Comparisons of the proton-induced dark current and charge transfer efficiency responses of n- and p-channel CCDs

Abstract

The proton-induced charge transfer efficiency (CTE) behavior for the Lawrence Berkeley National Laboratory (LBNL) p-channel CCD (being developed for the SuperNova Acceleration Probe (SNAP)) is compared with the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3) n-channel CCDs CTE using 55 Fe x-rays, first pixel edge response (FPR), and extended pixel edge response (EPER) techniques. The pre-and post-proton radiation performance parameters of p-channel CCDs designed by LBNL and fabricated at Dalsa Semiconductor, Inc.are compared with nchannel CCDs from E2V, Inc. LBNL p-channel CCDs both with and without notched parallel registers are compared with the E2V CCD43 (a notched, multi-phase pinned (MPP) device) and the E2V CCD44 (an un-notched, non-MPP device), using the same readout timing and measured over the same range of temperatures. The CTE performance of the p-channel CCD is about an order of magnitude better than similar n-channel CCDs for the conditions measured here after a 63 MeV proton fluence of 2.5 x 10 9 cm -2 , which is equivalent to 2.5 years in the HST orbit behind shielding comparable to about 2.5 cm Al. Our measurements are compared with previous CTE measurements at 12 MeV by Bebek et al. [1]. The ~ 10 x CTE improvements relative to n-channel CCDs is seen at -83°C, a temperature which is optimized for n-channel CCD performance. Advantages from p-channel CCDs should be greater at other temperatures. Dark current measurements and hot pixel issues are also discussed.

Proton damage effects in high performance P-channel CCDs

“…The determination of which of Manuscript these two reasons dominates awaits experimental data. Two groups of experimenters have seen a significantly improved hardness in P-CCDs designed for operation at low temperatures and tested at low temperatures [4], [5]. This improvement at low temperature may be partially due to the second order nature of the formation of the divacancy as opposed to the first order nature of the formation of the E-center in N-CCDs, or it may be due to differences in trap re-emission times even at low temperatures.…”

Radiation Tolerance of Fully-Depleted P-Channel CCDs Designed for the SNAP Satellite

“…In the p-channel CCDs, divacancy states are expected to be the dominant hole trap [7]- [9]. It has been predicted that divacancy formation in p-channel CCDs is less favorable than phosphorus-vacancy traps in n-channel CCDs [8], and prior studies have shown improved performance after radiation exposure [7], [10], [11].…”

“…The background from dark current in the cold-irradiated device before the anneal was typically ∼ 10 − 40 e − /pix, while the background in the warm-irradiated devices and in device 4 after annealing was typically ∼ 2 − 8 e − /pix. For comparison, we also include the results of CTE testing on conventional n-channel CCDs from e2v [10] in Figure 4(a). The n-channel CCDs are intended to be used in the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) and were irradiated using 63 MeV protons with a fluence of 2.5 × 10 9 protons/cm 2 and 5 × 10 9 protons/cm 2 , equivalent to 2.5 and 5.0 years in the HST orbit.…”

Proton Damage Comparison of an e2v Technologies n-channel and p-channel CCD204

“…The benefit of using p-channel CCDs to achieve greater displacement damage hardness was originally demonstrated in 1997 [8] and a number of other studies have demonstrated an improved tolerance to radiation-induced CTI when compared to n-channel CCDs [9][10][11][12][13][14], therefore the use of a p-channel CCD was considered for Euclid. However, due to the test readiness level of a suitable p-channel CCD the n-channel CCD273 was selected and the work on p-channel CCDs decoupled from the Euclid programme.…”