Characterization of CIAE developed double-sided silicon strip detector for charged particles

Characterization of CIAE developed double-sided silicon strip detector for charged particles 1 2 corresp first-author xinxing@hku.hk xinxing@hku.hk xinxing@hku.hk 2 1 3 corresp cjlin@ciae.ac.cn cjlin@ciae.ac.cn cjlin@ciae.ac.cn 2 corresp jleehc@hku.hk jleehc@hku.hk jleehc@hku.hk 1 1 4 1 4 1 2 2 2 2 1 1 1 1 2 2 2 1 China Institute of Atomic Energy, Beijing 102413, China China Institute of Atomic Energy, Beijing 102413, China Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China College of Physics and Technology, Guangxi Normal University, Guilin 541004, China College of Physics and Technology, Guangxi Normal University, Guilin 541004, China Beijing Kelixing Photoelectric Technology Co., Ltd., Beijing 102413, China Beijing Kelixing Photoelectric Technology Co., Ltd., Beijing 102413, China A double-sided silicon strip detector (DSSD) with active area of 48 mm×48 mm and thickness of 300 μM has been developed. Each side of DSSD consists of 48 strips, each with width of 0.9 mm and inter-strip separation of 0.1 mm. Electrical properties and detection performances including full depletion bias voltage, reverse leakage current, rise time, energy resolution and crosstalk have been studied. At a bias of 80 V, leakage current in each strip is less than 15 nA, and rise time for alpha particle at 5157 keV is approximately 15 ns on both sides. Good energy resolutions have been achieved with 0.65% - 0.80% for the junction strips and 0.85% - 1.00% for the ohmic strips. The crosstalk is found to be negligible on both sides. The overall good performance of DSSD indicates its readiness for various nuclear physics experiments. Double-sided silicon strip detector P-stop Detection performance Crosstalk 1 Introduction 1 Development of silicon detectors has been receiving benefits from the rapid technological advancement of the integrated circuit (IC) since the 1970s, when the earliest attempts to introduce planar process to the fabrication of silicon detectors took place [ 1 1 - 4 4 1-4 ]. Techniques like oxide passivation, ion implantation and photolithography have successfully resolved the key issues encountered prior to the planar technology, granting feasibility to the fabrication of silicon strip detectors (SSD). The advantages of an SSD include precise positioning, high energy resolution, long range of linear response, rapid response time and its feasibility to be fabricated into various designated shape, facilitating its applicability in many research areas. Since the beginning of the 21st century, many detector arrays composed of SSD like CD [ 5 5 ], DRAGON [ 6 6 ], HiRA [ 7 7 ], LEDA [ 8 8 ], MUST [ 9 9 ] and MUST2 [ 10 10 ] have been constructed to meet individual experimental objectives. In China, several institutions such as the China Institute of Atomic Energy (CIAE), the Beijing Kelixing Photoelectric Technology Co., Ltd. and the Institute of Modern Physics, Chinese Academy of Science (IMP) have begun the development of double-sided silicon strip detectors (DSSD). Prior to this project, CIAE had successfully developed the single-sided silicon strip detectors (SSSD) that have been used in many nuclear experiments [ 11 11 - 14 14 11-14 ] for about a decade. A more recent development by CIAE in the quadrant-silicon detectors (QSD) [ 15 15 ] has also been shown successful in providing a new detector technology to various nuclear experiments [ 16 16 - 18 18 16-18 ]. In this article, a cooperative production of DSSD by CIAE and the Beijing Kelixing Photoelectric Technology will be introduced, and performance test conducted at the University of Hong Kong will be presented. 2 Detection principle 1 The DSSD being developed in this work has an active area of 48 mm × 48 mm and a thickness of 300 μM. The P+ doped junction side and the N+ doped ohmic side comprise the basic framework of PN-junction. At each side, all the 48 strips are evenly distributed and mutually parallel, each with a strip width of 0.9 mm and an inter-strip distance of 0.1 mm( Fig. 1 Fig. 1 ). At an adequate supply of bias voltage around 60 V, the depletion region will expand and occupy the entire Si wafer. When charged particle penetrates into the active region, electron-hole pairs will be produced. Due to the presence of electric field, electrons will be drifted towards the ohmic side, while the holes will be drifted towards the junction side. Electrical pulses at the electrodes are then being generated due to the induction caused by the motions of these charges. Positive signal pulses and negative signal pulses will be received by the junction side and the ohmic side, respectively, with energy loss information of the particle being encoded in the pulses. Each silicon strip could be treated as an individual detector during the signal collection. 3 Manufacturing procedure 1 The entire manufacturing procedure of the DSSD takes place inside a cleanroom. An N-type 4-inch silicon wafer of 300 μM in thickness and 10 kΩ in resistivity is used for fabrication. After polishing and cleaning, the Si wafer undergoes the following manufacturing procedure: a. Oxide passivation: The Si wafer is being exposed under high-temperature environment, with O 2 gas stream flowing past its surface so that an oxide layer SiO 2 of 600 nm thick is formed on top of it. b. Photolithography: With the use of photolithographic equipment and proper etching techniques, some segments of the oxide layer are removed to form pattern of inter-strips on both sides. c. Ion implantation: Junction side is doped with boron ions, forming a P+ region; ohmic side is doped with phosphorus ions, forming an N+ region. At both sides, the thickness of doping is around 400 nm. This step creates the P+-Intrinsic-N+ (PIN) diode structure for the detector. In order to improve isolation on the ohmic side, P-stop technique has been employed to isolate the N+ strips, i.e. boron ions have been doped into the N+ inter-strip region and its surrounding to form P+ isolation implants. d. Thermal annealing: The doped Si wafer is being exposed under dry nitrogen gas at 600 ℃ for 30 min. e. Al metalization and patterning: A thin layer of Al is being sputtered onto both sides, and those which fall on top of the oxide layer are then being removed. f. Alloy and encapsulation: Each individual strip is being separated and encapsulated before the detector chip is mounted onto the printed circuit board (PCB). The mounting employs ultrasonic soldering to establish permanent connection between the readout contacts on the PCB and the Al electrodes of DSSD which have been alloyed at 380 ℃. All these procedures follow the fabrication parameters which have been optimized beforehand based on simulations or previous experience. One noteworthy issue is the tendency for N+ strips to accumulate charges, which can easily introduce electrical breakdown across inter-strip region. Hence, P-stop technique has been implemented in this work to enhance strip isolation. A schematic figure that illustrates the important structural features of DSSD is given in Fig. 2 Fig. 2 . 4 Characterization 1 A schematic diagram for the readout electronics is shown in Fig. 3 Fig. 3 . Each junction strip is supplied with a negative bias from the Mesytec MHV-4 via a preamplifier of internal resistance 100 MΩ, while each ohmic strip is connected to ground through an 100 MΩ resistor. Self-developed integrated charge sensitive preamplifiers SPA02 (bandwidth of 275 MHz and signal-to-noise ratio of 5 <math id="M1"><mrow><mtext>nV/</mtext><msqrt><mrow><mtext>Hz</mtext></mrow></msqrt></mrow></math> ) have been used to perform current-to-volage conversion and linear amplification on the signals collected from the strips on both sides. All preamplified signals are then be sent to the Mesytec MSCF-16 amplifier for further amplification and Gaussian shaping, with shaping times of 1 μs and 2 μs both being tested. After the MSCF-16 amplifier, energy signals from both sides are being sent to V785 ADC before being recorded by the computer, while time signals from the two sides are being processed differently. Two time signals, ECL timing and trigger output (NIM), have been extracted from MSCF-16 that connects the junction strips. The ECL timing is sent toward V775 TDC as start signal, while the trigger output is sent to trigger the ADC after consecutively undergoing an octal constant-fraction discriminator CF8000, and an octal gate and delay generator GG8010, in which an output is taken to serve as the common stop. For the ohmic side, only the ECL time signal is extracted and sent to the TDC as start signal. In this test, both energy signal and time signals are acquired by the RIBFDAQ system [ 19 19 ]. To investigate the performance of DSSD, alpha response is chosen to be studied by locating a triple alpha source that consists of 239 Pu, 241 Am and 244 Cm at approximately 3.0 cm away from the detector. Throughout the test, the entire piece of DSSD as well as the preamplifiers are all placed within a vacuum chamber with an air pressure of 10 -3 Pa. 4.1 Voltage amplitude, rise time and leakage current 2 Voltage amplitude and rise time of pre-amplified signals have been measured as functions of bias voltage using an oscilloscope. When increasing bias voltage from 0 V to 80 V, both signal amplitude and rise time turn saturated after 60 V (see Fig. 4 Fig. 4 ). At full depletion, body capacitance of each strip to the opposite side is around 50 pF. In practice, a bias higher than the saturation voltage could be taken, provided that the bias does not exceed breakdown voltage. Throughout the test, a bias of 80 V has been adopted and the total leakage currents for all strips was found to be less than 720 nA, that is, each strip has less than 15 nA on average ( Fig. 5 Fig. 5 ). 4.2 Energy resolution of a single strip 2 A triple alpha source containing 239 Pu, 241 Am and 244 Cm has been used. Their primary peak energies are given by 5157 keV, 5486 keV and 5805 keV, respectively. Energy calibration has been performed for each strip individually prior to analysis. Using linear calibration, E ( x ) = mx + c , where x is the channel number, we find that m fluctuates less than 5% in all strips, while c shifts less than 1% of the full energy range ( 10000 keV ). Energy spectra collected by the 24th junction strip and the 24th ohmic strip have been given in Fig. 6 Fig. 6 for illustration. Limited by the energy resolution of detector, a low-energy tail is formed from the superposition of primary peak with non-primary peaks - take 239 Pu for example, the major alpha decay paths include 5157 keV (71%), 5144 keV (17%) and 5106 keV (12%). At a bias of 80 V, the energy resolutions of all strips are found to fluctuate within 0.65% - 0.80% for the junction strips and 0.85% - 1.00% for the ohmic strips, while the electronic noise is found to contribute around 0.20% to the resolution [ 20 20 ]. 4.3 Absence of crosstalk between adjacent strips 2 Geometry of the strips inevitably introduces unwanted coupled capacitance. When an incoming charged particle hits a particular strip, charges are being accumulated in it, causing induced charges to arise in its adjacent strips due to the presence of inter-strip capacitance [ 9 9 , 21 21 ]. Being referred as crosstalk in the literature [ 22 22 , 23 23 ], this effect introduces pseudo-signal in the electronics at low energy region, even though it has no apparent effect on the energy resolution of alpha signal. The significance of crosstalk depends on inter-strip capacitance C i and body capacitance of the strip to the opposite side C b . Significance of crosstalk is associated with the ratio C i / C b , so it is desirable to have it as small as possible. Nevertheless, increasing C b leads to weakening of signal amplitude, hence elimination of crosstalk was approached by minimizing C i . For our detector, C b ≈50 pF and C i is small enough to reject crosstalk between adjacent strips, as will be discussed in the next paragraph. Ideally during the absence of crosstalk, only the incidences that have successfully penetrated through the inter-strip SiO 2 layer and injected into the active region will generate coincidence signals at adjacent strips. When plotted as a two-dimensional spectrum, these events are expected to have their energies shared by the adjacent strips, where the energy distribution is linearly related to the proximity of electron-hole pair creation point to the strip edge. This provides us a way to check the absence of crosstalk by plotting the coincidence events between the adjacent strips. As illustrated in Fig. 7 Fig. 7 , the expected energy distribution is observed for adjacent ohmic strips when particles enter from the junction side, indicating the absence of crosstalk on the ohmic side; if crosstalk had indeed occured, clusters besides from those three belts of alpha signals would have shown up. Absence of crosstalk on the junction side has also been confirmed by a similar manner. In our previous development, elimination of crosstalk could only be achieved on the junction side but not on the ohmic side [ 24 24 ]. In this test, such issue has been overcome as P+ isolation implants have successfully been implemented to the ohmic strips. 4.4 Pixel 2 The primary objective of developing DSSD is to acquire two-dimensional spatial position information of the charged particles with the pixels resulted from the intersection of strips on both sides. In this development, 48 strips have been equipped on each side, yielding a total of 48 × 48 = 2304 pixels on the detector. The two-dimensional energy spectra of pixels have been investigated as illustrated in Fig. 8 Fig. 8 , where the clusters of events correspond to the alpha peaks in Fig. 6 Fig. 6 . 5 Summary 1 In summary, a DSSD with 48 strips on each side has been developed and performance test has been conducted at a bias voltage of 80 V. Each strip carries a leakage current of around 15 nA. When alpha particles of 5157 keV enter from the junction side, rise time of signal after preamplifiers is about 15 ns on both sides. Energy resolutions are good, with the junction sides ranging within 0.65% - 0.80% and the ohmic sides ranging within 0.85% - 1.00%. Crosstalk is found to be insignificant on both sides. The detectability of pixels has been demonstrated. Overall, the results indicate that the DSSD being developed is ready to be used in nuclear physics experiments. In the future, we plan to develop DSSD of different thicknesses as well as of different shapes to best meet the goals of various experiments. At the same time, we also wish to improve the success rate of production. References G. Keil , E. Lindner , Low-noise oxide passivated p+n silicon detectors , Nucl. Instrum. Methods 101 ( 1972 ) 43 - 46 . doi: 10.1016/0029-554X(72)90753-7 http://doi.org/10.1016/0029-554X(72)90753-7 Low-noise oxide passivated p+n silicon detectors G. Keil , E. Lindner , Low-noise silicon planar detectors for room temperature application , Nucl. Instrum. Methods 104 ( 1972 ) 209 - 214 . doi: 10.1016/0029-554X(72)90319-9 http://doi.org/10.1016/0029-554X(72)90319-9 Low-noise silicon planar detectors for room temperature application J. Kemmer , Fabrication of low noise silicon radiation detectors by the planar process , Nucl. Instrum. Methods 169 ( 1980 ) 499 - 502 . doi: 10.1016/0029-554X(80)90948-9 http://doi.org/10.1016/0029-554X(80)90948-9 Fabrication of low noise silicon radiation detectors by the planar process J. Kemmer , Improvement of detector fabrication by the planar process , Nucl. Instrum. Meth. A 226 ( 1984 ) 89 - 93 . doi: 10.1016/0168-9002(84)90173-6 http://doi.org/10.1016/0168-9002(84)90173-6 Improvement of detector fabrication by the planar process A. Ostrowski , S. Cherubini , T. Davinson et al ., CD: A double sided silicon strip detector for radioactive nuclear beam experiments , Nucl. Instrum. Meth. A 480 ( 2002 ) 448 - 455 . doi: 10.1016/S0168-9002(01)00954-8 http://doi.org/10.1016/S0168-9002(01)00954-8 CD: A double sided silicon strip detector for radioactive nuclear beam experiments D. Hutcheon , S. Bishop , L. Buchmann et al , The DRAGON facility for nuclear astrophysics at TRIUMF-ISAC: design, construction and operation , Nucl. Instrum. Meth. A 498 ( 2003 ) 190 - 210 . doi: 10.1016/S0168-9002(02)01990-3 http://doi.org/10.1016/S0168-9002(02)01990-3 The DRAGON facility for nuclear astrophysics at TRIUMF-ISAC: design, construction and operation M. Wallace , M. Famiano , M.-J. van Goethem et al , The high resolution array (HiRA) for rare isotope beam experiments , Nucl. Instrum. Meth. A 583 ( 2007 ) 302 - 312 . doi: 10.1016/j.nima.2007.08.248 http://doi.org/10.1016/j.nima.2007.08.248 The high resolution array (HiRA) for rare isotope beam experiments T. Davinson , W. Bradfield-Smith , S. Cherubini et al , Louvainedinburgh detector array (LEDA): a silicon detector array for use with radioactive nuclear beams , Nucl. Instrum. Meth. A 454 ( 2000 ) 350 - 358 . doi: 10.1016/S0168-9002(00)00479-4 http://doi.org/10.1016/S0168-9002(00)00479-4 Louvainedinburgh detector array (LEDA): a silicon detector array for use with radioactive nuclear beams Y. Blumenfeld , F. Auger , J. Sauvestre et al , MUST: A silicon strip detector array for radioactive beam experiments , Nucl. Instrum. Meth. A 421 ( 1999 ) 471 - 491 . doi: 10.1016/S0168-9002(98)01178-4 http://doi.org/10.1016/S0168-9002(98)01178-4 MUST: A silicon strip detector array for radioactive beam experiments E. Pollacco , E. Atkin , F. Auger et al , MUST II: Large solid angle light charged particle telescope for inverse kinematics studies with radioactive beams , AIP Conference Proceedings 680 ( 2003 ) 313 - 316 . doi: 10.1063/1.1619724 http://doi.org/10.1063/1.1619724 MUST II: Large solid angle light charged particle telescope for inverse kinematics studies with radioactive beams C.J. Lin , X.X. Xu , H.M. Jia et al , Experimental study of two-proton correlated emission from 29S excited states , Phys. Rev. C 80 ( 2009 ) 014310 . doi: 10.1103/PhysRevC.80.014310 http://doi.org/10.1103/PhysRevC.80.014310 Experimental study of two-proton correlated emission from 29S excited states X.X. Xu , C.J. Lin , H.M. Jia et al , Investigation of two-proton emission from excited states of the odd-Z nucleus 28P by complete-kinematics measurements , Phys. Rev. C 81 ( 2010 ) 054317 . doi: 10.1103/PhysRevC.81.054317 http://doi.org/10.1103/PhysRevC.81.054317 Investigation of two-proton emission from excited states of the odd-Z nucleus 28P by complete-kinematics measurements X.X. Xu , C.J. Lin , H.M. Jia et al , Observation of two-α emission from high-lying excited states of 18 Ne by completekinematics measurements , Phys. Rev. C 82 ( 2010 ) 064316 . doi: 10.1103/PhysRevC.82.064316 http://doi.org/10.1103/PhysRevC.82.064316 Observation of two-α emission from high-lying excited states of 18 Ne by completekinematics measurements X.X. Xu , C.J. Lin , H.M. Jia et al , Correlations of two protons emitted from excited states of 28S and 27P , Phys. Let. B 727 ( 2013 ) 126 - 129 . doi: 10.1016/j.physletb.2013.10.029 http://doi.org/10.1016/j.physletb.2013.10.029 Correlations of two protons emitted from excited states of 28S and 27P P.F. Bao , C.J. Lin , F. Yang et al , Development of large-area quadrant silicon detector for charged particles , Chinese Phy. C 38 ( 12 ) ( 2014 ) 126001 . doi: 10.1088/1674-1137/38/12/126001 http://doi.org/10.1088/1674-1137/38/12/126001 Development of large-area quadrant silicon detector for charged particles L.J. Sun , X.X. Xu , C.J. Lin et al , A detection system for charged-particle decay studies with a continuous-implantation method , Nucl. Instrum. Meth. A 804 ( 2015 ) 1 - 7 . doi: 10.1016/j.nima.2015.09.039 http://doi.org/10.1016/j.nima.2015.09.039 A detection system for charged-particle decay studies with a continuous-implantation method L.J. Sun , X.X. Xu , D.Q. Fang et al , β-decay study of the Tz=-2 proton-rich nucleus 20Mg , Phys. Rev. C 95 ( 2017 ) 014314 . doi: 10.1103/PhysRevC.95.014314 http://doi.org/10.1103/PhysRevC.95.014314 β-decay study of the Tz=-2 proton-rich nucleus 20Mg X.X. Xu , C.J. Lin , L.J. Sun et al , Observation of β-delayed two-proton emission in the decay of 22 Si , Phys. Let. B 766 ( 2017 ) 312 - 316 . doi: 10.1016/j.physletb.2017.01.028 http://doi.org/10.1016/j.physletb.2017.01.028 Observation of β-delayed two-proton emission in the decay of 22 Si H. Baba , T. Ichihara , T. Ohnishi et al , New data acquisition system for the RIKEN radioactive isotope beam factory, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers , Detectors and Associated Equipment 616 ( 1 ) ( 2010 ) 65 - 68 . doi: 10.1016/j.nima.2010.02.120 http://doi.org/10.1016/j.nima.2010.02.120 New data acquisition system for the RIKEN radioactive isotope beam factory, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers J.A. Duenas , G. Pasquali , L. Acosta et al , Characterization of an NTD Double-Sided Silicon Strip Detector Employing a Pulsed Proton Microbeam , IEEE Trans. Nucl. Sci ., 64 ( 9 ) ( 2017 ) 2551 - 2560 doi: 10.1109/TNS.2017.2734568 http://doi.org/10.1109/TNS.2017.2734568 Characterization of an NTD Double-Sided Silicon Strip Detector Employing a Pulsed Proton Microbeam J. Yorkston , A.C. Shotter , D.B. Syme et al , Nucl. Instrum. Meth. A , 262 ( 1987 ) 353 - 358 . doi: 10.1016/0168-9002(87)90873-4 http://doi.org/10.1016/0168-9002(87)90873-4 Nucl. Instrum. Meth. A B. Bruyneel , P. Reiter , A. Wiens et al , Crosstalk properties of 36-fold segmented symmetric hexagonal HPGe detectors , Nucl. Instrum. Meth. A , 599 ( 2-3 ) ( 2009 ) 196 - 280 . doi: 10.1016/j.nima.2008.11.011 http://doi.org/10.1016/j.nima.2008.11.011 Crosstalk properties of 36-fold segmented symmetric hexagonal HPGe detectors J.E. Lamport , G.M. Mason , M.A. Perkins et al , Nucl. Instrum. Methods , 134 ( 1 ) ( 1976 ) 71 - 76 . doi: 10.1016/0029-554X(76)90125-7 http://doi.org/10.1016/0029-554X(76)90125-7 Nucl. Instrum. Methods L.J. Sun , C.J. Lin , F. Yang et al , Development and test of double-sided silicon strip detector , Atomic Energy Science and Technology 49 ( 2 ) ( 2015 ) 336 - 342 , (in Chinese) . doi: 10.7538/yzk.2015.49.02.0336 http://doi.org/10.7538/yzk.2015.49.02.0336 Development and test of double-sided silicon strip detector 10.1007/s41365-018-0406-0 This work was supported by the National Natural Science Foundation of China (No. U1432246, U1632136, U1432127, 11375268, 11635015,and 11475263) and the National Basic Research Program of China (No. 2013CB834404). 2017-10-23 2018-03-05 2018-03-06 2018-04-03 2018-05-01 2021-04-11 © China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, ChineseNuclear Society and Springer Nature Singapore Pte Ltd. 2018 This is a post-peer-review, pre-copyedit version of an article published in Nuclear Science and Techniques. The final authenticated version is available online at: http://dx.doi.org/10.1007/s41365-018-0406-0 http://dx.doi.org/10.1007/s41365-018-0406-0 . 2018 Nuclear Science and Techniques 05 29