Charge collection and trapping in low-temperature silicon detectors
- Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)
- Department of Physics, Santa Clara University, Santa Clara, California 95053 (United States)
Charge collection efficiency measurements in silicon detectors at low temperature ({ital T}{lt}0.5 K) and low applied electric field ({ital E}=0.1{endash}100 V/cm) were performed using a variety of high-purity, {ital p}-type silicon samples with room-temperature resistivity in the range 2{endash}40 k{Omega}cm. Good charge collection under these conditions of low temperature and low electric field is necessary for background suppression, through the simultaneous measurement of phonons and ionization, in a very low event rate dark matter search or neutrino physics experiment. Charge loss due to trapping during drift is present in some samples, but the data suggest that another charge{endash}loss mechanism is also important. We present results which indicate that, for 60 keV energy depositions, a significant fraction of the total charge loss by trapping occurs in the initial electron-hole cloud near the event location which may briefly act as a shielded, field-free region. In addition, measurements of the lateral size, transverse to the applied electric field, of the initial electron-hole cloud indicate large transverse diffusion lengths. At the lowest fields a lateral diameter on the order of 1 mm is found in a detector {approximately}5 mm thick. {copyright} {ital 1996 American Institute of Physics.}
- DOE Contract Number:
- FG03-90ER40569
- OSTI ID:
- 284252
- Journal Information:
- Journal of Applied Physics, Vol. 79, Issue 11; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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