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Superconducting Nanowire Single-Photon Detectors K. K. Berggren Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 111114-rochester [email protected] 1 http://messenger.jhuapl.edu/news_room 111114-rochester Free-Space Optical Communications transmitter 109 km receiver Boroson, Biswas, Edwards, "Overview of NASA's mars laser communications demonstration system," FREE-SPACE LASER COMM. TECH. XVI 5338: 1628, 2004 Toyoshima, et. al., “Comparison of microwave and light wave communication systems in space applications,” Opt. Eng. 46 015003 (2007) 3 111114-rochester Free-Space Optical Communications transmitter 109 km receiver Boroson, Biswas, Edwards, "Overview of NASA's mars laser communications demonstration system," FREE-SPACE LASER COMM. TECH. XVI 5338: 1628, 2004 Toyoshima, et. al., “Comparison of microwave and light wave communication systems in space applications,” Opt. Eng. 46 015003 (2007) hv hv time 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000 1111 1110 1101 1100 1011 1010 1001 1000 0111 0110 0101 0100 0011 0010 0001 0000 Encodes 01011001 (4 bits/photon) 4 111114-rochester Photons • Illumination in eye from 1 pixel of laptop at 100 km in 1 sec • Energy inversely proportional to wavelength – Longer wavelength => harder to detect 5 111114-rochester Berggren Superconductive Nanowire Superconductive Nanowire Single-Photon Detector Single-Photon Detector 3 µm electrode 90 nm electrode Yang et al., IEEE TAS (2005) 111114-rochester Gol’tsman et al., APL, (2001). proximity-effectcorrection features 6 Eye Anatomy cornea lens vitreous humor retina optic nerve 111114-rochester 7 Eye Anatomy cornea light lens antireflection coating sapphire substrate vitreous humor NbN cavity mirror niobium nitride sapphire retina gold…. 111114-rochester contact pad optic nerve 8 Tapetum Lucidum of a Cat retina ~ 100 nm tapetum lucidum Bernstein and Pease, “Electron Microscopy of the Tapetum Lucidum of the Cat” Journal of Cell Biology, Vol. 5, 35-39, (1959) 111114-rochester 9 Berggren Eye Anatomy cornea light lens antireflection coating sapphire substrate vitreous humor NbN cavity mirror niobium nitride retina sapphire tapetum lucidum gold…. 111114-rochester contact pad optic nerve 10 Characteristics of Photon Detectors • Efficiency incident photons with no signal hν voltage time • Reset time incident photons blocked by earlier signal time varying delay between photons and signals • Jitter time t1 • Dark count rate t2 t3 voltage pulses with no corresponding photon time 111114-rochester 11 Nanowire Single-Photon Detector 1 / jitter [MHz] 104 APPLICATIONS superconducting nanowire single-photon detector • VLSI device evaluation avalanche photodiode photomultiplier tube • LIDAR transition edge sensor • Communication 1 / reset time [MHz] device efficiency [%] 104 100 Comparison at 1.55 µm 111114-rochester – quantum – interplanetary Device Operation DEVICE OPERATION 111114-rochester Superconductive Nanowire Behavior I critical current, Ic superconducting 111114-rochester V Berggren Detection Mechanism Explanation superconductor is biased near its transition 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester Detection Mechanism Explanation photon-induced hotspot forces bias current above critical density 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 351, pp. 349–356, 2001. Detection Mechanism Explanation resistive barrier spans nanowire 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester Detection Mechanism Explanation resistance grows from heating 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester Detection Mechanism Explanation current is diverted 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester Detection Mechanism Explanation superconductivity is restored 4 nm niobium nitride < 100 nm Ibias detector Rload L 111114-rochester Detection Mechanism Explanation superconductivity is restored 4 nm niobium nitride < 100 nm Ibias detector Rload L 21 111114-rochester 111114-rochester 22 Detection Mechanism Explanation bias current is restored 4 nm niobium nitride < 100 nm Ibias detector Rload L Kerman, Dauler, Keicher,Yang, KB, Gol'tsman,Voronov, Applied Physics Letters, (2006) 111114-rochester SNSPD integrated in an optical cavity NbN gold Au mirror ~λ/4 sapphire cavity dielectric anti-reflection coating 90 nm NbN fiber sapphire Cross-section transmission-electron micrograph 111114-rochester Rosfjord et al., Opt. Express (2006) 24 Summary of Device Performance Counts Normalized (a.u.) (a.u.) Normalized Counts 1 ps, 1550 nm optical pulse Voltage (mV) 3 ns Time (ns) 1 28.5 ps FWHM 0.1 0.01 Kerman et al. in APL (2006) -100 -80 -60 -40 -20 0 20 40 60 80 Time (ps) Time (ps) Background Counts ~100 s-1 (97.5% bias, 2.7K) Detection efficiency ~ 70 % 0.8 ~ 65 % 0.4 0 0 111114-rochester 0.5 bias current / Ic 70-nm-wide detector, 140-nm pitch 210-nm-thick cavity 1 Collaboration with Lincoln Laboratory 25 Fabrication FABRICATION 111114-rochester Basic Fabrication Flow hydrogen silsesquioxane (HSQ) (electron-beam resist) gold contact pads niobium nitride (from collaborators) sapphire substrate 111114-rochester Basic Fabrication Flow hydrogen silsesquioxane (HSQ) (electron-beam resist) gold contact pads niobium nitride (from collaborators) sapphire substrate niobium nitride nanowire 111114-rochester Basic Fabrication Flow hydrogen silsesquioxane (HSQ) (electron-beam resist) gold contact pads niobium nitride (from collaborators) sapphire substrate niobium nitride nanowire HSQ anti-reflection coating 111114-rochester 29 Cavity Fabrication Flow HSQ Au contact pads NbN detector 1nm/ 120nm Ti/Au mirror sapphire substrate HSQ cavity HSQ ARC 30 111114-rochester Photon Statistics APPLICATION 111114-rochester 31 10 µm 111114-rochester 32 Pseudo-Thermal Source Setup Ground Glass 12 V DC Fan (up to 6000 rpm) Grating-Stabilized CW Diode Laser 1070 nm Time-stamp each channel ~7 ns bins Scattered Light Speckle Fiber 4-element SNSPD Cryostat 111114-rochester 6-channel FPGA PC 33 Element 4 Element 3 Element 2 Element 1 3-photon coincidences t t1 t2 2-photon coincidence conditions: 10 µm t1 = 0 t2 = 0 t1 = t2 3-photon coincidence : t1 = t2 = 0 111114-rochester 34 3rd-order Intensity Correlations g(3)(0,0) = 5.87 ~ 3! “High-order temporal coherences of chaotic and laser light”, Stevens, Baek, Dauler, Kerman, Molnar, Hamilton, Berggren, Mirin, and Nam, Optics Express, 18, 1430 (2010) 35 111114-rochester Photon Statistics NANO-ANTENNAE 111114-rochester The Three Keys to Efficiency coupling efficiency resistive state formation absorptance threshold detection v v active area t × r × × × v × 37 111114-rochester Antenna – Integrated Detector top view large pitch small pitch fill the gap with gold cross section v 111114-rochester v t v t t Optical Nano-Antenna … … Au NbN k TM 111114-rochester 39 Final Version Optical Nano-Antenna … Au … NbN k TM 111114-rochester 40 Fabrication SiO2/ Ti/Au Au pad Au pad 9 mm fabrication challenges • e-beam writing on thick HSQ • gold migration in evaporation ion-beam cross-section Pt Au 80 nm 600 nm 111114-rochester Au sapphire HSQ Nano-Optical Antenna for Nanowire Detectors • Nano-antennae improve collection, permitting 3 x area, with same reset time • 600-nm pitch, 9-mm-by9-mm area • 47% device efficiency • 5 ns reset time Hu et. al. Optics Express, 2010 111114-rochester Photon Statistics SUB-30-NM DEVICES 111114-rochester 43 60 nm 40 nm 30 nm 20 nm 10 nm 80 nm 44 60 nm 40 nm 30 nm 20 nm 10 nm 80 nm 45 60 nm 40 nm 30 nm 20 nm 10 nm 80 nm 46 30-nm-wide-nanowire SNSPD 1 µm 30 nm 111114-rochester 47 Standard vs Ultranarrow-Nanowire SNSPDs Constrictions w = 90 nm 48 111114-rochester Standard vs Ultranarrow-Nanowire SNSPDs Constrictions constriction-free constricted more constricted w = 90 nm 49 111114-rochester Standard vs Ultranarrow-Nanowire SNSPDs Constrictions w = 30 nm constriction-free constricted more constricted w = 90 nm 50 111114-rochester Standard vs Ultranarrow-Nanowire SNSPDs Constrictions w = 30 nm constriction-free constricted more constricted w = 90 nm 111114-rochester A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 51 351, pp. 349–356, 2001. Standard vs Ultranarrow-Nanowire SNSPDs Constrictions w = 30 nm constriction-free constricted more constricted w = 90 nm 111114-rochester A. D. Semenov, G. N. Gol’tsman, and A. A. Korneev, “Quantum detection by current carrying superconducting film,” Physica C, vol. 52 351, pp. 349–356, 2001. Standard vs Ultranarrow-Nanowire SNSPDs Constrictions w = 30 nm constriction-free constricted constriction-free constricted more constricted w = 90 nm 53 111114-rochester Standard vs Ultranarrow-Nanowire SNSPDs Negligible responsivity above 2 μm w = 90 nm w = 55 nm w = 100 nm 111114-rochester Gol’tsman et al., IEEE Trans. Appl. Supercond (2011) 54 Standard vs Ultranarrow-Nanowire SNSPDs Negligible responsivity above 2 μm w = 90 nm w = 55 nm w = 100 nm 111114-rochester Gol’tsman et al., IEEE Trans. Appl. Supercond (2011) 55 Detection efficiency vs IB and wavelength w = 85 nm λ = 0.5 μm λ = 2 μm 56 111114-rochester Detection efficiency vs IB and wavelength w = 30 nm λ = 0.5 μm λ = 2 μm 57 111114-rochester Detection efficiency vs IB, wavelength and width η (%) 0 3.6 w = 85 nm 7.2 w = 50 nm w = 30 nm 58 111114-rochester Fabrication SIGNAL TO NOISE RATIO 111114-rochester 59 Low signal to noise ratio 60 111114-rochester Low signal to noise ratio 61 111114-rochester “A Cascade Switching Superconducting Single Photon Detector,” M. Ejrnaes, R. Cristiano, O. Quaranta, S. Pagano, A. Gaggero, F. Mattioli, R. Leoni, B. Voronov, and G. Gol'tsman, Appl. Phys. Lett. 91, 262509 (2007) 111114-rochester 62 Superconducting Nanowire Avalanche Photodetectors (SNAPs) 63 111114-rochester Superconducting Nanowire Avalanche Photodetectors (SNAPs) 30 nm 1.4 µm 111114-rochester 64 Basic model of SNAP operation + VOUT - RA IB LS 111114-rochester 65 Basic model of SNAP operation + VOUT - RA IB LS 111114-rochester 66 Basic model of SNAP operation + VOUT - RA IB LS 111114-rochester 67 Basic model of SNAP operation + VOUT - RA IB LS 111114-rochester 68 SNAPs improve the SNR 4-SNAP 3-SNAP 2-SNAP SNSPD 69 111114-rochester Experimental results 2-SNAP SNSPD λ = 1550 nm 70 111114-rochester Experimental results threshold current 2-SNAP SNSPD λ = 1550 nm 71 111114-rochester Experimental results 3-SNAP 2-SNAP SNSPD λ = 1550 nm 72 111114-rochester Experimental results 3-SNAP 2-SNAP SNSPD λ = 1550 nm In which bias range are 3-SNAPs working as single-photon detectors? 73 111114-rochester SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 74 SNAP operation below the avalanche current arm + VOUT - RA IB LS 111114-rochester 75 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 76 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 77 SNAP operation below the avalanche current trigger + VOUT - RA IB LS 111114-rochester 78 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 79 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 80 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 81 SNAP operation below the avalanche current + VOUT - RA IB LS 111114-rochester 82 Experimental results threshold current 3-SNAP 2-SNAP SNSPD λ = 1550 nm arm-trigger avalanche 83 111114-rochester η Power Dependence Explained increasing power IAV 111114-rochester 84 η Power Dependence Explained photon arm + dark count trigger IAV photon arm + photon trigger 85 111114-rochester Electro-thermal simulation of SNAPs secondary initiating Iout s initiating: n normal / superconducting boundary s secondary: photon avalanche 111114-rochester n J.Yang et al. IEEE TAS (2007) F. Marsili et al., APL (2011) superconducting 86 3-SNAP in “arm-trigger” regime arm trigger Pseudo 2-SNAP I3 I2 I1 Iout superconducting 87 111114-rochester Inter-arrival time measurements Avalanche mode: voltage hν time 111114-rochester 88 Inter-arrival time measurements Avalanche mode: voltage hν tD1 τΦ1 tD2 τΦ2 tD3 τΦ3 f tD t ft t 111114-rochester tD4 τΦ4 time 89 Inter-arrival time measurements Arm-trigger mode: voltage T A T A T time 111114-rochester 90 Inter-arrival time measurements Arm-trigger mode: voltage T A tD1 t2Φ1 T A tD2 t2Φ2 f tD t ft 2 t 111114-rochester T time 91 Inter-arrival time histograms IB > IAV IB < IAV F. Marsili et al., Nanolett. (2011) 111114-rochester 92 20-nm-wide-nanowire SNAPs 1.1 µm 20 nm 111114-rochester 93 20-nm-nanowire-width SNAPs 4-SNAP 3-SNAP 2-SNAP λ = 1550 nm 111114-rochester 94 The Future • Scaling sensitivity out to longer wavelengths – (is high-efficiency single-photon detection possible at 10 um?) • Understanding the source of jitter – Intrinsic to material? Electronic? Thermal? Electrothermal? – Dependent on design/architecture? Engineerable? • Can we break the 1 ns speed limit? – Need to investigate new materials – Need to investigate new device designs • Is near-100% efficiency possible? 111114-rochester 95 1.1 µm 10 nm 111114-rochester 96 Acknowledgements MIT Quantum Nanostructures and Nanofabrication Group Vikas Anant (now at PhotonSpot) Francesco Bellei Andrew Dane Eric Dauler (Lincoln Lab Fellow, now at Lincoln Laboratory) Charles Herder (undergraduate) Xiaolong Hu (now at U. of Michigan) Hasan Korre Francesco Marsilli (post-doc, now at NIST) Faraz Najafi Kristen Sunter Joel Yang (ASTAR Fellowship, now at A*STAR) 111114-rochester MIT Lincoln Laboratory Eric Dauler Andrew J. Kerman Richard Molnar Bryan Robinson Scott Hamilton NIST Martin J. Stevens Burm Baek Sae Woo Nam Richard P. Mirin Other Collaborators M. Csete (U. of Szeged) Boris Voronov (MSPU) Gregory Gol’tsman (MSPU) Sponsors AFOSR, IARPA, DARPA, NASA, NSF Photon Statistics END OF PRESENTATION 111114-rochester 98
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