002868985 001__ 2868985
002868985 005__ 20240318135013.0
002868985 0248_ $$aoai:cds.cern.ch:2868985$$pcerncds:FULLTEXT$$pcerncds:CERN:FULLTEXT$$pcerncds:CERN
002868985 0247_ $$2DOI$$9Springer$$a10.1140/epjc/s10052-024-12601-3
002868985 037__ $$9arXiv$$aarXiv:2308.13231$$cphysics.ins-det
002868985 035__ $$9arXiv$$aoai:arXiv.org:2308.13231
002868985 035__ $$9Inspire$$aoai:inspirehep.net:2691041$$d2024-03-14T05:28:27Z$$h2024-03-15T03:27:48Z$$mmarcxml$$ttrue$$uhttps://inspirehep.net/api/oai2d
002868985 035__ $$9Inspire$$a2691041
002868985 041__ $$aeng
002868985 100__ $$avan Rijnbach, Milou$$jORCID:0000-0003-3728-5102$$mmilou.van.rijnbach@cern.ch$$tGRID:grid.9132.9$$tGRID:grid.5510.1$$uCERN$$uOslo U.$$vCERN, Geneva, Switzerland$$vUniversity of Oslo, Oslo, Norway
002868985 245__ $$9Springer$$aRadiation hardness of MALTA2 monolithic CMOS imaging sensors on Czochralski substrates
002868985 246__ $$9arXiv$$aRadiation Hardness of MALTA2 Monolithic CMOS Sensors on Czochralski Substrates
002868985 269__ $$c2023-08-25
002868985 260__ $$c2024-03-10
002868985 300__ $$a16 p
002868985 520__ $$9Springer$$aMALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS sensor imaging technology. In order to comply with the requirements of high energy physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce random telegraph signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3 $\times $ 10$^{15}$ 1 MeV $\mathrm {n_{eq}/{cm}^2}$ with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021 to 2023 using the MALTA telescope.
002868985 520__ $$9arXiv$$aMALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS technology. In order to comply with the requirements of High Energy Physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce Random Telegraph Signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3E15 1 MeV neq/cm2 with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021-2023 using the MALTA telescope.
002868985 540__ $$3preprint$$aarXiv nonexclusive-distrib 1.0$$uhttp://arxiv.org/licenses/nonexclusive-distrib/1.0/
002868985 540__ $$3publication$$aCC-BY-4.0$$bSpringer$$fSCOAP3$$uhttp://creativecommons.org/licenses/by/4.0/
002868985 542__ $$3publication$$dThe Author(s)$$g2024
002868985 65017 $$2arXiv$$ahep-ex
002868985 65017 $$2SzGeCERN$$aParticle Physics - Experiment
002868985 65017 $$2arXiv$$aphysics.ins-det
002868985 65017 $$2SzGeCERN$$aDetectors and Experimental Techniques
002868985 690C_ $$aCERN
002868985 690C_ $$aARTICLE
002868985 700__ $$aBerlea, Dumitru Vlad$$tGRID:grid.7683.a$$uDESY, Zeuthen$$vDESY, Zeuthen, Germany
002868985 700__ $$aDao, Valerio$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aGaži, Martin$$tGRID:grid.4991.5$$uOxford U.$$vUniversity of Oxford, Oxford, UK
002868985 700__ $$aAllport, Phil$$tGRID:grid.6572.6$$uBirmingham U.$$vUniversity of Birmingham, Birmingham, UK
002868985 700__ $$aAsensi Tortajada, Ignacio$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aBehera, Prafulla$$tGRID:grid.417969.4$$uIndian Inst. Tech., Madras$$vIndian Institute of Technology Madras, Chennai, India
002868985 700__ $$aBortoletto, Daniela$$tGRID:grid.4991.5$$uOxford U.$$vUniversity of Oxford, Oxford, UK
002868985 700__ $$aButtar, Craig$$tGRID:grid.8756.c$$uGlasgow U.$$vUniversity of Glasgow, Glasgow, UK
002868985 700__ $$aDachs, Florian$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aDash, Ganapati$$tGRID:grid.417969.4$$uIndian Inst. Tech., Madras$$vIndian Institute of Technology Madras, Chennai, India
002868985 700__ $$aDobrijević, Dominik$$tGRID:grid.9132.9$$tGRID:grid.4808.4$$uCERN$$uZagreb U.$$vCERN, Geneva, Switzerland$$vUniversity of Zagreb, Zagreb, Croatia
002868985 700__ $$aFasselt, Lucian$$tGRID:grid.7683.a$$uDESY, Zeuthen$$vDESY, Zeuthen, Germany
002868985 700__ $$ade Acedo, Leyre Flores Sanz$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aGabrielli, Andrea$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aGonella, Laura$$tGRID:grid.6572.6$$vUniversity of Birmingham, Birmingham, UK
002868985 700__ $$aGonzález, Vicente$$tGRID:grid.5338.d$$uValencia U.$$vUniversitat de València, Valencia, Spain
002868985 700__ $$aGustavino, Giuliano$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aJana, Pranati$$tGRID:grid.417969.4$$uIndian Inst. Tech., Madras$$vIndian Institute of Technology Madras, Chennai, India
002868985 700__ $$aLi, Long$$tGRID:grid.6572.6$$vUniversity of Birmingham, Birmingham, UK
002868985 700__ $$aPernegger, Heinz$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aPiro, Francesco$$tGRID:grid.9132.9$$vCERN, Geneva, Switzerland
002868985 700__ $$aRiedler, Petra$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aSandaker, Heidi$$tGRID:grid.5510.1$$uOslo U.$$vUniversity of Oslo, Oslo, Norway
002868985 700__ $$aSolans Sánchez, Carlos$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aSnoeys, Walter$$tGRID:grid.9132.9$$uCERN$$vCERN, Geneva, Switzerland
002868985 700__ $$aSuligoj, Tomislav$$tGRID:grid.4808.4$$uZagreb U.$$vUniversity of Zagreb, Zagreb, Croatia
002868985 700__ $$aNúñez, Marcos Vázquez$$tGRID:grid.9132.9$$tGRID:grid.5338.d$$uCERN$$uValencia U.$$vCERN, Geneva, Switzerland$$vUniversitat de València, Valencia, Spain
002868985 700__ $$aVijay, Anusree$$tGRID:grid.417969.4$$uIndian Inst. Tech., Madras$$vIndian Institute of Technology Madras, Chennai, India
002868985 700__ $$aWeick, Julian$$tGRID:grid.9132.9$$tGRID:grid.6546.1$$uCERN$$uDarmstadt, Tech. U.$$vCERN, Geneva, Switzerland$$vTechnische Universität Darmstadt, Darmstadt, Germany
002868985 700__ $$aWorm, Steven$$tGRID:grid.7683.a$$uDESY, Zeuthen$$vDESY, Zeuthen, Germany
002868985 700__ $$aZoubir, Abdelhak M.$$tGRID:grid.6546.1$$uDarmstadt, Tech. U.$$vTechnische Universität Darmstadt, Darmstadt, Germany
002868985 773__ $$c251$$n3$$pEur. Phys. J. C$$v84$$y2024
002868985 8564_ $$82473111$$s16971$$uhttp://cds.cern.ch/record/2868985/files/Clsize_thr_final.png$$y00011 Average efficiency (top left) and cluster size (top right) as a function of threshold. The bottom images show their respective 2D map at an operating threshold corresponding to 150 e$^-$. Results are shown for a non-irradiated MALTA2 sample (Cz, NGAP, 300 \textmu m thick, high doping of n$^-$ layer) at -6 V.
002868985 8564_ $$82473112$$s15568$$uhttp://cds.cern.ch/record/2868985/files/Pos_Delay_IrradLevels.png$$y00030 Relative shift of the mean time of arrival of the leading hit within cluster with respect to the scintillator reference, as a function of the distance of the associated telescope track from the pixel centre. Results are shown for four MALTA2 samples (Cz, XDPW, high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to four different irradiation levels (non-irradiated, 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ ) and are operated at best operating threshold, corresponding to 250, 240, 250, and 120 e$^-$, at -6, -30, -50, -55V bias voltage, respectively. The operating threshold point for each sample is selected to minimise the RMS of its timing distribution. The leading hit time data are sorted into 1.82$\times$1.82 \textmu m$^2$ bins based on their associated track position within the pixel. The quoted mean corresponds to the Gaussian fit to the core of the distribution for each bin along the diagonal of the pixel.
002868985 8564_ $$82473113$$s51871$$uhttp://cds.cern.ch/record/2868985/files/Plot_1D_thr_VH_dope_new.png$$y00003 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473114$$s262687$$uhttp://cds.cern.ch/record/2868985/files/Noise2D_W18R19.png$$y00008 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473115$$s21586$$uhttp://cds.cern.ch/record/2868985/files/vsubs_operationalRegion_W18R21.png$$y00020 Average efficiency (in black) and noise occupancy (in red) as a function of threshold in electrons of a MALTA2 sample (Cz, XDPW, very high doping n$^-$ layer, 100 \textmu m, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ . The substrate voltage is set at -20, -35, -50 V. The number of masked pixels is below about 0.02\% of the entire chip in the several configurations.
002868985 8564_ $$82473116$$s14102$$uhttp://cds.cern.ch/record/2868985/files/Pos_Delay_3E15.png$$y00032 Relative shift of the mean time of arrival of the leading hit within a cluster with respect to a scintillator reference, as a function of the distance of the associated telescope track from the pixel centre. Results are shown for two MALTA2 samples (Cz, XDPW, 100 \textmu m thick, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and operated at -55V. The samples differ in the doping level of the n$^-$ layer, i.e. high and very high, and the results are shown for best performing operational threshold, corresponding to 120 and 110 e$^-$, respectively. The operating threshold point for both samples is selected to minimise the RMS of its timing distribution.
002868985 8564_ $$82473117$$s4778040$$uhttp://cds.cern.ch/record/2868985/files/2308.13231.pdf$$yFulltext
002868985 8564_ $$82473118$$s15349$$uhttp://cds.cern.ch/record/2868985/files/SUB_clustersize_IrradLevels.png$$y00016 Average cluster size versus bias voltage for three MALTA2 samples (XDPW, high doping n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and the results are shown at best performing operating threshold, corresponding to 240, 260, and 120 e$^-$, respectively.
002868985 8564_ $$82473119$$s70551$$uhttp://cds.cern.ch/record/2868985/files/XDPW.drawio.png$$y00002 Cross sections of the process modifications of the Tower Semiconductor 180 nm CMOS imaging technology. Top image shows the standard modified process (STD) where an n$^-$ layer is introduced on top of the p-type substrate. Bottom left image shows the process modification where a gap in the low dose n$^-$ layer is introduced (NGAP). The bottom right image shows the process modification with an extra deep p-well located under the deep p-well (XDPW). Images are not drawn to scale and are adapted from Ref.\cite{munker2019simulations}.
002868985 8564_ $$82473120$$s17710$$uhttp://cds.cern.ch/record/2868985/files/time_ALL.png$$y00023 Left image shows time of arrival of the leading hit in the cluster with respect to a scintillator reference. The quoted $\sigma_t = 1.7$~ns corresponds to the Gaussian fit to the core of the distribution. Right image shows in-time efficiency. Black curve corresponds to in-time efficiency within a 25 ns window, blue curve corresponds to a 15 ns windows, and the green and magenta cure represent a 10 and 8 ns window, respectively. Red line represents maximum achievable efficiency without timing constraints. Both measurements are performed on a MALTA2 sample (Cz, XDPW, very high doping n$^-$ layer, 100 \textmu m thick) at -6 V. Threshold corresponds to 170 e$^-$.
002868985 8564_ $$82473121$$s38153$$uhttp://cds.cern.ch/record/2868985/files/time_eff.png$$y00024 Left image shows time of arrival of the leading hit in the cluster with respect to a scintillator reference. The quoted $\sigma_t = 1.7$~ns corresponds to the Gaussian fit to the core of the distribution. Right image shows in-time efficiency. Black curve corresponds to in-time efficiency within a 25 ns window, blue curve corresponds to a 15 ns windows, and the green and magenta cure represent a 10 and 8 ns window, respectively. Red line represents maximum achievable efficiency without timing constraints. Both measurements are performed on a MALTA2 sample (Cz, XDPW, very high doping n$^-$ layer, 100 \textmu m thick) at -6 V. Threshold corresponds to 170 e$^-$.
002868985 8564_ $$82473122$$s28178$$uhttp://cds.cern.ch/record/2868985/files/inpixel_matchedCl_Time_mu_W12R7__IDB120_ITHR025_SUB30.0_PWELL06_deg00.0.png$$y00027 Projection of the variation of the mean timing of the leading hit within a cluster with respect to a scintillator reference for four MALTA2 samples (Cz, XDPW, high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to four different irradiation levels (non-irradiated, 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ ) and are operated at best operating threshold, corresponding to 250, 240, 250, and 120 e$^-$, at -6, -30, -50, -55V bias voltage, respectively. The leading hit time data are sorted into 1.82$\times$1.82 \textmu m$^2$ bins based on their associated track position within the pixel extracted from the telescope data. Hits from over the entire chip are projected onto a 2$\times$2 pixel matrix. The quoted mean time value is extracted from a Gaussian fit to the core of the timing distribution for each bin relative to the bin with the smallest value. The operating conditions of the four samples correspond to the data point where the timing RMS is minimised, while the efficiency lies above 90\%.
002868985 8564_ $$82473123$$s61089$$uhttp://cds.cern.ch/record/2868985/files/NGAP.drawio.png$$y00001 Cross sections of the process modifications of the Tower Semiconductor 180 nm CMOS imaging technology. Top image shows the standard modified process (STD) where an n$^-$ layer is introduced on top of the p-type substrate. Bottom left image shows the process modification where a gap in the low dose n$^-$ layer is introduced (NGAP). The bottom right image shows the process modification with an extra deep p-well located under the deep p-well (XDPW). Images are not drawn to scale and are adapted from Ref.\cite{munker2019simulations}.
002868985 8564_ $$82473124$$s15297$$uhttp://cds.cern.ch/record/2868985/files/SUB_efficiency_IrradLevels.png$$y00014 Average efficiency versus bias voltage for three MALTA2 samples (XDPW, high doping n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and the results are shown at best performing operating threshold, corresponding to 240, 260, and 120 e$^-$, respectively.
002868985 8564_ $$82473125$$s48779$$uhttp://cds.cern.ch/record/2868985/files/Eff_2D_final.png$$y00012 Average efficiency (top left) and cluster size (top right) as a function of threshold. The bottom images show their respective 2D map at an operating threshold corresponding to 150 e$^-$. Results are shown for a non-irradiated MALTA2 sample (Cz, NGAP, 300 \textmu m thick, high doping of n$^-$ layer) at -6 V.
002868985 8564_ $$82473126$$s51820$$uhttp://cds.cern.ch/record/2868985/files/InPix_Eff_2D_TOT_run__W18R21__IDB120_ITHR015_SUB55.0_PWELL06.png$$y00019 In-pixel efficiency projected over a 2$\times$2 pixel matrix for two MALTA2 samples (Cz, XDPW, 100 \textmu m thick, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and operated at $-55$ V. The samples differ in the doping level of the n$^-$ layer, i.e. high (left) and very high (right), and the results are shown for best performing operational threshold, corresponding to 120 and 110 e$^-$, respectively. Note the difference in Z-axis scale.
002868985 8564_ $$82473127$$s28692$$uhttp://cds.cern.ch/record/2868985/files/inpixel_matchedCl_Time_mu_W18R21__IDB120_ITHR015_SUB55.0_PWELL06.png$$y00031 Projection of the variation of the mean timing of the leading hit within a cluster with respect to a scintillator reference, for a MALTA2 sample (Cz, XDPW, very high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and operated at $-55$ V. The operating threshold corresponds to $\sim$110 e$^-$.
002868985 8564_ $$82473128$$s13777$$uhttp://cds.cern.ch/record/2868985/files/SUB_efficiency_IrradLevels_3E15.png$$y00017 Average efficiency versus bias voltage for two MALTA2 samples (Cz, XDPW, 100 \textmu m thick, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ . The samples differ in the doping level of the n$^-$ layer, i.e. high and very high, and the results are shown for best performing operational threshold, corresponding to 120 and 110 e$^-$, respectively.
002868985 8564_ $$82473129$$s30508$$uhttp://cds.cern.ch/record/2868985/files/inpixel_matchedCl_Time_mu_W12R19__IDB120_ITHR020_SUB55.0_PWELL06_deg00.0.png$$y00029 Projection of the variation of the mean timing of the leading hit within a cluster with respect to a scintillator reference for four MALTA2 samples (Cz, XDPW, high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to four different irradiation levels (non-irradiated, 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ ) and are operated at best operating threshold, corresponding to 250, 240, 250, and 120 e$^-$, at -6, -30, -50, -55V bias voltage, respectively. The leading hit time data are sorted into 1.82$\times$1.82 \textmu m$^2$ bins based on their associated track position within the pixel extracted from the telescope data. Hits from over the entire chip are projected onto a 2$\times$2 pixel matrix. The quoted mean time value is extracted from a Gaussian fit to the core of the timing distribution for each bin relative to the bin with the smallest value. The operating conditions of the four samples correspond to the data point where the timing RMS is minimised, while the efficiency lies above 90\%.
002868985 8564_ $$82473130$$s32650$$uhttp://cds.cern.ch/record/2868985/files/Eff_2D_run__W12R7__IDB120_ITHR025_SUB15.0_PWELL06_deg00.0.png$$y00015 2D Efficiency map of the entire matrix of a MALTA2 sample (Cz, XDPW, 100 \textmu m thick, high doping of n$^-$ layer and backside metallisation) irradiated to 1$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and operated at $-15$ V. The average efficiency is 99\% and the operating threshold corresponds to 240 e$^-$.
002868985 8564_ $$82473131$$s27075$$uhttp://cds.cern.ch/record/2868985/files/inpixel_matchedCl_Time_mu_W12R0__IDB120_ITHR020_SUB06.0_PWELL06.png$$y00026 Projection of the variation of the mean timing of the leading hit within a cluster with respect to a scintillator reference for four MALTA2 samples (Cz, XDPW, high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to four different irradiation levels (non-irradiated, 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ ) and are operated at best operating threshold, corresponding to 250, 240, 250, and 120 e$^-$, at -6, -30, -50, -55V bias voltage, respectively. The leading hit time data are sorted into 1.82$\times$1.82 \textmu m$^2$ bins based on their associated track position within the pixel extracted from the telescope data. Hits from over the entire chip are projected onto a 2$\times$2 pixel matrix. The quoted mean time value is extracted from a Gaussian fit to the core of the timing distribution for each bin relative to the bin with the smallest value. The operating conditions of the four samples correspond to the data point where the timing RMS is minimised, while the efficiency lies above 90\%.
002868985 8564_ $$82473132$$s383880$$uhttp://cds.cern.ch/record/2868985/files/sample_backside_FIB_102.png$$y00009 Cross-sectional SEM image of a MALTA2 sample with backside metallisation. The light grey area indicates the 1 \textmu m thick Aluminium layer.
002868985 8564_ $$82473133$$s264626$$uhttp://cds.cern.ch/record/2868985/files/Noise2D_W14R12.png$$y00006 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473134$$s224579$$uhttp://cds.cern.ch/record/2868985/files/Thres2D_W18R19.png$$y00007 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473135$$s212872$$uhttp://cds.cern.ch/record/2868985/files/Thres2D_W14R12.png$$y00005 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473136$$s51211$$uhttp://cds.cern.ch/record/2868985/files/Eff_Inpix_3E15_Hdop.png$$y00018 In-pixel efficiency projected over a 2$\times$2 pixel matrix for two MALTA2 samples (Cz, XDPW, 100 \textmu m thick, and backside metallisation) irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and operated at $-55$ V. The samples differ in the doping level of the n$^-$ layer, i.e. high (left) and very high (right), and the results are shown for best performing operational threshold, corresponding to 120 and 110 e$^-$, respectively. Note the difference in Z-axis scale.
002868985 8564_ $$82473137$$s17495$$uhttp://cds.cern.ch/record/2868985/files/Eff_thr_final.png$$y00010 Average efficiency (top left) and cluster size (top right) as a function of threshold. The bottom images show their respective 2D map at an operating threshold corresponding to 150 e$^-$. Results are shown for a non-irradiated MALTA2 sample (Cz, NGAP, 300 \textmu m thick, high doping of n$^-$ layer) at -6 V.
002868985 8564_ $$82473138$$s47929$$uhttp://cds.cern.ch/record/2868985/files/ClSize_2D_final.png$$y00013 Average efficiency (top left) and cluster size (top right) as a function of threshold. The bottom images show their respective 2D map at an operating threshold corresponding to 150 e$^-$. Results are shown for a non-irradiated MALTA2 sample (Cz, NGAP, 300 \textmu m thick, high doping of n$^-$ layer) at -6 V.
002868985 8564_ $$82473139$$s60463$$uhttp://cds.cern.ch/record/2868985/files/STD.drawio.png$$y00000 Cross sections of the process modifications of the Tower Semiconductor 180 nm CMOS imaging technology. Top image shows the standard modified process (STD) where an n$^-$ layer is introduced on top of the p-type substrate. Bottom left image shows the process modification where a gap in the low dose n$^-$ layer is introduced (NGAP). The bottom right image shows the process modification with an extra deep p-well located under the deep p-well (XDPW). Images are not drawn to scale and are adapted from Ref.\cite{munker2019simulations}.
002868985 8564_ $$82473140$$s14738$$uhttp://cds.cern.ch/record/2868985/files/SUB_RMS_IrradLevels.png$$y00025 RMS of timing difference distribution versus bias voltage. Only data points where the detection efficiency lies above 85\% are taken into account. Shown here are four MALTA2 samples (XDPW, 100 \textmu m thick, and backside metallisation). Three samples feature the high doping of the n$^-$ layer. They are irradiated to 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and the results are shown at best performing operating threshold, corresponding to 240, 260, and 120 e$^-$, respectively. One sample features the very high doping of the n$^-$ layer. It is irradiated to 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ and the results are shown at best performing operating threshold, corresponding to 110 e$^-$.
002868985 8564_ $$82473141$$s20018$$uhttp://cds.cern.ch/record/2868985/files/Plot_1D_noise_VH_dope_new.png$$y00004 Threshold distribution (top left image) and noise distribution (top right image), of non-irradiated MALTA2 (Cz, 100 \textmu m) NGAP, high doping of n$^-$ layer (in red) and XDPW, very high doping (in black) at -6 V SUB bias. Threshold corresponds to $\sim$180 e$^-$. The cut-off for the noise distribution at 2 e$^-$ is correlated to the granularity of the noise scan. Additionally the corresponding 2D distribution for the entire matrix of the high doping sample are shown (middle images) and for the very high doping sample (bottom images).
002868985 8564_ $$82473142$$s13606$$uhttp://cds.cern.ch/record/2868985/files/Time_1D_Y.png$$y00021 Time of arrival of leading hit in the cluster with respect to a scintillator reference along the column (left image) and row direction (right image) of the pixel matrix. A correction in the Y-direction is applied due to the time propagation across the column which exhibits a linear behaviour. A correction in the X-direction is applied due to the non-uniformities in the chip response. Error bars represent the corresponding RMS. Both measurements are performed on a MALTA2 sample (Cz, XDPW, very high doping n$^-$ layer, 100 \textmu m thick) at -6 V. Threshold corresponds to 170 e$^-$.
002868985 8564_ $$82473143$$s12115$$uhttp://cds.cern.ch/record/2868985/files/Time_1D_X.png$$y00022 Time of arrival of leading hit in the cluster with respect to a scintillator reference along the column (left image) and row direction (right image) of the pixel matrix. A correction in the Y-direction is applied due to the time propagation across the column which exhibits a linear behaviour. A correction in the X-direction is applied due to the non-uniformities in the chip response. Error bars represent the corresponding RMS. Both measurements are performed on a MALTA2 sample (Cz, XDPW, very high doping n$^-$ layer, 100 \textmu m thick) at -6 V. Threshold corresponds to 170 e$^-$.
002868985 8564_ $$82473144$$s29341$$uhttp://cds.cern.ch/record/2868985/files/inpixel_matchedCl_Time_mu_W12R10__IDB120_ITHR035_SUB50.0_PWELL06_deg00.0.png$$y00028 Projection of the variation of the mean timing of the leading hit within a cluster with respect to a scintillator reference for four MALTA2 samples (Cz, XDPW, high doping of n$^-$ layer, 100 \textmu m thick, and backside metallisation). The samples are irradiated to four different irradiation levels (non-irradiated, 1, 2, and 3$\times$10$^{15}$ 1 MeV $\mathrm{n_{eq}/{cm}^2}$ ) and are operated at best operating threshold, corresponding to 250, 240, 250, and 120 e$^-$, at -6, -30, -50, -55V bias voltage, respectively. The leading hit time data are sorted into 1.82$\times$1.82 \textmu m$^2$ bins based on their associated track position within the pixel extracted from the telescope data. Hits from over the entire chip are projected onto a 2$\times$2 pixel matrix. The quoted mean time value is extracted from a Gaussian fit to the core of the timing distribution for each bin relative to the bin with the smallest value. The operating conditions of the four samples correspond to the data point where the timing RMS is minimised, while the efficiency lies above 90\%.
002868985 8564_ $$82518312$$s2560420$$uhttp://cds.cern.ch/record/2868985/files/document.pdf$$yFulltext
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