Plasma-enhanced atomic layer deposition of superconducting niobium nitride

Sowa, Mark J.; Yemane, Yonas; Zhang, Jinsong; Palmstrom, Johanna C.; Ju, Ling; Strandwitz, Nicholas C.; Prinz, Fritz B.; Provine, J.

doi:10.1116/1.4972858

Cited by 23 publications

(29 citation statements)

References 41 publications

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“…The inset also shows that our films follow a universal relation observed for thin superconducting films [29] linking T c , film thickness t, and sheet resistance R : we find that our results are similar to NbN deposited with other methods [29,31]. For thicker films, T c appears to saturate at 13.8-13.9 K which is comparable to other materials studies [29,30,32], while decreasing to 8.7 K for the thinnest film (t=7 nm), which can be attributed to disorder enhanced Coulomb repulsions [35,36]. We also find that the superconducting transition width increases significantly for the thinner films, which can in turn be attributed to disorder broadened density of states [36] or reduced vortexantivortex pairing energies at the transition [33,37].…”

supporting

confidence: 89%

“…[32]. (t-Butylimido)Tris(Diethylamido)-Niobium(V) (TBTDEN) was used as the niobium precursor, which was kept at 100 • C and delivered by a precursor Boost TM system, which introduces argon gas into the precursor cylinder to promote material transfer of the low vapor pressure precursor to the wafer [32]. The deposition cycle consisted of three 0.5 second pulses of boosted TBTDEN followed by 40 seconds of 300 W plasma consisting of 80 sccm hydrogen and 5 sccm nitrogen.…”

Section: Appendix B: Device Fabricationmentioning

confidence: 99%

“…Kinetic inductance (KI) offers a promising alternative source of Kerr nonlinearity arising from the inertia of Cooper pairs in a superconductor, gaining recent interest for microwave quantum applications [25,26], and has also been successfully used for millimeter-wave detection [27,28]. Niobium Nitride (NbN) is an ideal material for KI, as it has a high intrinsic sheet inductance [29][30][31], a relatively high T c between 14-18 K [29][30][31][32] making it suitable for high-frequency applications [14], and has good microwave loss properties [33]. Among deposition methods, atomic layer deposition (ALD) offers conformal growth of NbN [32] and promising avenues for realizing repeatable high KI devices on a wafer-scale [25].…”

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Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices

et al. 2020

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Millimeter-wave superconducting devices offer a platform for quantum experiments at temperatures above 1 K, and new avenues for studying light-matter interactions in the strong coupling regime. Using the intrinsic nonlinearity associated with kinetic inductance of thin film materials, we realize four-wave mixing at millimeter-wave frequencies, demonstrating a key component for superconducting quantum systems. We report on the performance of niobium nitride resonators around 100 GHz, patterned on thin (20-50 nm) films grown by atomic layer deposition, with sheet inductances up to 212 pH/ and critical temperatures up to 13.9 K. For films thicker than 20 nm, we measure quality factors from 1-6×10 4 , likely limited by two-level systems. Finally we measure degenerate parametric conversion for a 95 GHz device with a forward efficiency up to +16 dB, paving the way for the development of nonlinear quantum devices at millimeter-wave frequencies.For superconducting quantum circuits, the millimeterwave spectrum presents a fascinating frequency regime between microwaves and optics, giving access to a wider range of energy scales, and lower sensitivity to thermal background noise due to higher photon energies. Many advances have been made refining microwave quantum devices [1,2], typically relying on ultra-low temperatures in the millikelvin range to reduce sources of noise and quantum decoherence. Using millimeter-wave photons as building blocks for superconducting quantum devices offers transformative opportunities by allowing quantum experiments to be run at liquid Helium-4 temperatures, allowing higher device power dissipation and enabling large scale direct integration with semiconductor devices [2]. Millimeter-wave quantum devices could also provide new routes for studying strong-coupling light-matter interactions in this frequency regime [3][4][5][6][7], and present new opportunities for quantum-limited frequency conversion and detection [8,9].Recent interest in next-generation communication devices [10, 11] has led to important advances in sensitive millimeter-wave measurement technology around 100 GHz. Realizing quantum systems at these frequencies however requires both the demonstration of lowloss components -device materials with low absorption rates [12][13][14] and resonators with long photon lifetimes [15-20] -and most importantly, elements providing nonlinear interactions, which for circuit quantum optics can be realized with four-wave mixing Kerr terms in the Hamiltonian. One approach commonly used at microwave frequencies relies on aluminum Josephson junctions [2], which yield necessary four-wave mixing at low powers. However to avoid breaking Cooper pairs with high-frequency photons, devices at millimeter-wave frequencies are limited to materials with higher superconducting critical temperatures (T c ). Higher T c junctions have been implemented as high-frequency mixers for millimeter-wave detection [9,21,22], and ongoing efforts are improving losses for quantum applications [23,24].Kinetic inductance (KI)...

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confidence: 89%

Section: Appendix B: Device Fabricationmentioning

confidence: 99%

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confidence: 99%

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Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices

et al. 2020

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“…Also, previously, it has been demonstrated that usage of the metalorganic precursor ( t BuN)2(Me2N)2W along with N2, H2/N2 and NH3 plasmas for a WNx ALD process have resulted in very low levels of carbon impurities (<2 at.%). 32 Here, we provide a detailed study on the tungsten trioxide ALD process and the material properties of the as-deposited material. The influence of deposition temperature on GPC, chemical composition, stoichiometry and optical properties of the resulting WO3 films is investigated.…”

Section: Introductionmentioning

confidence: 99%

Plasma-enhanced atomic layer deposition of tungsten oxide thin films using (tBuN)2(Me2N)2W and O2 plasma

Balasubramanyam

Sharma

Vandalon

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The best results combining the highest T c as well as the lowest resistivity are achieved at the substrate temperature of 300 • C and 300 W plasma power. More details on the preparation process including other optimized parameters could be found in Ref 47 . Figure 1(a) plots the measured NbN film thickness with respect to the number of deposition cycles.…”

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confidence: 99%

Superconducting nanowire single-photon detectors fabricated from atomic-layer-deposited NbN

Cheng

Wang

Tang

2019

Applied Physics Letters

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High-quality ultra-thin films of niobium nitride (NbN) are developed by plasma-enhanced atomic layer deposition (PEALD) technique. Superconducting nanowire single-photon detectors (SNSPDs) patterned from this material exhibit high switching currents and saturated internal efficiencies over a broad bias range at 1550 nm telecommunication wavelength. Statistical analyses on hundreds of fabricated devices show near-unity throughput yield due to exceptional homogeneity of the films. The ALD-NbN material represents an ideal superconducting material for fabricating large single-photon detector arrays combining high efficiency, low jitter, low dark counts.Superconducting nanowire single-photon detectors (SNSPDs) 1,2 have gained widespread attention due to their excellent performances, including high efficiency 3-6 , fast speed 7,8 , exceptional timing jitter 9-11 and ultra-low dark count rates 12,13 . In addition, their suitability for on-chip integration with various nanophotonics circuits 14-23 as well as their photon number resolving 24-26 and spectral 27-29 resolving capability render them an ideal choice for applications in quantum optics, quantum communications and quantum information processing [30][31][32] .The SNSPD is typically a narrow nanowire (20 nm -150 nm width) patterned from an ultra-thin superconducting film (3-10 nm thickness) for absorbing incident photons. So far, two main classes of superconducting materials have been utilized to fabricate high-efficiency SNSPDs: (1) poly-crystalline nitride superconductors such as NbN 4,15,33 and NbTiN 5,16,34-36 ;(2) amorphous alloy superconductors, such as WSi 3,37 , MoSi 6,11,21,38,39 and MoGe 40 . Each of these two classes of materials has their advantages and drawbacks in photon detection. The amorphous films have smaller superconducting energy gap and lower electron density, which tends to create larger photon-excited hot spots in the nanowires and thus results in better saturated internal efficiency. The structural homogeneity due to the absence of grain boundaries in these films further enables the fabrication of large-area detector arrays without suffering from serious constrictions 41,42 . The drawback is their relatively lower superconducting transition temperature T c (< 5 K for thin films) which sets their operation temperature below 2.5 K in order to achieve saturated efficiency at 1550 nm wavelength 43 . Poly-crystalline Nb(Ti)N-based detectors, on the other hand, have higher T c , higher critical current, relatively improved jitter performance and more immunity to latching at high operation speed due to their shorter hot spot relaxation time [44][45][46] . Consequently, Nb(Ti)N was exploited in the recent demonstration of GHzcounting-rate detectors 7,8 and sub-3 ps timing jitter 9 .In this Letter, we show our development of high-quality NbN thin films by plasma-enhanced atomic layer deposition (PEALD) and their applications in SNSPDs fabrication. The fabricated detectors demonstrate broad saturated plateaus in the efficiency curves that are compara...

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Plasma-enhanced atomic layer deposition of superconducting niobium nitride

Cited by 23 publications

References 41 publications

Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices

Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices

Plasma-enhanced atomic layer deposition of tungsten oxide thin films using (tBuN)2(Me2N)2W and O2 plasma

Superconducting nanowire single-photon detectors fabricated from atomic-layer-deposited NbN

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