Mechanism for fast neutron damage of Ge(HP) detectors
1980; Elsevier BV; Volume: 171; Issue: 1 Linguagem: Inglês
10.1016/0029-554x(80)90008-7
ISSN1878-3759
AutoresL. S. Darken, Rex C. Trammell, T. W. Raudorf, Richard H. Pehl, Jack H. Elliott,
Tópico(s)Advanced Semiconductor Detectors and Materials
ResumoThe effect on high purity germanium detectors of the disordered regions (r ∼ 100 Å) created by fast neutrons is theoretically and experimentally addressed. The hole trapping cross section of these defects is a function of their net negative charge and the applied electric field. We estimate σ ≈ 10−9 – 10−10 cm2 immediately after biasing an n-type detector and σ ≈ 10−10 – 10−12 cm2 as hole trapping and detrapping reach a steady state in the depleted detector. Resolution transients observed immediately after biasing n-type and p-type Ge(HP) coaxial detectors are reported and are shown to be consistent with the neutralization (n-type) or the charging (p-type) of the thermal equilibrium state. However on the basis of these transients we cannot exclude the possibility that point defects play a decisive role in the steady state resolution degradation. The ionization or activation of traps after cycling the p-type detector off/on can be consistently interpreted as due to an acceptor level near Ev + 0.27 eV. The duration of the transient observed in n-type germanium was reduced to less than 1 h by placing a 6.5 μCi 60Co source on the end cap. Thus this transient does not significantly diminish the advantage of the contracting polarity employed on n-type coaxial detectors in reducing the effect of the hole trapping on resolution.
Referência(s)