Particle detectors made of high-resistivity Czochralski silicon

We have processed pin-diodes and strip detectors on n- and p-type high-resistivity silicon wafers grown by magnetic Czochralski method. The Czochralski silicon (Cz-Si) wafers manufactured by Okmetic Oyj have nominal resistivity of 900 Omega cm and 1.9 kOmega cm for n- and p-type, respectively. The oxygen concentration in these substrates is slightly less than typically in wafers used for integrated circuit fabrication. This is optimal for semiconductor fabrication as well as for radiation hardness. The radiation hardness of devices has been investigated with several irradiation campaigns including low- and high-energy protons, neutrons, gamma-rays, lithium ions and electrons. Cz-Si was found to be more radiation hard than standard Float Zone silicon (Fz-Si) or oxygenated Fz-Si. When irradiated with protons, the full depletion voltage in Cz-Si has not exceeded its initial value of 300 V even after the fluence of 5 multiplied by 10**1**4 cm**-**2 1-MeV eq. n cm **-**2 that equals more than 30 years operation of strip detectors in LHC experiments

Annealing study of oxygenated and non-oxygenated float zone silicon irradiated with 15 MeV protons

Introducing oxygen into the silicon material is believed to improve the radiation hardness of silicon detectors. In this study, oxygenated and non-oxygenated silicon samples were processed and irradiated with 15 MeV protons. In order to speed up the defect reactions after the exposure to particle radiation, the samples were heat treated at elevated temperatures. In this way, the long-term stability of silicon detectors in hostile radiation environment could be estimated. Current-voltage measurements and Surface Photovoltage (SPV) method were used to characterize the samples

The effect of oxygenation on the radiation hardness of silicon studied by surface photovoltage method

The effect of oxygenation on the radiation hardness of silicon detectors was studied. Oxygen-enriched and standard float-zone silicon pin-diodes and oxidized samples were processed and irradiated with 15-MeV protons. After the irradiations, the surface photovoltage (SPV) method was applied to extract minority carrier diffusion lengths of the silicon samples. Adding oxygen to silicon was found to improve the radiation hardness of silicon. The effect was visible in minority carrier diffusion lengths as well as in reverse bias leakage currents. The suitability of SPV method for characterizing irradiated silicon samples was proved. 14 Refs

Experimental Linear Energy Transfer of Heavy Ions in Silicon for RADEF Cocktail Species

Experimental linear energy transfer values of heavy ions in silicon are presented with comparison to estimations from different semi empirical codes widely used among the community. This paper completes the experimental LET data for the RADEF cocktail ions in silicon

Linear energy transfer of heavy ions in silicon

Researchers performing radiation testing on electronic components often rely on semi-empirical prediction codes for determining the linear energy transfer (LET) (or electronic stopping force) of ions, without paying much attention to their reliability. However, it is seen that estimations calculated with different codes can have over 10% discrepancies, especially in the case of heavy ions with higher LET (e.g., xenon). As a consequence of the modern component fabrication techniques this has become an important issue when studying the radiation durability of electronics. In order to clarify this inconsistency, LET measurements for Xe-131 and Kr-82 in silicon have been undertaken and obtained results are presented, discussed and compared with earlier predicted data