Graphene-based Van Der Waals Research Articles

Quantized heat flow in graphene quantum Hall phases: Probing the topological order

Topological quantum numbers are often used to characterize the topological order of phase having protected gapless edge modes when the system is kept in a space with the boundary. The famous examples in this category are the quantized electrical Hall conductance and thermal Hall conductance, which encodes the topological order of integer and fractional quantum Hall states. Here, we review the recent thermal transport study of integer and fractional quantum Hall states realized in graphene-based van der Waals heterostructures.

Electric Dipole Coupling of a Bilayer Graphene Quantum Dot to a High-Impedance Microwave Resonator.

We implement circuit quantum electrodynamics (cQED) with quantum dots in bilayer graphene, a maturing material platform that can host long-lived spin and valley states. Our device combines a high-impedance (Zr ≈ 1 kΩ) superconducting microwave resonator with a double quantum dot electrostatically defined in a graphene-based van der Waals heterostructure. Electric dipole coupling between the subsystems allows the resonator to sense the electric susceptibility of the double quantum dot from which we reconstruct its charge stability diagram. We achieve sensitive and fast detection of the interdot transition with a signal-to-noise ratio of 3.5 within 1 μs integration time. The charge-photon interaction is quantified in the dispersive and resonant regimes by comparing the resonator response to input-output theory, yielding a coupling strength of g/2π = 49.7 MHz. Our results introduce cQED as a probe for quantum dots in van der Waals materials and indicate a path toward coherent charge-photon coupling with bilayer graphene quantum dots.

Electronic structures and quantum capacitance of twisted mixed-dimensional van der Waals heterostructures of graphene/C2H based on tight-binding model

Constructing twisted mixed dimensional graphene-based van der Waals heterostructure (vdWH) is an effective strategy to manipulate the electronic structures and improve the quantum capacitance (C q) of graphene. In this work, mixed dimensional vdWH of graphene/C2H has been proposed owing to similar Dirac semimetal character of one-dimensional C2H with that of graphene. Meanwhile, the influence of twisting angle (θ) and interlayer interaction strength on the electronic structures and the C q of the MD vdWH are systemically explored based on tight binding model. With the fitted hopping integral parameters, it is found that the linear dispersion of the graphene is basically preserved but the bandwidth is decreased with modulating twisting angle and interlayer interaction, and the C q of mixed dimensional vdWH is improved 5–19 times compared with graphene at zero bias. Moreover, the compressed strain could enhance the C q of mixed dimensional vdWH to 74.57 μF cm−2 at zero bias and broaden the low working voltage window of mixed-dimensional vdWH with considerable C q. Our results provide suitable tight-binding model parameters and theoretical guidance for exploring the twisted MD vdWH of graphene/C2H and offer an effective strategy to modulate the electronic structures and the C q of graphene through constructing the MD vdWH.

Probing the Inelastic Electron Tunneling via the Photocurrent in a Vertical Graphene van der Waals Heterostructure.

Inelastic electron tunneling (IET), accompanied by energy transfer between the tunneling charge carriers and other elementary excitations, is widely used to investigate the collective modes and quasiparticles in solid-state materials. In general, the inelastic contribution to the tunneling current is small compared to the elastic part and is therefore only prominent in the second derivative of the tunneling current with respect to the bias voltage. Here we demonstrate a direct observation of the IET by measuring the photoresponse in a graphene-based vertical tunnel junction device. Characteristic peaks/valleys are observed in the bias-voltage-dependent tunneling photocurrent at low temperatures, which barely shift with the gate voltage applied to graphene and diminish gradually as the temperature increases. By comparing with the second-order differential conductance spectra, we establish that these features are associated with the phonon-assisted IET. A simple model based on the photoexcited hot-carrier tunneling in graphene qualitatively explains the response. Our study points to a promising means of probing the low-energy elementary excitations utilizing the graphene-based van der Waals (vdW) heterostructures.

Stacking transfer of wafer-scale graphene-based van der Waals superlattices

High-quality graphene-based van der Waals superlattices are crucial for investigating physical properties and developing functional devices. However, achieving homogeneous wafer-scale graphene-based superlattices with controlled twist angles is challenging. Here, we present a flat-to-flat transfer method for fabricating wafer-scale graphene and graphene-based superlattices. The aqueous solution between graphene and substrate is removed by a two-step spinning-assisted dehydration procedure with the optimal wetting angle. Proton-assisted treatment is further used to clean graphene surfaces and interfaces, which also decouples graphene and neutralizes the doping levels. Twist angles between different layers are accurately controlled by adjusting the macroscopic stacking angle through their wafer flats. Transferred films exhibit minimal defects, homogeneous morphology, and uniform electrical properties over wafer scale. Even at room temperature, robust quantum Hall effects are observed in graphene films with centimetre-scale linewidth. Our stacking transfer method can facilitate the fabrication of graphene-based van der Waals superlattices and accelerate functional device applications.

Surface-acoustic-wave-driven graphene plasmonic sensor for fingerprinting ultrathin biolayers down to the monolayer limit

Surface plasmon polaritons in graphene can enhance the performance of mid-infrared spectroscopy, which is key for the study of both the composition and the conformation of organic molecules via their vibrational resonances. In this paper, a plasmonic biosensor using a graphene-based van der Waals heterostructure on a piezoelectric substrate is theoretically demonstrated, where far-field light is coupled to surface plasmon-phonon polaritons (SPPPs) through a surface acoustic wave (SAW). The SAW creates an electrically-controlled virtual diffraction grating, suppressing the need for patterning the 2D materials, that limits the polariton lifetime, and enabling differential measurement schemes, which increase the signal-to-noise ratio and allow a quick commutation between reference and sample signals. A transfer matrix method has been used for simulating the SPPPs propagating in the system, which are electrically tuned to interact with the vibrational resonances of the analytes. Furthermore, the analysis of the sensor response with a coupled oscillators model has proven its capability of fingerprinting ultrathin biolayers, even when the interaction is too weak to induce a Fano interference pattern, with a sensitivity down to the monolayer limit, as tested with a protein bilayer or a peptide monolayer. The proposed device paves the way for the development of advanced SAW-assisted lab-on-chip systems combining the existing SAW-mediated physical sensing and microfluidic functionalities with the chemical fingerprinting capability of this novel SAW-driven plasmonic approach.

Casimir-Polder interactions of S -state Rydberg atoms with graphene

We investigate the thermal Casimir-Polder (CP) potential of $^{87}\mathrm{Rb}$ atoms in Rydberg $nS$-states near single- and double-layer graphene, and briefly look into the lifetimes near graphene-hexagonal boron nitride (hBN) multilayered structures. The dependence of the CP potential on parameters such as atom-surface distance, temperature, principal quantum number $n$, and graphene Fermi energy are explored. Through large-scale numerical simulations, we show that, in the nonretarded regime, the CP potential is dominated by the nonresonant and evanescent-wave terms which are monotonic, and that, in the retarded regime, the CP potential exhibits spatial oscillations. We identify that the most important contributions to the resonant component of the CP potential come from the $nS\text{\ensuremath{-}}nP$ and $nS\text{\ensuremath{-}}(n\ensuremath{-}1)P$ transitions. Scaling of the CP potential as a function of the principal quantum number and temperature is obtained. A heterostructure comprising hexagonal boron nitride layers sandwiched between two graphene layers is also studied. When the boron nitride layer is sufficiently thin, the CP potential can be weakened by changing the Fermi energy of the top graphene layer. Our study provides insights for understanding and controlling CP potentials experienced by Rydberg atoms near single- and multilayer graphene-based van der Waals heterostructures.

Spin–orbit and exchange proximity couplings in graphene/1T-TaS2 heterostructure triggered by a charge density wave

Proximity-induced fine features and spin-textures of the electronic bands in graphene-based van der Waals heterostructures can be explored from the point of tailoring a twist angle. Here we study spin–orbit coupling and exchange coupling engineering of graphene states in the proximity of 1T-TaS2 not triggering the twist, but a charge density wave (CDW) in 1T-TaS2—a realistic low-temperature phase. Using density functional theory and effective model we found that the emergence of the CDW in 1T-TaS2 significantly enhances Rashba spin–orbit splitting in graphene and tilts the spin texture by a significant Rashba angle—in a very similar way as in the conventional twist-angle scenarios. Moreover, the partially filled Ta d-band in the CDW phase leads to the spontaneous emergence of the in-plane magnetic order that transgresses via proximity from 1T-TaS2 to graphene, hence, simultaneously superimposing along the spin–orbit also the exchange coupling proximity effect. To describe this intricate proximity landscape we have developed an effective model Hamiltonian and provided a minimal set of parameters that excellently reproduces all the spectral features predicted by the first-principles calculations. Conceptually, the CDW provides a highly interesting knob to control the fine features of electronic states and to tailor the superimposed proximity effects—a sort of twistronics without twist.

Valley Hall effect in graphene-like SnX ( X=Si , Ge) buckled monolayers with high charge carrier mobility and low lattice thermal conductivity

A systematic analysis of the electronic and thermal properties of two semiconducting monolayers, SnSi and SnGe, is conducted through the lens of density functional theory. Unlike centrosymmetric graphene, these two monolayers are noncentrosymmetric and buckled in the structure; however, their band dispersion resembles that of graphene with a finite small band gap occurring at the $K$ point of the Brillouin zone. Unlike transition metal dichalcogenide (TMDC) monolayers, the band edges in the studied semiconducting monolayers are devoid of $d$ orbitals and contain $s$ and $p$ orbitals, and thus, the valley spin splitting occurring in these semiconductors is a nontrivial topological effect originating from broken inversion symmetry in the crystal structure, as observed earlier in bilayer graphene or graphene-based van der Waals heterostructures. The electronic properties are found to be tunable via external perturbations like an electric field and biaxial strain. These monolayers are highly flexible, as indicated by the small value of Young's modulus, $<50\phantom{\rule{0.28em}{0ex}}\mathrm{N}/\mathrm{m}$. The charge carrier mobility is calculated within the Boltzmann transport equation and found to be $\ensuremath{\sim}1000\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.28em}{0ex}}{\mathrm{V}}^{\ensuremath{-}}1\phantom{\rule{0.28em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$. The phonon dynamics study indicates a very low value of lattice thermal conductivity at room temperature (i.e., ${\ensuremath{\kappa}}_{l}<1.5\phantom{\rule{0.28em}{0ex}}\mathrm{W}\phantom{\rule{0.28em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.28em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$), which arises from the domination of Umklapp scattering, small group velocity, and low Debye temperature. Such a low value of ${\ensuremath{\kappa}}_{l}$ will facilitate better thermal control than TMDCs or graphene-based devices. In this paper, we indicate that the inherent properties of SnSi and SnGe monolayers, such as valley contrasting properties, high charge carrier mobility, low lattice thermal conductivity, and mechanical flexibility, surpass that of well-known TMDCs (${\mathrm{MoS}}_{2}, {\mathrm{WS}}_{2}$) and boron pnictides (BP, BAs, BSb), thereby motivating their synthesis.

Tunable electronic structures and interface contact in graphene/C<sub>3</sub>N van der Waals heterostructures

Graphene-based van der Waals heterojunctions can not only modulate the electronic properties of graphene but also retain the superior properties of the original monolayer. In this paper, the structure, electrical contact types, electronic and optical properties of graphene/C<sub>3</sub>N van der Waals heterojunctions are systematically investigated based on first-principles calculations. We find that there is a p-type Schottky contact of only 0.039 eV in the graphene/C<sub>3</sub>N van der Waals heterojunctions in an equilibrium state. The external electric field can adjust the interface contact type, specifically, from p-type to n-type Schottky contact, or from p-type Schottky contact to Ohmic contact. The vertical strain not only opens a nonnegligible band gap of 360 meV on the Dirac cone of graphene in graphene/C<sub>3</sub>N van der Waals heterojunctions, but also modulates the band gap of C<sub>3</sub>N in the heterojunctions. Moreover, both the doping type and concentration of the carriers can be effectively tuned by the applied electric field and the vertical strain. The increase in carrier concentration is more pronounced by the applied electric field. Comparing with the pristine monolayer graphene and monolayer C<sub>3</sub>N, the optical response range and the light absorption rate of graphene /C<sub>3</sub>N van der Waals heterojunctions are enhanced. Main absorption peak in the spectrum reaches to 10<sup>6</sup> cm<sup>–1</sup>. These results not only provide valuable theoretical guidance for designing Schottky-based graphene/C<sub>3</sub>N van der Waals heterojunctions devices, but also further explore the potential applications of heterojunctions in optoelectronic nanodevices and field-effect transistor devices.

Weak localisation driven by pseudospin-spin entanglement

At low temperatures, quantum corrections, originating from the interference of the many paths an electron may take between two points, tend to dominate the transport properties of two-dimensional conductors. These quantum corrections increase the resistivity in systems such as two-dimensional electron gases (2DEGs) without spin–orbit coupling (SOC), a phenomenon called weak localisation. Including symmetry-breaking SOC leads to a change from weak localisation (WL) to weak anti-localisation (WAL) of the electronic states, i.e. a WL-to-WAL transition. Here, we revisit the Cooperon, the propagator encoding quantum corrections, within the context of ultra-clean graphene-based van der Waals heterostructures with strong symmetry-breaking Bychkov-Rashba SOC to yield two completely counter-intuitive results. Firstly, we find that quantum corrections vary non-monotonically with the SOC strength, a clear indication of non-perturbative physics. Secondly, we observe the exact opposite of that seen in 2DEGs with strong SOC: a WAL-to-WL transition. This dramatic reversal is driven by mode entanglement of the pseudospin and spin degrees of freedom describing graphene’s electronic states. We obtain these results by constructing a non-perturbative treatment of the Cooperon, and observe distinct features in the SOC dependence of the quantum corrections to the electrical conductivity that would otherwise be missed by standard perturbative approaches.

First-principles studies of the mixed-dimensional van der Waals heterostructures of graphene/MnF4

Constructing a mixed-dimensional (MD) graphene-based van der Waals heterostructure (vdWH) is a viable technique for opening the bandgap and introducing spin polarization in graphene. In this work, we discovered that the adjacent MnF4 can manipulate the carrier doping, bandgap opening, and spin polarization of graphene in the MD vdWH of graphene/MnF4 comprised of two-dimensional (2D) graphene and one-dimensional atomic wire (1D AW) MnF4. By adopting first-principles calculations, we found that graphene can achieve effective p-type doping with the carrier density up to ∼8.89 × 1013–1.03 × 1014 cm−2. With a twisted angle of θ = 10.89° and the compressed distance of dMn-Gra = 2.84 Å, the opened bandgap of graphene (Eg-Gra) achieves 35 and 57 meV for spin-up and spin-down channels due to the sublattice symmetry-breaking in graphene, and the spin splitting energy (ΔES) at the Dirac point reaches 78.7 meV as a result of the graphene–MnF4 interlayer interaction. Remarkably, Eg-Gra is increased to 64 and 79 meV for spin-up and spin-down channels, and ΔES with 202.7 meV is obtained at dMn-Gra = 2.84 Å when the width of 1D MnF4 is doubled. Meanwhile, the n-type Ohmic contact is also realized. Our work underscores the rich interplay in the graphene/MnF4 MD vdWH and provides a significant route with fundamental insights to engineer the spintronic band properties of graphene.

Strain engineering on the electronic properties and interface contact of graphene/GeN3 van der Waals heterostructure

Graphene-based van der Waals (vdW) heterostructures have shown great potential in electronic and optoelectronic nanodevices. Herein, we investigate the electronic property and Schottky barrier of graphene/GeN3 vdW heterostructure by first-principles calculations. It is noted that the electronic natures of graphene and GeN3 monolayers are well preserved in the heterostructure lattice due to the weak vdW interaction. Interestingly, the p-type Schottky contact in graphene/GeN3 heterostructure with a barrier height of 0.21 eV can be effectively tuned by both vertical and horizontal strains. Herein, the carrier concentration in the graphene layer reaches ∼1013 cm−2 level by strain engineering. It is noteworthy that the designed optoelectronic field-effect transistor based on graphene/GeN3 heterostructure exhibits distinguished responsivity of 0.297 AW−1 and impressive external quantum efficiency of 54.5% under illumination based on further non-equilibrium Green's function simulations. Our findings are of utmost significance for the metal–semiconductor vdW contact and corresponding applications in high-performance electronic and optoelectronic devices.

Interlayer coupling and external electric field controllable electronic structures and Schottky contact of HfSeX (X = S, Se)/graphene van der Waals heterostructures

Graphene-based van der Waals heterostructures (vdWHs) owing to their remarkable physical properties and extensive application attract much attention. However, the Schottky barrier height (SBH) at the interface limits the charge injection effect. Here, we investigate the geometry, electronic structures, contact behavior and optical properties of the HfSeX/graphene (HfSeX/G, X = S, Se) vdWHs via first-principles calculations. The effect of interlayer coupling and external electric field (Efield) on the HfSeX/G are examined. Our results show that the Dirac cones of graphene are well preserved in all modes due to weak van der Waals interaction and a small bandgap is opened in graphene. The SBH of n-type Schottky contact types (SCT) HfSe2/G, SHfSe/G and SeHfS/G vdWHs are 0.100, 0.085 and 0.114 eV, respectively. Both the interlayer distance and Efield can induce the n-type SCT of the Janus HfSSe/G to transfer to p-type, and large Efield can cause an Ohmic contact. The HfSeX/G heterostructures enhance light absorption intensity in visible-light region compared with isolate graphene and HfSeX monolayers. The work provides a valuable theoretical guidance for designing Schottky-based devices of the HfSeX/G heterostructures, as well as indicates that the heterostructures have a flexible application prospect in further optoelectronic and field effect transistors devices.

Andreev Reflection in the Fractional Quantum Hall State

We construct high-quality graphene-based van der Waals devices with narrow superconducting niobium nitride (NbN) electrodes, in which superconductivity and robust fqH coexist. We find crossed Andreev reflection (CAR) across the superconductor separating two fqH edges. Our observed CAR probabilities in the particle-like fractional fillings are markedly higher than those in the integer and hole-conjugate fractional fillings and depend strongly on temperature and magnetic field unlike the other fillings. Further, we find a filling-independent CAR probability in integer fillings, which we attribute to spin-orbit coupling in NbN allowing for Andreev reflection between spin-polarized edges. These results provide a route to realize novel topological superconducting phases in fqH-superconductor hybrid devices based on graphene and NbN.

Probing the charge transfer and electron–hole asymmetry in graphene–graphene quantum dot heterostructure

In recent years, graphene-based van der Waals (vdW) heterostructures have come into prominence showcasing interesting charge transfer dynamics which is significant for optoelectronic applications. These novel structures are highly tunable depending on several factors such as the combination of the two-dimensional materials, the number of layers and band alignment exhibiting interfacial charge transfer dynamics. Here, we report on a novel graphene based 0D–2D vdW heterostructure between graphene and amine-functionalized graphene quantum dots (GQD) to investigate the interfacial charge transfer and doping possibilities. Using a combination of ab initio simulations and Kelvin probe force microscopy (KPFM) measurements, we confirm that the incorporation of functional GQDs leads to a charge transfer induced p-type doping in graphene. A shift of the Dirac point by 0.05 eV with respect to the Fermi level (E F) in the graphene from the heterostructure was deduced from the calculated density of states. KPFM measurements revealed an increment in the surface potential of the GQD in the 0D–2D heterostructure by 29 mV with respect to graphene. Furthermore, we conducted power dependent Raman spectroscopy for both graphene and the heterostructure samples. An optical doping-induced gating effect resulted in a stiffening of the G band for electrons and holes in both samples (graphene and the heterostructure), suggesting a breakdown of the adiabatic Born–Oppenheimer approximation. Moreover, charge imbalance and renormalization of the electron–hole dispersion under the additional influence of the doped functional GQDs is pointing to an asymmetry in conduction and carrier mobility.

Modulation of Schottky barrier in XSi2N4/graphene (X = Mo and W) heterojunctions by biaxial strain

Reducing the Schottky barrier height (SBH) and even achieving the transition from Schottky contacts to Ohmic contacts are key challenges of achieving high energy efficiency and high-performance power devices. In this paper, the modulation effects of biaxial strain on the electronic properties and Schottky barrier of MoSi2N4 (MSN)/graphene and WSi2N4 (WSN)/graphene heterojunctions are examined by using first principles calculations. After the construction of heterojunctions, the electronic structures of MSN, WSN, and graphene are well preserved. Herein, we show that by applying suitable external strain to a heterojunction stacked by MSN or WSN — an emerging two-dimensional (2D) semiconductor family with excellent mechanical properties — and graphene, the heterojunction can be transformed from Schottky p-type contacts into n-type contacts, even highly efficient Ohmic contacts, making it of critical importance to unleash the tremendous potentials of graphene-based van der Waals (vdW) heterojunctions. Not only are these findings invaluable for designing high-performance graphene-based electronic devices, but also they provide an effective route to realizing dynamic switching either between n-type and p-type Schottky contacts, or between Schottky contacts and Ohmic contacts.

Chemical vapor deposition of two-dimensional molybdenum nitride/graphene van der Waals heterostructure with enhanced electrocatalytic hydrogen evolution performance

Two-dimensional (2D) ultrathin transition metal nitrides (TMNs) have attracted increasing research interests as a family of rising functional materials for various applications especially energy storage and catalysis. In addition, graphene-based van der Waals (vdW) heterostructures could remarkably promote the catalysis performance compared to the intrinsic TMNs due to the interfacial synergy effect and more efficient charge-transfer kinetics. Here we first report a facile two-step method for synthesis of high-quality molybdenum nitride/graphene (MoN/G) vdW vertical heterostructure through liquid copper-assisted chemical vapor deposition followed by a nitridation process. Graphene not only acts as a Mo diffusion barrier for growth of 2D thin MoN crystals, but also facilitates the charge transport within the heterostructure. Therefore, the as-grown MoN/G heterostructure shows a relatively low overpotential of 155 mV and 259 mV in H2SO4 and KOH solutions, respectively, which indeed exhibits outstanding pH-universal (pH = 0–14) hydrogen evolution reaction (HER) catalytic performance. These results provide a general method for the controllable synthesis of MoN/G heterostructure and promote the further research of TMNs-related catalysts in HER catalysis area.

Effects of electric field on Schottky barrier in graphene and hexagonal boron phosphide heterostructures

Two dimensional graphene-based van der Waals heterostructures have attracted the interest of various researchers due to their unique properties. Based on the contact between metal electrodes and two dimensional materials has a substantial impact on the performance of electronic devices. The interfacial performance and Schottky contact performance with graphene and hexagonal boron phosphide (h-BP) vdW heterostructures are investigated using density functional theory calculations. We investigated eight energy-stable stacking configurations of multilayer graphene and h-BP vdW heterostructures. The different configurations of the h-BP/graphene vdW heterostructures all exhibit n-type Schottky contacts. The band structure of the h-BP in the heterostructures can be modulated under the influence of an external electric field (E field ), thus effectively manipulating the Schottky barrier height (SBH). The n-type SBH increases with the increasing positive E field and eventually the contact transforms into an Ohmic contact, while the Schottky contact transition from n-type to p-type occurs under the negative E field . The data demonstrate that modulating the electronic properties of hexagonal boron phosphide/graphere (h-BP/Gr) vdW heterostructures with E field is a promising approach, which can control the transition from Schottky to Ohmic contacts. The results can provide theoretical support for the design of controlled Schottky nanoelectronic devices. • 2D h-BP/Gr vdW heterostructures possesses a low n-type Schottky barrier height (0.15 eV–0.18 eV). • The transformate heterostructures can be transformed from an n-type Schottky contact to a p-type Schottky contact, then to an Ohmic contact. • The SBH of h-BP/Gr vdW heterostructures can be effectively regulated by an external electric field. • As the number of graphene layers increases the external electric field required for Schottky transition decreases.

Tunable Quantum Tunneling through a Graphene/Bi2Se3 Heterointerface for the Hybrid Photodetection Mechanism.

Graphene-based van der Waals heterostructures are promising building blocks for broadband photodetection because of the gapless nature of graphene. However, their performance is mostly limited by the inevitable trade-off between low dark current and photocurrent generation. Here, we demonstrate a hybrid photodetection mode based on the photogating effect coupled with the photovoltaic effect via tunable quantum tunneling through the unique graphene/Bi2Se3 heterointerface. The tunneling junction formed between the semimetallic graphene and the topologically insulating Bi2Se3 exhibits asymmetric rectifying and hysteretic current–voltage characteristics, which significantly suppresses the dark current and enhances the photocurrent. The photocurrent-to-dark current ratio increases by about a factor of 10 with the electrical tuning of tunneling resistance for efficient light detection covering the major photonic spectral band from the visible to the mid-infrared ranges. Our findings provide a novel concept of using tunable quantum tunneling for highly sensitive broadband photodetection in mixed-dimensional van der Waals heterostructures.