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Yanyu Jia, Guo Yu, Tiancheng Song, Fang Yuan, Ayelet J. Uzan, Yue Tang, Pengjie Wang, Ratnadwip Singha, Michael Onyszczak, Zhaoyi Joy Zheng, [Kenji Watanabe](https://orcid.org/0000-0003-3701-8119), [Takashi Taniguchi](https://orcid.org/0000-0002-1467-3105), Leslie M. Schoop, Sanfeng Wu

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[Superconductivity from On-Chip Metallization on 2D Topological Chalcogenides](https://mdr.nims.go.jp/datasets/9a72d477-d8dc-410a-b8b0-1fdec6575d18)

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Superconductivity from On-Chip Metallization on 2D Topological ChalcogenidesSuperconductivity from On-Chip Metallization on 2D Topological ChalcogenidesYanyu Jia ,1,* Guo Yu,1,2 Tiancheng Song ,1 Fang Yuan,3 Ayelet J. Uzan,1 Yue Tang,1 Pengjie Wang ,1Ratnadwip Singha,3 Michael Onyszczak,1 Zhaoyi Joy Zheng ,1,2 Kenji Watanabe,4Takashi Taniguchi,5 Leslie M. Schoop,3 and Sanfeng Wu1,†1Department of Physics, Princeton University, Princeton, New Jersey 08544, USA2Department of Electrical and Computer Engineering, Princeton University,Princeton, New Jersey 08544, USA3Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA4Research Center for Electronic and Optical Materials, National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan5Research Center for Materials Nanoarchitectonics, National Institute for Materials Science,1-1 Namiki, Tsukuba 305-0044, Japan(Received 19 December 2023; revised 3 March 2024; accepted 25 April 2024; published 21 June 2024)Two-dimensional (2D) transition metal dichalcogenides (TMDs) is a versatile class of quantum materialsof interest to various fields including, e.g., nanoelectronics, optical devices, and topological and correlatedquantum matter. Tailoring the electronic properties of TMDs is essential to their applications in manydirections. Here, we report that a highly controllable and uniform on-chip 2D metallization processconverts a class of atomically thin TMDs into robust superconductors, a property belonging to none of thestarting materials. As examples, we demonstrate the introduction of superconductivity into a class of 2Dair-sensitive topological TMDs, including monolayers of Td-WTe2, 1T0-MoTe2, and 2H-MoTe2, as well astheir natural and twisted bilayers, metallized with an ultrathin layer of palladium. This class of TMDs isknown to exhibit intriguing topological phases ranging from topological insulator, Weyl semimetal tofractional Chern insulator. The unique, high-quality two-dimensional metallization process is based on ourrecent findings of the long-distance, non-Fickian in-plane mass transport and chemistry in 2D that occurat relatively low temperatures and in devices fully encapsulated with inert insulating layers. Highlycompatible with existing nanofabrication techniques for van der Waals stacks, our results offer a route todesigning and engineering superconductivity and topological phases in a class of correlated 2D materials.DOI: 10.1103/PhysRevX.14.021051 Subject Areas: Condensed Matter Physics,Strongly Correlated Materials,Topological InsulatorsI. INTRODUCTIONIntroducing and designing superconductivity in non-superconducting quantum materials are often desiredfor engineering new phases of matter and superconducting(SC) quantum devices. A prominent example is the hopeto create non-Abelian anyons in artificial nanostructures[1–3]. For instance, introducing superconductivity to atopological insulator has been proposed for realizing thelong-sought-after Majorana zero modes [3–5], an Ising typeof anyons that can be used for demonstrating non-Abelianbraiding statistics and partial operations of a topologicalquantum bit. In more ambitious theoretical proposalscombining superconductivity and fractional quantumHall edge states, one may in principle realize distincttypes of non-Abelian states, such as the parafermionmodes [2,6–9], which could achieve full operations of atopological quantum bit. However, many proposals requirehigh-quality designable integration of superconductorswith topological quantum materials, representing a keychallenge from device engineering perspectives.Conventional approaches of depositing a superconduct-ing metal to the surface of a material [Fig. 1(a)] have beenemployed in, e.g., the nanowire [10], quantum well [11],and graphene systems [12], to name a few. However, for aclass of air-sensitive two-dimensional (2D) materials, thistechnique faces severe challenges in producing high-quality devices. Recent studies have shown that super-conducting compounds may be created at the contactvicinity between a deposited metal and a layered material*yanyuj@princeton.edu†sanfengw@princeton.eduPublished by the American Physical Society under the terms ofthe Creative Commons Attribution 4.0 International license.Further distribution of this work must maintain attribution tothe author(s) and the published article’s title, journal citation,and DOI.PHYSICAL REVIEW X 14, 021051 (2024)Featured in Physics2160-3308=24=14(2)=021051(8) 021051-1 Published by the American Physical Societyhttps://orcid.org/0000-0001-6061-8441https://orcid.org/0000-0002-6845-6624https://orcid.org/0000-0002-1427-6599https://orcid.org/0000-0001-7016-4447https://crossmark.crossref.org/dialog/?doi=10.1103/PhysRevX.14.021051&domain=pdf&date_stamp=2024-06-21https://doi.org/10.1103/PhysRevX.14.021051https://doi.org/10.1103/PhysRevX.14.021051https://doi.org/10.1103/PhysRevX.14.021051https://doi.org/10.1103/PhysRevX.14.021051https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/due to interfacial reactions [13–17] [Fig. 1(b)]. The super-conducting contact created in this process is, however,nonuniform and of small volume attached to a bulknonsuperconducting metal. In a study of multilayer WTe2Josephson junctions employing this method, an additionalsuperconducting metal was deposited to improve the trans-port quality of the device [13]. Similar efforts have alsobeen put forward in introducing superconductivity inepitaxy-grown topological insulators [18–21]. Super-conductivity at low carrier densities may also be realizedby electrostatic gating in novel 2D materials, e.g., mono-layer WTe2 [22,23] and magic-angle graphene systems[24–26] [Fig. 1(c)]. However, these outstanding situationsare rare and unlikely to be generalized to the diverse familyof 2D quantum materials.Here, we report the creation of robust superconductivityin a class of 2D transition metal dichalcogenides (TMDs)metallized with a uniform layer of atomically thin palla-dium. The results are based on our recent surprising finding[27] of a rapid, long-distance, non-Fickian (hence, non-diffusive) in-plane transport of metal films on monolayerTMDs at temperatures well below the melting points ofall materials involved. The process realizes on-chip 2Dchemical synthesis templated on monolayer crystals[Fig. 1(d)], based on which we demonstrate its capabilityin introducing superconductivity into 2D materials. Wecharacterize the electronic properties of the resultant new2D compounds created in topological chalcogenides,including Pd-metallized monolayer and bilayer Td-WTe2,monolayer 1T0-MoTe2, monolayer and twisted bilayer2H-MoTe2, and find superconductivity in all these cases.II. RESULTSA. Superconductivity in 2D Pd-metallized WTe2WTe2 monolayer is an excitonic topological insulatorexhibiting the quantum spin Hall effect [28–33].Introducing superconductivity to its helical edge mode isproposed as a route to topological superconductivity andMajorana zero modes [4,5]. Superconductivity has beenpreviously found in monolayer WTe2 under electrostaticgating [22,23], in which superconducting properties aresensitive to carrier density. Here, we show a distinctapproach for introducing superconductivity to monolayerand bilayer WTe2 based on the on-chip 2D metallizationand crystal growth method [27]. The experiments start with(a) (b) (c)(d)FIG. 1. On-chip two-dimensional metallization on atomically thin topological chalcogenides. (a)–(c) List of known approaches forintroducing superconductivity to nonsuperconducting materials, including direct metal deposition of metal superconductors (a) in alarge chamber, interfacial reaction that produces superconducting compound at contact (b), and the rare cases of gate-inducedsuperconductivity (c). (d) Our approach of on-chip 2D metallization, based on the recent finding of the long-distance non-Fickian 2Dmass transport of Pd at relatively low temperatures (Ref. [27]). The process converts regions of 2D TMDs, e.g., MTe2 (M ¼ W;Mo),into a new superconducting compound PdxMTe2, in a controllable and designable fashion.YANYU JIA et al. PHYS. REV. X 14, 021051 (2024)021051-2fabricating a van der Waals (vdW) stack consisting ofmechanically exfoliated monolayer or bilayer WTe2 andhexagonal boron nitride (h-BN), placed on top of a SiO2=Sisubstrate. Inside the stack, Pd seed islands, in contact withWTe2, are predeposited using standard nanolithographytechniques. Upon heating the stack at ∼200 °C, a subnan-ometer-thick layer of Pd transports from the seeds andspreads uniformly over the entire 2D flake in about an hour[Figs. 2(a) and 2(b)]. This anomalous mass transport andthe resulting new crystalline compound, with a chemicalcomposition Pd7WTe2, were characterized in a previouswork [27]. Here, we report the electronic transport proper-ties of the new compound and find that it is a super-conductor at ultralow temperatures. It is interesting to notethat neither of the starting materials (WTe2 and Pd)superconduct in their pristine forms.Figure 2(c) plots the four-probe resistance (Rxx) as afunction of temperature (T) measured on Pd7WTe2 in-0.8 -0.4 0 0.4 0.800.751.5dV/ dI(k Ω) (e)I (μA)-150-75075150Vxx( μV)(d)T = 50 mKD1D1T (K)0 0.4 0.8 1.200.40.81.2Rxx(kΩ)Tc = 0.45 KTc = 0.9 KPd7WTe2(Pd + 1L WTe2) D1    ×5D2Pd7WTe2(Pd + 2L WTe2)(c)1 μmPd7WTe21L WTe2Pd7WTe2Pd(a)1L WTe2As fabricated T = 210°C, 25 min T = 210°C, 65 minD1Pd1L WTe24 μmPd7WTe2(b)As fabricated T = 250°C, 85 min-0.8 -0.4 0 0.4 0.8-0.6-0.300.30.6B( T)I (μA)T = 50 mK(f) D1dV/dI (kΩ)0 0.60.3-15-7.507.515n g(1012cm-2)-1.5 -0.75 0 0.75 1.5I (μA)(h)T = 50 mKD3dV/dI (kΩ) 0 10.550 mK500 mKStep50 mK0 0.2 0.4 0.60100200B (T)Rxx(Ω)(g) D150 mK600 mKStep50 mKTTh-BNPd 1L WTe2sdVxxFIG. 2. Superconductivity in Pd7WTe2. (a) Optical images of a device demonstrating the on-chip metallization process for amonolayer (1L) WTe2 placed on top of Pd seeds, encapsulated by h-BN. WTe2 is large and covers the whole imaging window. Left: thedevice as fabricated. Middle: an image of the device after heat treatment at ∼210 °C for 25 min. Right: after 65 min (WTe2 inside thewindow is fully converted to Pd7WTe2). The characterization of this process and the new Pd7WTe2 compound are discussed inRef. [27]. (b) A similar process for another device (D1), before (left-hand image) and after (right-hand image) the heat treatment. Here,the Pd leads also serve as transport electrodes. (c) Rxx of Pd7WTe2 measured for D1 (blue, seeded on monolayer WTe2) and D2 (red,seeded on bilayer WTe2), as a function of temperature. (d) Nonlinear IV curves (top, at different T) and (e) differential resistance dV=dI,as a function of applied dc current I, demonstrating the effect of critical currents. (f) A dV=dI map that reveals the vanishing criticalcurrents under magnetic fields B. (g) Rxx as a function of B, taken at various T. (h) dV=dI versus I, taken over the entire gate range in D3with gate electrodes, revealing no gate dependence.SUPERCONDUCTIVITY FROM ON-CHIP METALLIZATION … PHYS. REV. X 14, 021051 (2024)021051-3device D1 (seeded on monolayer WTe2) and D2 (seededon bilayer WTe2). D1 displays a characteristic resistancedrop to zero near Tc ∼ 0.45 K, at which Rxx is half of itsnormal state value. The bilayer seeded Pd7WTe2 (D2)exhibits a higher Tc ∼ 0.9 K. The superconducting non-linear IV curves, as well as differential resistance, areshown in Figs. 2(d) and 2(e), revealing a critical current of∼0.4 μA in this device. A perpendicular magnetic fieldfully suppresses superconductivity at Bc ∼ 0.4 T [Figs. 2(f)and 2(g)]. These observations confirm superconductivity inthis new compound. We have also fabricated a dual-gateddevice (D3), in which we can electrostatically vary theelectron density ng in Pd7WTe2 by ∼� 1.5 × 1013 cm−2.Within this entire range, we find no change in the super-conducting properties [Fig. 2(h)], implying a high carrierdensity in the sample. This is in sharp contrast to the gate-induced low-density superconductivity [22,23] in mono-layer WTe2, which develops a strong insulator state in theabsence of gating-induced doping (ng ∼ 0) [32]. Also, thecritical magnetic field found in Pd7WTe2 is much largerthan that found in the gate-induced superconductivity[22,23] in intrinsic monolayer WTe2, further confirminga distinct origin. We further note that in our Pd7WTe2device [D1, Fig. 2(b)] the data are taken when themonolayer WTe2 is fully converted to Pd7WTe2, so thereis no longer WTe2 in the device. The atomic structure ofW-Te-Win Pd7WTe2 is completely different from the pristineWTe2 [27]. InSupplementalMaterial Fig. S1,we characterizethe superconducting properties of the bilayer seededPd7WTe2 (D2) [34]. In Supplemental Material Fig. S2, weshow a Fraunhofer-like pattern seen in the critical currentmeasurement, induced by disorders that create an accidentaljunction, demonstrating the superconducting interferenceeffects. In Supplemental Material Fig. S3, we present themeasurement of the vortexNernst effect that directly signifiesthe formation andmotion of superconducting vortices. Thesecomprehensive characterizations establish superconductivityin the new Pd7WTe2 compound.B. Superconductivity in 2D Pd-metallized1T0-MoTe2 and 2H-MoTe2At room temperature, MoTe2 monolayer can be stabi-lized in two different phases, exhibiting either a monoclinic(1T’) or a hexagonal lattice structure (2H). 1T0-MoTe2 isknown as a candidate of Weyl semimetal and developssuperconductivity below 0.1 K [35,36]. In contrast,2H-MoTe2 is a semiconductor, not a superconductor. Wefabricate both monolayer 1T0-MoTe2 (D4) and monolayer2H-MoTe2 (D5) in contact with Pd seeds, fully encapsu-lated with h-BN from the top and bottom.When the stack isplaced at ∼250 °C, Pd rapidly propagates in the 2D planeand reacts with the MoTe2 monolayer flake, just like the Pdtransportation on WTe2. Figures 3(a) and 3(b) displayoptical microscope images of the two devices (D4 and D5)before and after the heat treatment, revealing theconsequence of the Pd metallization. Note that, as wehave emphasized previously, the long-distance transportprocess here must involve chemical affinity between Pdand Te, not a simple physical diffusion. The resulting finalmaterial is a new compound PdxMoTe2 consisting ofPd and atoms from the seed monolayers. Atomic forcemicroscopy suggests that the thickness of the new com-pound is ∼1.5 nm and the thickness increases afterPd metallization is ∼0.8 nm (Supplemental MaterialFig. S4 [34]), close to that of Pd7WTe2 obtained in theWTe2 case, suggesting that x is close to 7 as well in theMoTe2 cases. Further characterizations of the compoundsare necessary to uncover their exact atomic structures inthese two cases, which we leave for future study.Here, we focus on the transport properties of the newmaterials and find that in both cases they superconduct.Figures 3(c)–3(e) plot four-probe resistance measuredon a Pd-metallized monolayer 1T0-MoTe2, showing a Tc ∼0.45 K and a Bc ∼ 0.4 T. Similar values are observed inPd-metallized monolayer 2H-MoTe2 [Figs. 3(f)–3(h)]. Thenormal state resistance Rn of these two devices is, however,quite different, being ∼800 Ω for D4 whereas ∼33 Ω forD5. This could be an indication that the resulting materialsin the two cases may not be identical, although the transportdevice geometry plays a role. Consistent with the normalstate resistance, the critical current in D4 (Ic ∼ 100 nA) ismuch smaller than that of D5 (Ic ∼ 1 μA), and conse-quently IcRn does not differ by too much, consistent withthe fact that Tc is similar. It is possible that superconduc-tivity resides on the Pd-Te layer formed in the structure.We note that in our high-resolution scanning transmissionelectron image of the Pd7WTe2 compound, no latticestructure can be identified as a single layer of knownPdTe or PdTe2 crystals [27]. Another possibility is that thesuperconductivity resides on the 2D Pd layer. Even thoughbulk Pd does not superconduct, the ultrathin Pd realized inour case has a unique lattice structure [27] and is possibly asuperconductor. Also note that Pd hydrides superconduct,but this is unlikely the situation as our whole fabricationhappens within an Ar-filled glovebox. We do not have aconclusion on the exact atomic origin of superconductivityat this point, but conclude that the new compound as wholeis a superconductor.C. Designing superconductivity in a fractionalChern insulator (FCI)Recently, the fractional quantum anomalous Hall(FQAH) effect, a zero-magnetic field analog of fractionalquantum Hall effect expected for fractional Chern insula-tors (FCIs), has been discovered in bilayer 2H-MoTe2twisted at an interlayer angle of 3°–4° after a series ofexperiments at University of Washington that uncovered itsmagnetism [37], Chern number [38], and the fractionallyquantized Hall transport [39]. The thermodynamic evi-dence [40] and quantized Hall transport [41] of the FCIs inYANYU JIA et al. PHYS. REV. X 14, 021051 (2024)021051-4the same system have also been reported by two groups atCornell University and Shanghai Jiao Tong University,respectively. This is an exciting development in the field oftopological and correlated phases of matter. One nextquestion is to ask whether there will be interesting newphenomena if superconductivity is introduced to suchsystems. Theoretically, this could offer a possibility torealize new fractionalized electronics state, such as paraf-ermion modes [2,6–9]. It is not yet known how to introducesuperconductivity into this highly interesting but air-sensitive 2Dmaterial system.Conventional approaches basedon deposition of elemental superconductors are difficultwithout reducing its quality. Here, we demonstrate that ouron-chip 2D Pd metallization introduces superconductivityinto twisted bilayer 2H-MoTe2 in a designable fashion.We fabricate twisted bilayer 2H-MoTe2 (D6) at anangle of ∼3.7° (determined using optical images duringfabrication) that favors the FCI states upon electrostaticgating, in contact with predeposited Pd stripes whichserve as both the Pd seeds and the electrodes for transportmeasurement [Fig. 4(a)]. Figures 4(b) and 4(c) showoptical microscope images of the device before and afterheat treatments at 220 °C for 40 min, during which in-plane Pd transport occurs similarly to previous situations.Note that pristine monolayer and twisted bilayer2H-MoTe2 are insulators (see Supplemental MaterialFig. S5 for characterization of the contact propertiesbefore and after a slight Pd transport [34]). With the Pdtreatment, the resulting material turns into a metal thatdevelops superconductivity with Tc ∼ 1 K and Bc ∼ 1 T,00.51Rxx(kΩ)T (K)0.1 0.3 0.50.5 T0.4 T0.3 T0.2 T0.1 T0 T(c)-0.2 -0.1 0 0.1 0.20.10.30.5dV/dI (kΩ)0 31.5T(K)I (uA)0510dV/dI(kΩ)(d)(e)-2 -1 0 1 2dV/dI (Ω)0 10050(g)(h)T = 50 mKdV/dI(Ω)050100I (uA)0.10.30.5T(K)(b)MoTe2H-MoTe2D5h-BN2HMoTe2 PdAs fabricated T = 270°C, 30 minPdPdxMoTe21L 2H-MoTe25 μm(a) 1T’–MoTe2As fabricatedD4T = 250°C, 60 min2 μmPdxMoTe2MoTeh-BN 1T’MoTe2Pd1L 1T’-MoTe2PdT (K)0.1 0.5 0.902040Rxx(Ω)(f)0.4 T0.35 T0.3 T0.25 T0.2 T0.15 T0.1 T0.05 T0 TBBsdVxxdVxxsT = 50 mKFIG. 3. Superconductivity in PdxMoTe2. (a) Optical images of a device (D4) for Pd metallization on monolayer 1T0-MoTe2, before(left) and after (right) the heat treatment. The crystal structure of 1T0-MoTe2 is shown on the top. With Pd coverage, the monolayerregion become darker, signifying the formation of the new compound PdxMoTe2. (b) The same as (a), but for 2H-MoTe2. (c) Rxx ofPdxMoTe2 as a function of T, taken from D4 at various magnetic fields. (d) dV=dI map under varying I and T. (e) dV=dI versus I at50 mK. A dip around ∼� 0.13 μA is seen in (e), featuring a negative dV=dI (note that this is not a negative resistance, but a differentialresistance), which signifies a voltage perturbation due to superconducting transition in a neighboring region and hence inhomogeneity inthis specific sample. (f)–(h) The dataset for 2D Pd-metallized compound on monolayer 2H-MoTe2 (D5).SUPERCONDUCTIVITY FROM ON-CHIP METALLIZATION … PHYS. REV. X 14, 021051 (2024)021051-5as characterized in Fig. 4). IcRn observed in this bilayercase is much larger than that of the monolayer seededPd compounds, indicating a larger superconducting gap,consistent with the higher Tc and Bc. In the SupplementalMaterial Fig. S6, we include data taken from the samedevice but under in-plane magnetic fields, in whichsuperconductivity can survive >10 T, consistent the2D nature of the superconductor [34].We further note that the resistance transition of ourPdxMTe2 superconductors typically occurs within ∼0.2 K.This is much sharper than, for example, the superconduct-ing transition in magic-angle graphene [24], indicating abetter homogeneity in our case. In some of our devices, asingle Ic peak is seen [e.g., Figs. 2(e) and 4(e)], but othersdevelop multiple peaks [e.g., Figs. 3(e) and 3(h)], sug-gesting that inhomogeneity in different devices is different,as expected. We in general find that PdxMTe2 grown onbilayer MTe2 exhibits a better uniformity than that grownon monolayers.Our results establish a feasible device fabricationapproach to study the interplay between superconductivityand FCIs in a highly designable fashion. In this device(D6), we have already realized a loop-shaped supercon-ductor [Fig. 4(c)], the center of which is still intrinsictwisted bilayer 2H-MoTe2 that can be gate tuned into FCIs.The properties of a device interfacing an FCI and asuperconductor in a lateral junction are of interest tothe construction and search of non-Abelian anyons.(b)Rxx(Ω)(d)T (K)0 0.5 1 1.50100200Tc = 1.05 K-1-0.500.51-2 -1 0 1 2B(T)dV/dI (Ω)0 700350(e)I (uA)As fabricatedPdD6BottomMoTe2TopMoTe2(a)Twisted bilayer 2H-MoTe22H-MoTe2h-BNGrPd R(Ω)θ ~ 3.7°FQAHPdxMoTe2SCI (uA)-2 -1 0 1 2Vxx(μV)5002500-250-5000.1 K1.2 KStep0.1 KT0 0.75 1.50100200B┴ (T)Rxx(Ω)(g)0.1 K1.2 KStep0.1 KT(c) PdxMoTe2Twisted bilayer2H-MoTe2T = 220°C40 min 5 μm0100200Rxx(Ω)0.1 0.7 1.3T (K)(f)0 T1.3 TStep0.1 TBdVxxsFIG. 4. Designing superconductivity in a fractional Chern insulator. (a) Top: an illustration of an in-plane heterojunction of asuperconductor and a fractional Chern insulator realized in twisted bilayer 2H-MoTe2. The moiré lattice is shown to the left. (b),(c)Optical images of a device (D6) consist of Pd stripes (electrodes) and twisted bilayer 2H-MoTe2, fully encapsulated with graphite andhBN stacks, before (b) and after (c) the heat treatment. (d) Rxx versus T for PdxMoTe2 realized in D6, revealing the superconductingtransition. Inset shows the nonlinear IV curves taken at various T, displaying sharp jumps. The contact configuration used in themeasurement is shown in (c). (e) A dV=dI map taken under varying B and I. (f) Rxx versus T taken under various B. (g) Rxx versus Btaken at various T.YANYU JIA et al. PHYS. REV. X 14, 021051 (2024)021051-6We envision fruitful future explorations along this directionbased on the approach and device presented here as well astheir variations.III. DISCUSSIONBeyond palladium, we have tested the phenomena onother metals. We do not find propagation of Au on WTe2 atsimilar temperatures (Supplemental Material Fig. S7 [34]).We find Ni does propagate similarly on WTe2 , but theresulting new compound does not superconduct down to∼50 mK despite being metallic (Supplemental MaterialFig. S8). The magnetic properties of the Ni-based com-pound, however, deserve further studies.Our results establish a method of introducing super-conductivity into a class of 2D topological chalcogenides.The rich topological phases and strong gate tunability ofthe host 2D materials distinguish our approach from theprevious attempts in proximitizing epitaxy-grown topo-logical insulators. The size and shape of the superconduct-ing islands can be controlled via designing the pattern of Pdseeds and manipulating the recipes of the heat treatment.One key feature is that the heat treatment requires only atemperature as low as ∼200 °C, which can be performedstraightforwardly on a hot plate and/or under microscope.The whole process can be done inside a glovebox fordevices on a chip without degrading the quality of sensitivecomponents. We believe this unique approach for designingand creating robust superconductivity for air-sensitive 2Dtopological materials will enable a range of interestingexplorations in condensed matter physics and supercon-ducting quantum devices.ACKNOWLEDGMENTSThis work is supported by AFOSR Young InvestigatorAward (No. FA9550-23-1-0140) to S. W. Electric transportmeasurement is partially supported by NSF through theMaterials Research Science and Engineering Center(MRSEC) program of the National Science Foundation(DMR-2011750) through support to L. M. S. and S.W. anda CAREER Award (No. DMR-1942942) to S. W. Devicefabrication is partially supported by ONR through a YoungInvestigator Award (No. N00014-21-1-2804) to S. W. S.W.and L. M. S. acknowledge support from the Eric andWendy Schmidt Transformative Technology Fund atPrinceton. S. W. acknowledges support from the SloanFoundation. L. M. S. acknowledges support from theGordon and Betty Moore Foundation through GrantNo. GBMF9064 and the David and Lucile PackardFoundation and the Sloan Foundation. Y. J. acknowledgessupport from the Princeton Charlotte Elizabeth ProcterFellowship program. T. S. acknowledges support from thePrinceton Physics Dicke Fellowship program. A. J. U.acknowledges support from the Rothschild Foundationand the Zuckerman Foundation. K.W. and T. T.acknowledge support from the JSPS KAKENHI(Grants No. 21H05233 and No. 23H02052) and WorldPremier International Research Center Initiative (WPI),MEXT, Japan.[1] C. Nayak, S. H. Simon, A. Stern, M. Freedman, and S. 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