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

4Time Development of DefectsIn this chapter results of the study of time development of radiation-induced defects arepresented. The study consists of measurements of two detector properties these defectscause, full depletion voltage and generation current (bulk reverse current). Time developmentof full depletion voltage (or N eff ) is described by equation 2.65. Since timeconstants for the annealing and reverse-annealing part dier by about two orders of magnitude(around room temperature order of days for annealing compared to about a year forreverse annealing) both phenomena have been studied separately. Due to large amountsof data available for the slow part of annealing (time scale of days at room temperature)[14, 18, 19, 21, 45, 46] this work is only dealing with the fast part (time scale of hours)where data are rather scarce. Results of this study are presented in the rst section. Inthe second section reverse annealing of N eff is discussed with the purpose to determinethe dynamics of responsible processes (rst or second order). Finally, in the third section,results on time development of reverse current are presented.4.1 Fast Annealing of NeffAccording to equation 2.65 and neglecting reverse annealing on the time scale of measurements30 the initial stage of N eff time development can be described byN eff (t) =g C eq + X ig i eq e ;t= i: (4.1)Here g i are introduction rates and i decay time constants of unstable defects and g Cintroduction rate of defects stable in time.30Reverse annealing contributes a few percent of constant level during one week at 15 C and less atlower temperatures.55