Study of radiation damage in silicon detectors for high ... - F9

90 6. Inuence of Bias VoltageFigure 6.1: First order (red line) and second order (black line) ts for diodes U3A and U3B(unbiased during irradiation and storage). N eff = eq versus heating time at 60 C is displayed.Sam g C g Y k Y (60 C) 2 /ndf kY lin(60C)ple [10 ;2 /cm] [10 ;2 /cm] [10 ;6 /s] [10 ;18 cm 3 /s] 1 st /2 nd [10 ;7 /cms]1 st o. 2 nd o. 1 st o. 2 nd o. 1 st or. 2 nd or. orderU3A 2.4 2.3 4.8 5.5 8.0 4.6 2.1 / 0.4 3.2U3B 2.2 2.1 5.0 5.8 8.4 4.5 2.3 / 0.5 3.4Table 6.1: Fit parameters for reverse annealing of diodes U3A and U3B using rst and secondorder models. Generation rates for defects constant in time (g C ) and for those responsible forreverse annealing (g Y ) are given together with reverse annealing constants k Y 1and kY 2 . 2 /ndfis given for both ts to compare agreement of both models with measured results. Reverseannealing constant kYlin was obtained by the linear t of the ansatz 4.10 during the initial stageof reverse annealing.the treatment, the better agreement of the second order expression cannot be attributedto partial bias. This indicates that another process becomes signicant at the late stageof reverse annealing, with properties still to be determined. It is however not importantfor the LHC operation, where only the initial stage of reverse annealing will take place.The slope of the linear t at the initial stage of reverse annealing at 60 C kY lin (20 C) =(12:4 2) 10 ;10 =cm s can be compared with the slope for unbiased diodes, annealed at20 C kY lin (60 C)=(3:3 0:15) 10 ;7 =cm s (table 4.6). The comparison shows about 270times faster reverse annealing at 60 C compared to 20 C, consistent with an activation