Priming effect on a polycrystalline CVD diamond detector under 60Co γ-rays irradiation

Characterization of silicon carbide and diamond detectors for neutron applications

“…The D-SC, D-PC and SiC-SI detectors have all demonstrated some form of the so-called polarization effect during irradiation, i.e. a change in the acquired spectrum and/or count rate with time [27,[41][42][43]. This particular effect is prevalent in low-doped, wide-bandgap semiconductors (D [44], SiC [45], CdZnTe [46] and CdTe [47]) and is a result of charge carriers being trapped for long periods of time, leading to a change in the space-charge distribution [36].…”

“…This is a result of charge carriers being trapped in deep-level locations for long periods of time, leading to a change in the space-charge region, and is very dependent upon the density of ionization within the detectors, with radiation that results in a large ionization concentrations in a small volume (such as alpha particles) producing very quick polarization effects, as demonstrated in figure 7. This is because these particles tend to create a large concentration of charge carriers at shallow depths within the detector (≈17 μm for diamond and ≈18 μm for SiC [53]), resulting in a high trapping rate over a small region [41][42][43]. This leads to the creation of a localized spacecharge barrier close to the electrode, through which further electrons and holes must pass to be fully collected.…”

Alpha radiation induced space charge stability effects in semi-insulating silicon carbide semiconductors compared to diamond

“…Within some wide band gap semiconductor materials (particularly Diamond) priming is often employed as a way of stabilizing the polarisation effect within the material [11] [12][42] [43]. This process involves irradiating the detector to high doses (usually in the region or 5-20Gy [43]) in order to saturate the detector with a large electron-hole concentration, a significant proportion of which are then captured by the deep level traps.…”

“…By applying a higher bias, the created charge carriers can overcome any space charge variation and be fully collected at the electrodes. Furthermore, as the trapped charges are immobile for relatively long periods of time (provided the carriers are not detrapped through heating, light etc) the response remains very stable over reasonable periods of time [12]. This method of controlling polarisation is inconvenient for many applications as it requires significant doses to the detector and only solves the issues associated with deep level traps, with shallow trap polarisation effects still being present.…”

“…These management methods allow for the stable use of semiinsulating SiC material in practical radiation detection applications. As a benchmark, similar studies were carried out on single crystal diamond (D-SC) and polycrystalline diamond (D-PC), both of which have well documented polarisation phenomena for radiation detection applications [11] [12] [13] [14].…”