm)—even in undoped material—may be present in the CVD diamond film due to air leaks and reactants impurities. In the present work, we present results on the TL properties and dose behaviour of nitrogen-doped (750 ppm) and undoped CVD diamond films exposed to gamma radiation in the range of 10–500Gy. The same samples were previously examined subjected to UV and beta radiation, and showed excellent TL properties (Preciado-Flores et al., 2005, 2006). The results point towards the advantage of having high quality CVD dia- mond films, tissue equivalent, chemically inert, radiation hard,