Speaker
Dr
Jaakko Harkonen
(HIP)
Description
Systematic TCT studies (both electron and hole current shapes are measured for each sample) have been carried out on three sets of samples irradiated by 24 GeV protons to fluences ranging from 1.6x1014 to 2.4x1015 p/cm2 (and after 22-day room temperature beneficial anneal): 1) MCZ n-type Si detectors; 2) MCZ p-type Si detectors; and 3) FZ n-type Si detectors (control sample set). For the control sample set, there are no surprises: SCSI has already taken place at the lowest fluence (1.6x1014 p/cm2), and the double junction/double peak effect is readily seen, with the first junction near the p+ contact as the minor one that changes very little with bias voltages, and it is taken over by the second junction near the n+ contact (- space charge) at higher biases than the full depletion voltage. However, for both MCZ n-type and p-type detectors, the double junction/double peak effect starts to take place also at the lowest fluence, and the standard SCSI in n-type detectors (- space charge dominates the entire detector) has not been seen in the fluence range here. But this double junction/peak effect persists into the subsequent higher fluence with about equal junctions near the p+ contact and n+ contact, regardless of bias voltages that may be much larger than the full depletion voltages. This new effect, termed as the Equal-Double-Junction effect is unique only for the 24 GeV proton-irradiated MCZ (n and p) Si detectors, and it is evident by the almost identical TCT current shapes, before trapping corrections, for both electrons (red laser on the p+ contact) and holes (on n+ contact), with the first peak always dominating a small second peak at any biases voltages. After trapping corrections, the two peaks are expected to have about the same heights, indicating an about equal double junction in the detector. TCT data will be fitted in the future to determine the electric field profiles in these detectors.
Author
Dr
Zheng Li
(BNL)
Co-authors
Dr
Elena Verbitskaya
(Ioffe Physico-Technical Institute)
Mr
Esa Tuovinen
(HIP)
Dr
Gabriella Carini
(BNL)
Dr
Jaakko Harkonen
(HIP)
Dr
Panja Luukka
(HIP)
Dr
Vladimir Eremin
(Ioffe Physico-Technical Institute)
Ms
Wei Chen
(BNL)
