- Email: [email protected]
Single particle transient response and displacement damage in CMOS image sensors induced by high energy neutrons at Back-n in CSNS facility
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Single particle transient response and displacement damage in CMOS image sensors induced by high energy neutrons at Back-n in CSNS facility Zujun Wang a,b ,∗, Yuanyuan Xue a , Wei Chen a ,∗, Hao Ning b , Rui Xu b , Xiaoqiang Guo a , Jiangkun Sheng a , Zhibin Yao a , Baoping He a , Wuying Ma a , Guantao Dong a a b
State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an, China School of Materials Science and Engineering, Xiangtan University, Hunan, China
ARTICLE
INFO
Keywords: Spallation neutron source CMOS image sensor (CIS) Single particle transient response Displacement damage Neutron radiation
ABSTRACT Neutron radiation experiments of the complementary metal-oxide semiconductor (CMOS) image sensors (CISs) at back-streaming white neutrons (Back-n) in China Spallation Neutron Source (CSNS) facility are presented. The displacement damages induced by neutron radiation are characterized by the analysis of the increase of dark signal and dark signal non-uniformity, and the occurrences of dark signal spike and random telegraph signal (RTS). The two-level and multi-level RTS behaviors induced by neutron displacement radiation are presented. The mechanisms of the dark signal spikes and RTS induced by neutron displacement radiation are analyzed respectively. The single particle transient response characterizations are described by analyzing the online dark images during neutron radiation. The mechanisms of the dark signal spikes and the white lines induced by the single transient neutron events are also demonstrated by analyzing the interactions between the higher energy neutrons and bulk silicon lattices of CISs.
1. Introduction China Spallation Neutron Source (CSNS) facility provides a large scientific platform. The back-streaming white neutrons (Back-n) from a spallation target through the proton beam line in CSNS facility has a very wide neutron energy spectrum [1], which can be used to perform neutron radiation. Radiation effects in a complementary metal-oxide semiconductor (CMOS) image sensor (CIS) induced by gamma rays, X rays, protons, and neutrons have been widely investigated for their applications in space radiation or nuclear radiation environments [2– 5]. However, the investigations are mainly focused on the total ionizing dose damage and the displacement damage, and fewer studies have focused on the single particle transient response and displacement damage in CISs induced by high energy neutrons. No literatures have reported the above researches at Back-n in CSNS facility. The primary goal of this paper is to present the radiation experiments of the CISs at Back-n in CSNS. First, we introduce the experimental setup and the sample. Second, we investigate the neutron displacement damages by the analysis of the increase of dark signal and dark signal non-uniformity (DSNU), and the occurrences of dark signal spike and random telegraph signal (RTS). Third, we describe the single particle transient response characterizations and the mechanisms of the
occurrences of dark signal spikes and white lines induced by the single transient neutron events. 2. Experimental details The neutron radiation experiments were carried out at Back-n in CSNS facility (Dongguan, China). The schematic layout of the Back-n in CSNS facility [6] is shown in Fig. 1 and the neutron radiation position is located at endstation2 (ES#2, 80 m). The photo of the experimental setup at Back-n in CSNS facility is shown in Fig. 2. The neutron energy spectrum at Back-n in CSNS facility ranges from 1eV to 200 MeV and the detailed spectrum of Back-n beamline is shown in [7]. The neutron flux at the exposure position (ES#2) is about 1.4 × 106 n/(cm2 s) in these radiation experiments. The online tests were carried out to observe the single particle transient response during radiation. The offline tests were carried out to investigate the displacement damage. The neutron fluences of the off-line tests include 1.12 × 1010 , 1.69 × 1010 , 2.80 × 1010 , and 3.36 × 1010 n/cm2 . All the tests were performed at room temperature about 25 ◦ C. The CIS type used in these experiments is a Sony IMX249. The image size is diagonal 13.4 mm (type 1/1.2). The unit cell size is
∗ Corresponding author at: State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an, China. E-mail addresses: [email protected] (Z. Wang), [email protected] (W. Chen).
https://doi.org/10.1016/j.nima.2018.12.033 Received 11 October 2018; Received in revised form 24 November 2018; Accepted 9 December 2018 Available online 25 December 2018 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 1. Schematic layout of Back-n in CSNS facility [6].
5.86 μm × 5.86 μm. The resolution is 1920 × 1200. The ADC output is 12 bits. The readout method is the global shutter which can scan all pixel signals at once. The max frame rate is 30 frame/s. 3. Results and discussion 3.1. Displacement damage induced by neutrons Neutron radiation mainly induces displacement damage by elastic and inelastic interactions between the neutron beam and the bulk silicon lattices of a CIS. The total ionizing dose (cumulative ionizing) damage induced by neutron radiation in a CIS is very small and can be negligible. The typical characterizations of displacement damage in a CIS are presented by the analysis of the increase of dark signal and DSNU, and the occurrences of dark signal spikes and RTS. Dark signal spikes represent the individual pixels with dark signal level obviously higher than the ordinary pixels in irradiated or unirradiated pixel regions. Fig. 3 shows the dark signal spikes increase with increasing neutron radiation fluence. The occurrences of dark signal spikes are mainly due to stable bulk defects in the space charge region (SCR) of a CIS induced by neutron displacement damage. The unit of dark signal is DN (digital number). Fig. 4 shows the histograms of dark signal distributions versus neutron radiation fluence. From the dark signal distributions as shown in Fig. 4, we can observe that the
Fig. 2. The experimental setup at Back-n in CSNS facility.
number and amplitude of dark signal spikes increase with increasing neutron radiation fluence. However, the noticeable impacts on the dark
Fig. 3. The dark signal spikes increase with increasing neutron radiation fluence.
69
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Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 4. Histograms of dark signal distributions versus neutron radiation fluence.
Fig. 6. Typical two-level RTS in a CIS induced by neutron radiation.
Fig. 5. The dark signal and DSNU versus neutron radiation fluence.
Fig. 7. Typical multi-level RTS in a CIS induced by neutron radiation.
signals are not shown in all the pixels in the CIS. Neutron radiation impacts a part of the pixels because the interactions between the neutron beams and the bulk silicon lattices have very small cross section. These interactions create bulk defects in silicon of a CIS and subsequently induce the increase of dark signal and the occurrences of dark signal spikes [5]. The occurrences of dark signal spikes result in the increase of dark signal and DSNU of a CIS. DSNU is the non-uniformity of a dark image, which originates from the different output charge signals from one pixel to another in the solid state image sensors [2,8]. Fig. 5 shows the dark signal and DSNU versus neutron radiation fluence. The increase of dark signal is due to the Shockley–Read–Hall (SRH) generation in the SCR induced by the stable bulk defects [9]. The increase of DSNU is due to the occurrences of dark signal spikes and RTS induced by neuron displacement damage, which increases the non-uniformity of dark signals. RTS is a phenomenon that the dark signal switches randomly between two or more discrete states [10]. RTS in a CIS represents the dark signal fluctuation with time in the pixels. This phenomenon can be observed as pixel blinking in a series of dark images, which will influence the calibration of a CIS by impacting the noise performance. Protoninduced RTS has been reported in the literatures [11–13], however little previous work [10] has focused on neutron-induced RTS in a CIS. Fig. 6 shows the typical two-level RTS in a CIS induced by neutron radiation at Back-n in CSNS. The mean values and the standard variations of dark signals in the selected pixels are also presented. Fig. 7 shows the typical multi-level RTS of a CIS induced by neutron radiation at Back-n in CSNS. From Figs. 6 and 7, the RTS behaviors in the different pixels
of a CIS show the obvious differences because the displacement damage in the pixels is various. Highly degraded pixels exhibit large transition amplitudes as shown in Figs. 6 and 7. Before radiation, the RTS behavior in a CIS is very small. After neutron radiation, the RTS behavior in a CIS shows two-level or multilevel RTS. Bulk defects such as point defects and cluster defects induced by neutron radiation are mainly located in the SCR of a CIS. These bulk defects with energy level within the bandgap behave as classical SRH generation–recombination mechanism, which induces dark signal fluctuation with time in the pixels. We speculate that point defects capture charge and then release it with time in the pixels, which usually induces the signal output to switch between two discrete levels. Cluster defects can form several SRH generation–recombination centers, which may induce the signal output to switch between several discrete levels. Thus, the two-level RTS behaviors may be mainly due to point defects induced by neutron radiation. However, the multi-level RTS behaviors may be mainly due to cluster defects induced by neutron radiation. 3.2. Single particle transient response induced by neutrons The single particle transient responses induced by neutrons at Backn in CSNS are observed during radiation. The typical characterizations exhibit occurrences of dark signal spikes (not persistent) and bright lines. These responses are not permanent and disappear after radiation immediately. The responses are also randomly distributed in the dark images during radiation. The subimages of 100 × 100 pixels are extracted from the dark images of 1920 × 1200 to investigate the single particle transient responses. Fig. 8 shows the typical transient responses 70
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 8. The typical transient responses induced by neutron events: sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams with the elimination of the dark signal induced by displacement damage: (a) shape 1, (b) shape 2, (c) shape 3, (d) shape 4.
Fig. 9. Sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams at continuous frames with the same radiation states: (a) before radiation, (b) 01th frame, (c) 02th frame, (d) after radiation.
response are the occurrences of dark signal spikes (not persistent) and bright lines during neutron radiation. The dark signal spikes and the bright lines originate from the transient ionizing charges collected in a single pixel or several adjacent pixels. Both the dark signal spikes and the bright lines are not persistent and the characterizations of the bright lines depend on the transient ionizing of transport traces of the secondary particles. More experiments irradiated by high energy protons and neutrons will be carried out in the future to further investigate the single particle transient response and displacement damages in CISs.
induced by neutron events. Sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams with the elimination of the dark signal induced by displacement damage exhibit the different shape of the bright lines. Fig. 9 shows the sets of dark subimages (inversion of black and white color) of a CIS exposed to the neutron beams at continuous frames with the same radiation states: (a) before radiation, (b) 01th frame, (c) 02th frame, (d) after radiation. Before radiation, there is no dark signal spikes and bright lines. However, a large number of the dark signal spikes and the bright lines appear during radiation as shown in Figs. 9(b) and 9(c). After radiation, there are still many dark signal spikes as shown in Fig. 9(d), which is due to the displacement damage. In contrast to the dark signal spikes of single particle transient responses, these dark signal spikes always exist and have fixed position. The experiments show that the higher energy neutrons at Backn in CSNS will induce the transient neutron events during radiation. The interactions between the higher energy neutrons and the bulk silicon lattices of a CIS induce the secondary particles which can ionize electron–hole pairs in the transport trace during radiation. The transient neutron events may exist in a single pixel or several adjacent pixels. The transient ionizing charges collected in a single pixel result in a dark signal spike. The transient ionizing charges collected in several adjacent pixels result in a bright line. Both the dark signal spikes and the bright lines are not persistent and depend on the transient ionizing of transport traces of the secondary particles. Fig. 9 shows the single particle transient responses are also randomly distributed.
Acknowledgments This work was supported by the National Science Foundation of China (Grant No. 11875223, 11805155, 11690043), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA15015000), the Innovation Foundation of Radiation Application, China (Grant No. KFZC2018040201), and the Foundation of State Key Laboratory of China (Grant No. SKLIPR1803, 1610). The authors gratefully acknowledge all members of CSNS-WNS for their earnest support and help during the work. References [1] H.T. Jing, J.Y. Tang, H.Q. Tang, H.H. Xia, T.J. Liang, Z.Y. Zhou, Q.P. Zhong, X.C. Ruan, Nucl. Instrum. Methods A 621 (2010) 91. [2] Z.J. Wang, W.Y. Ma, J. Liu, Y.Y. Xue, B.P. He, Z.B. Yao, S.Y. Huang, M.B. Liu, J.K. Sheng, Nucl. Instrum. Methods A 820 (2016) 89. [3] D. Doering, M. Deveaux, M. Domachowski, C. Dritsa, I. Froehlich, M. Koziel, C. Muentz, S. Ottersbach, F. M.Wagner, J. Stroth. Nucl. Instrum. Methods A 658 (2011) 133. [4] V. Goiffon, P. Magnan, O. Saint-Pe, F. Bernard, G. Rolland, Nucl. Instrum. Methods A 610 (2009) 225. [5] C. Virmontois, V. Goiffon, P. Magnan, S. Girard, O. Saint-pe, S. Petit, G. Rolland, A. Bardoux, IEEE Trans. Nucl. Sci. 59 (2012) 927. [6] Z.X. Tan, J.Y. Tang, H.T. Jing, R.R. Fan, Q. Li, C.J. Ning, J. Bao, X.C. Ruan, G. q.Luan, C.Q. Feng, X.P. Zhang, Nucl. Instrum. Methods A 889 (2018) 122. [7] Z. Tan, J. Tang, H. Jing, R. Fan, Q. Li, C. Ning, J. Bao, X. Ruan, G. Luan, C. Feng, X. Zhang, Energy-resolved fast neutron resonance radiography at CSNS, Nucl. Instrum. Methods A (2018) http://dx.doi.org/10.1016/j.nima.2018.01.099.
4. Summary and conclusion In this paper, the single particle transient response and displacement damages in CISs induced by the neutron irradiation at Back-n in CSNS facility have been investigated. The increase of dark signal and DSNU, and the occurrences of dark signal spikes due to the stable bulk defects in the SCR induced by neutron displacement damage are analyzed. The two-level and multi-level RTS behaviors induced by neutron displacement radiation are related to the point defects and cluster defects located in the SCR. The typical characterizations of the single particle transient 71
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
[8] Z.J. Wang, S.Y. Huang, M.B. Liu, Z.G. Xiao, B.P. He, Z.B. Yao, J.K. Sheng, AIP Adv. 4 (2014) 077108. [9] C. Virmontois, V. Goiffon, F. Corbiere, P. Magnan, S. Girard, A. Bardoux, IEEE Trans. Nucl. Sci. 59 (2012) 2872. [10] C. Durnez, V. Goiffon, C. Virmontois, J.M. belloir, P. Magnan, L. Rubaldo, IEEE Trans. Nucl. Sci. 64 (2017) 19.
[11] G.R. Hopkinson, IEEE Trans. Nucl. Sci. 47 (2000) 2480. [12] C. Virmontois, V. Goiffon, P. Magnan, O. Saint-pe, S. Girard, S. Petit, G. Rolland, A. Bardoux, IEEE Trans. Nucl. Sci. 58 (2011) 3085. [13] E. Martin, T. Nuns, C. Virmontois, J.P. David, O. Gilard, IEEE Trans. Nucl. Sci. 60 (2013) 2503.
72
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Single particle transient response and displacement damage in CMOS image sensors induced by high energy neutrons at Back-n in CSNS facility Zujun Wang a,b ,∗, Yuanyuan Xue a , Wei Chen a ,∗, Hao Ning b , Rui Xu b , Xiaoqiang Guo a , Jiangkun Sheng a , Zhibin Yao a , Baoping He a , Wuying Ma a , Guantao Dong a a b
State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an, China School of Materials Science and Engineering, Xiangtan University, Hunan, China
ARTICLE
INFO
Keywords: Spallation neutron source CMOS image sensor (CIS) Single particle transient response Displacement damage Neutron radiation
ABSTRACT Neutron radiation experiments of the complementary metal-oxide semiconductor (CMOS) image sensors (CISs) at back-streaming white neutrons (Back-n) in China Spallation Neutron Source (CSNS) facility are presented. The displacement damages induced by neutron radiation are characterized by the analysis of the increase of dark signal and dark signal non-uniformity, and the occurrences of dark signal spike and random telegraph signal (RTS). The two-level and multi-level RTS behaviors induced by neutron displacement radiation are presented. The mechanisms of the dark signal spikes and RTS induced by neutron displacement radiation are analyzed respectively. The single particle transient response characterizations are described by analyzing the online dark images during neutron radiation. The mechanisms of the dark signal spikes and the white lines induced by the single transient neutron events are also demonstrated by analyzing the interactions between the higher energy neutrons and bulk silicon lattices of CISs.
1. Introduction China Spallation Neutron Source (CSNS) facility provides a large scientific platform. The back-streaming white neutrons (Back-n) from a spallation target through the proton beam line in CSNS facility has a very wide neutron energy spectrum [1], which can be used to perform neutron radiation. Radiation effects in a complementary metal-oxide semiconductor (CMOS) image sensor (CIS) induced by gamma rays, X rays, protons, and neutrons have been widely investigated for their applications in space radiation or nuclear radiation environments [2– 5]. However, the investigations are mainly focused on the total ionizing dose damage and the displacement damage, and fewer studies have focused on the single particle transient response and displacement damage in CISs induced by high energy neutrons. No literatures have reported the above researches at Back-n in CSNS facility. The primary goal of this paper is to present the radiation experiments of the CISs at Back-n in CSNS. First, we introduce the experimental setup and the sample. Second, we investigate the neutron displacement damages by the analysis of the increase of dark signal and dark signal non-uniformity (DSNU), and the occurrences of dark signal spike and random telegraph signal (RTS). Third, we describe the single particle transient response characterizations and the mechanisms of the
occurrences of dark signal spikes and white lines induced by the single transient neutron events. 2. Experimental details The neutron radiation experiments were carried out at Back-n in CSNS facility (Dongguan, China). The schematic layout of the Back-n in CSNS facility [6] is shown in Fig. 1 and the neutron radiation position is located at endstation2 (ES#2, 80 m). The photo of the experimental setup at Back-n in CSNS facility is shown in Fig. 2. The neutron energy spectrum at Back-n in CSNS facility ranges from 1eV to 200 MeV and the detailed spectrum of Back-n beamline is shown in [7]. The neutron flux at the exposure position (ES#2) is about 1.4 × 106 n/(cm2 s) in these radiation experiments. The online tests were carried out to observe the single particle transient response during radiation. The offline tests were carried out to investigate the displacement damage. The neutron fluences of the off-line tests include 1.12 × 1010 , 1.69 × 1010 , 2.80 × 1010 , and 3.36 × 1010 n/cm2 . All the tests were performed at room temperature about 25 ◦ C. The CIS type used in these experiments is a Sony IMX249. The image size is diagonal 13.4 mm (type 1/1.2). The unit cell size is
∗ Corresponding author at: State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an, China. E-mail addresses: [email protected] (Z. Wang), [email protected] (W. Chen).
https://doi.org/10.1016/j.nima.2018.12.033 Received 11 October 2018; Received in revised form 24 November 2018; Accepted 9 December 2018 Available online 25 December 2018 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 1. Schematic layout of Back-n in CSNS facility [6].
5.86 μm × 5.86 μm. The resolution is 1920 × 1200. The ADC output is 12 bits. The readout method is the global shutter which can scan all pixel signals at once. The max frame rate is 30 frame/s. 3. Results and discussion 3.1. Displacement damage induced by neutrons Neutron radiation mainly induces displacement damage by elastic and inelastic interactions between the neutron beam and the bulk silicon lattices of a CIS. The total ionizing dose (cumulative ionizing) damage induced by neutron radiation in a CIS is very small and can be negligible. The typical characterizations of displacement damage in a CIS are presented by the analysis of the increase of dark signal and DSNU, and the occurrences of dark signal spikes and RTS. Dark signal spikes represent the individual pixels with dark signal level obviously higher than the ordinary pixels in irradiated or unirradiated pixel regions. Fig. 3 shows the dark signal spikes increase with increasing neutron radiation fluence. The occurrences of dark signal spikes are mainly due to stable bulk defects in the space charge region (SCR) of a CIS induced by neutron displacement damage. The unit of dark signal is DN (digital number). Fig. 4 shows the histograms of dark signal distributions versus neutron radiation fluence. From the dark signal distributions as shown in Fig. 4, we can observe that the
Fig. 2. The experimental setup at Back-n in CSNS facility.
number and amplitude of dark signal spikes increase with increasing neutron radiation fluence. However, the noticeable impacts on the dark
Fig. 3. The dark signal spikes increase with increasing neutron radiation fluence.
69
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Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 4. Histograms of dark signal distributions versus neutron radiation fluence.
Fig. 6. Typical two-level RTS in a CIS induced by neutron radiation.
Fig. 5. The dark signal and DSNU versus neutron radiation fluence.
Fig. 7. Typical multi-level RTS in a CIS induced by neutron radiation.
signals are not shown in all the pixels in the CIS. Neutron radiation impacts a part of the pixels because the interactions between the neutron beams and the bulk silicon lattices have very small cross section. These interactions create bulk defects in silicon of a CIS and subsequently induce the increase of dark signal and the occurrences of dark signal spikes [5]. The occurrences of dark signal spikes result in the increase of dark signal and DSNU of a CIS. DSNU is the non-uniformity of a dark image, which originates from the different output charge signals from one pixel to another in the solid state image sensors [2,8]. Fig. 5 shows the dark signal and DSNU versus neutron radiation fluence. The increase of dark signal is due to the Shockley–Read–Hall (SRH) generation in the SCR induced by the stable bulk defects [9]. The increase of DSNU is due to the occurrences of dark signal spikes and RTS induced by neuron displacement damage, which increases the non-uniformity of dark signals. RTS is a phenomenon that the dark signal switches randomly between two or more discrete states [10]. RTS in a CIS represents the dark signal fluctuation with time in the pixels. This phenomenon can be observed as pixel blinking in a series of dark images, which will influence the calibration of a CIS by impacting the noise performance. Protoninduced RTS has been reported in the literatures [11–13], however little previous work [10] has focused on neutron-induced RTS in a CIS. Fig. 6 shows the typical two-level RTS in a CIS induced by neutron radiation at Back-n in CSNS. The mean values and the standard variations of dark signals in the selected pixels are also presented. Fig. 7 shows the typical multi-level RTS of a CIS induced by neutron radiation at Back-n in CSNS. From Figs. 6 and 7, the RTS behaviors in the different pixels
of a CIS show the obvious differences because the displacement damage in the pixels is various. Highly degraded pixels exhibit large transition amplitudes as shown in Figs. 6 and 7. Before radiation, the RTS behavior in a CIS is very small. After neutron radiation, the RTS behavior in a CIS shows two-level or multilevel RTS. Bulk defects such as point defects and cluster defects induced by neutron radiation are mainly located in the SCR of a CIS. These bulk defects with energy level within the bandgap behave as classical SRH generation–recombination mechanism, which induces dark signal fluctuation with time in the pixels. We speculate that point defects capture charge and then release it with time in the pixels, which usually induces the signal output to switch between two discrete levels. Cluster defects can form several SRH generation–recombination centers, which may induce the signal output to switch between several discrete levels. Thus, the two-level RTS behaviors may be mainly due to point defects induced by neutron radiation. However, the multi-level RTS behaviors may be mainly due to cluster defects induced by neutron radiation. 3.2. Single particle transient response induced by neutrons The single particle transient responses induced by neutrons at Backn in CSNS are observed during radiation. The typical characterizations exhibit occurrences of dark signal spikes (not persistent) and bright lines. These responses are not permanent and disappear after radiation immediately. The responses are also randomly distributed in the dark images during radiation. The subimages of 100 × 100 pixels are extracted from the dark images of 1920 × 1200 to investigate the single particle transient responses. Fig. 8 shows the typical transient responses 70
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
Fig. 8. The typical transient responses induced by neutron events: sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams with the elimination of the dark signal induced by displacement damage: (a) shape 1, (b) shape 2, (c) shape 3, (d) shape 4.
Fig. 9. Sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams at continuous frames with the same radiation states: (a) before radiation, (b) 01th frame, (c) 02th frame, (d) after radiation.
response are the occurrences of dark signal spikes (not persistent) and bright lines during neutron radiation. The dark signal spikes and the bright lines originate from the transient ionizing charges collected in a single pixel or several adjacent pixels. Both the dark signal spikes and the bright lines are not persistent and the characterizations of the bright lines depend on the transient ionizing of transport traces of the secondary particles. More experiments irradiated by high energy protons and neutrons will be carried out in the future to further investigate the single particle transient response and displacement damages in CISs.
induced by neutron events. Sets of subimages (inversion of black and white color) captured from a CIS exposed to the neutron beams with the elimination of the dark signal induced by displacement damage exhibit the different shape of the bright lines. Fig. 9 shows the sets of dark subimages (inversion of black and white color) of a CIS exposed to the neutron beams at continuous frames with the same radiation states: (a) before radiation, (b) 01th frame, (c) 02th frame, (d) after radiation. Before radiation, there is no dark signal spikes and bright lines. However, a large number of the dark signal spikes and the bright lines appear during radiation as shown in Figs. 9(b) and 9(c). After radiation, there are still many dark signal spikes as shown in Fig. 9(d), which is due to the displacement damage. In contrast to the dark signal spikes of single particle transient responses, these dark signal spikes always exist and have fixed position. The experiments show that the higher energy neutrons at Backn in CSNS will induce the transient neutron events during radiation. The interactions between the higher energy neutrons and the bulk silicon lattices of a CIS induce the secondary particles which can ionize electron–hole pairs in the transport trace during radiation. The transient neutron events may exist in a single pixel or several adjacent pixels. The transient ionizing charges collected in a single pixel result in a dark signal spike. The transient ionizing charges collected in several adjacent pixels result in a bright line. Both the dark signal spikes and the bright lines are not persistent and depend on the transient ionizing of transport traces of the secondary particles. Fig. 9 shows the single particle transient responses are also randomly distributed.
Acknowledgments This work was supported by the National Science Foundation of China (Grant No. 11875223, 11805155, 11690043), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA15015000), the Innovation Foundation of Radiation Application, China (Grant No. KFZC2018040201), and the Foundation of State Key Laboratory of China (Grant No. SKLIPR1803, 1610). The authors gratefully acknowledge all members of CSNS-WNS for their earnest support and help during the work. References [1] H.T. Jing, J.Y. Tang, H.Q. Tang, H.H. Xia, T.J. Liang, Z.Y. Zhou, Q.P. Zhong, X.C. Ruan, Nucl. Instrum. Methods A 621 (2010) 91. [2] Z.J. Wang, W.Y. Ma, J. Liu, Y.Y. Xue, B.P. He, Z.B. Yao, S.Y. Huang, M.B. Liu, J.K. Sheng, Nucl. Instrum. Methods A 820 (2016) 89. [3] D. Doering, M. Deveaux, M. Domachowski, C. Dritsa, I. Froehlich, M. Koziel, C. Muentz, S. Ottersbach, F. M.Wagner, J. Stroth. Nucl. Instrum. Methods A 658 (2011) 133. [4] V. Goiffon, P. Magnan, O. Saint-Pe, F. Bernard, G. Rolland, Nucl. Instrum. Methods A 610 (2009) 225. [5] C. Virmontois, V. Goiffon, P. Magnan, S. Girard, O. Saint-pe, S. Petit, G. Rolland, A. Bardoux, IEEE Trans. Nucl. Sci. 59 (2012) 927. [6] Z.X. Tan, J.Y. Tang, H.T. Jing, R.R. Fan, Q. Li, C.J. Ning, J. Bao, X.C. Ruan, G. q.Luan, C.Q. Feng, X.P. Zhang, Nucl. Instrum. Methods A 889 (2018) 122. [7] Z. Tan, J. Tang, H. Jing, R. Fan, Q. Li, C. Ning, J. Bao, X. Ruan, G. Luan, C. Feng, X. Zhang, Energy-resolved fast neutron resonance radiography at CSNS, Nucl. Instrum. Methods A (2018) http://dx.doi.org/10.1016/j.nima.2018.01.099.
4. Summary and conclusion In this paper, the single particle transient response and displacement damages in CISs induced by the neutron irradiation at Back-n in CSNS facility have been investigated. The increase of dark signal and DSNU, and the occurrences of dark signal spikes due to the stable bulk defects in the SCR induced by neutron displacement damage are analyzed. The two-level and multi-level RTS behaviors induced by neutron displacement radiation are related to the point defects and cluster defects located in the SCR. The typical characterizations of the single particle transient 71
Z. Wang, Y. Xue, W. Chen et al.
Nuclear Inst. and Methods in Physics Research, A 920 (2019) 68–72
[8] Z.J. Wang, S.Y. Huang, M.B. Liu, Z.G. Xiao, B.P. He, Z.B. Yao, J.K. Sheng, AIP Adv. 4 (2014) 077108. [9] C. Virmontois, V. Goiffon, F. Corbiere, P. Magnan, S. Girard, A. Bardoux, IEEE Trans. Nucl. Sci. 59 (2012) 2872. [10] C. Durnez, V. Goiffon, C. Virmontois, J.M. belloir, P. Magnan, L. Rubaldo, IEEE Trans. Nucl. Sci. 64 (2017) 19.
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