Thin detectors have been proposed to investigate the possibility to get a constant and low depletion voltage and to limit the leakage current of heavily irradiated silicon devices. In this work we compare a thin, 58 µm thick [1] and a typical, 300 µm thick silicon detector. We consider a high resistivity, 7× 1011 cm− 3 n-doped substrate. In order to investigate the performances of these structures, simulations have been carried out using the ISE-TCAD DESSIS device simulator. We consider evenly irradiated structures. The so called three-level model [2] has been used to investigate the effects of the radiation fluence on the electric field and the current of thin and typical silicon structure with an equivalent fluence of 2× 1014 cm− 2 1MeV neutrons. Moreover, the electric field of a thin non irradiated structure and a thin irradiated structure are compared using the same fluence.