Ž . Diamond and Related Materials 10 2001 657661 Characterisation of silicon carbide detectors response to electron and photon irradiation M. Bruzzi a,  , F. Nava b , S. Russo c , S. Sciortino a , P. Vanni b a I.N.F.N. Firenze and Dipartimento di Energetica di Firenze, Via S. Marta 3, 50139 Firenze, Italy b Dipartimento di Fisica di Modena and INFN Bologna, Italy c Azienda Ospedaliera Careggi, Firenze, Italy Abstract A preliminary study of the response of SiC devices to 22 MeV electrons and 6 MV photon beams from a linear accelerator is presented in view to assess the feasibility of SiC-based dosimeters. The devices used are 4H SiC epitaxial n-type layers deposited onto a 4H SiC n  -type substrate wafer doped with nitrogen. Schottky contacts have been formed by gold deposition on the epitaxial layer. The released charge has been observed to increase linearly with the electron dose up to 10 Gy. A linear dependence of the current response of the devices has been also observed as a function of the photon dose-rate in the 2  7 Gymin range. A preliminary study of the photoconductive response to UV irradiation of semi-insulating 6H SiC substrates is also reported on samples, with a bulk resistivity of 10 11  cm, produced with a modified Lely technique.  2001 Elsevier Science B.V. All rights reserved. Keywords: Silicon carbide; Semi-insulating SiC; Schottky diode; Photoconductivity 1. Introduction The outstanding optoelectronic properties of wide band-gap semiconductors have stimulated an increas- ing research effort towards different application fields. In particular high band-gap semiconductors such as diamond and silicon carbide have been proposed as an alternative to silicon in semiconductor-based radiation detection devices used in high energy physics experi-   ments 1,2 . In fact, the limited radiation hardness of silicon detectors restricts seriously their operation in  high radiation fields 3 . The properties of CVD dia- mond sensors for particle detection have been investi-  Corresponding author. Tel.: 39-055-4796350; fax: 39-055- 4796342. Ž . E-mail address: bruzzi@fi.infi.it M. Bruzzi .  gated by the RD42 CERN collaboration 1 . Charge collection distances up to 200 m, measured with high quality CVD diamond detectors, shows  10% degra- dation during irradiation up to fluences of  10 15 2  protonscm 4 . Tests on silicon carbide exposed to particle irradiation strongly encourage the use of SiC  devices in severe radiation environments 5 . The limited radiation hardness of silicon presents a drawback in standard on-line dosimeters used in radio- therapy. The silicon dosimeter sensitivity strongly de- pends on the pre-irradiation level, showing a decay of approximately 35% after a 20 MeV electron dose of 3  kGy 6 . Stronger radiation devices for dosimetric appli- cations are presently under study. CVD diamond has been proposed as an alternative to silicon and ionisa- tion chambers as on-line dosimeter in radiotherapy   applications 7  9 , due to its almost tissue-equivalence and to the insensitivity to radiation damage. A draw- 0925-963501$ - see front matter  2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 9 2 5 - 9 6 3 5 00 00380-0