Nonequilibrium Green Function Method Research Articles

Tunable electronic and photodiode characteristics of Janus WSeTe: A first-principles study

Janus transition metal chalcogenides have captured the wide attention due to the asymmetric facial properties. Using the first principles calculations in combination with the nonequilibrium Green's function method, we studied the electronic structure, transport and optical properties of WSeTe monolayer. The results show that the electronic properties of WSeTe monolayer can be effectively regulated by biaxial strain and electric field. To be specific, a phase transition from semiconductor to metal accompanied with direct to indirect gap transition can be achieved by applying the biaxial strain. Besides, the optical properties of WSeTe monolayer can also be significant improved in the visible light region with a red and blue shift of optical absorption peaks under the tensile and compressive strain respectively. For devices based on WSeTe monolayer, the current switching ratios are up to 1010, which represent a perfect diode behavior can be observed in the case of ±12% strain. Furthermore, for pin-junction based on WSeTe monolayer, a considerable photocurrents which can be obtained from the light absorption coefficients located in the scope of 1∼3 eV, mean a strong photoelectronic response to the red and orange light region. The results show great potential for the application of WSeTe monolayer in switching and photoelectric devices.

Interface design of the thermoelectric transport properties of phosphorene-tetrathiafulvalene nanoscale devices.

Interface design and energy band engineering are two key strategies for improving the thermoelectric conversion efficiency of low dimensional nanoscale devices. By using first-principle-based density functional theory combined with a non-equilibrium Green function method, the thermoelectric properties of a single tetrathiafulvalene (TTF) molecule coupled with armchair phosphorene nanoribbons (APNRs) within different interface modes have been investigated. The results indicate that phonon transport can be dramatically suppressed in this intermediate weak-coupling system due to strong interfacial phonon scattering behavior, where very few phonons can propagate through two nonbonded interface regions from left side lead to a TTF molecule and then to right side lead. Furthermore, connecting a thiophene group at both the head and tail of the intermediate TTF molecule can significantly enhance the power factor (S2σ) of such a weak-coupling system based on an out-of-plane electronic transmission mechanism, and there is obvious charge transfer from S atoms to upper and lower APNRs. Compared to a single regular method, composite interface co-design can achieve more accurate control of thermal/electrical transmission performance. Electrical conductance can be effectively improved with low phonon thermal conductance being maintained at the same time, and an excellent thermoelectric figure of merit (ZT) of 0.73 has been obtained near 0.6 eV.

Spin-switching effect and giant magnetoresistance in quantum structure of monolayer MoS<sub>2</sub> nanoribbons with ferromagnetic electrode

Spintronics is a new type of electronics based on electron spin rather than charge as the information carrier, which can be stored and calculated by regulating and manipulating the spin. The discovery and application of the giant magnetoresistance effect opens the door to the application of electron spin properties. Realizing on-demand control of spin degree of freedom for spin-based devices is essential. The two-dimensional novel material, monolayer transition metal dichalcogenide (TMD) (MoS<sub>2</sub> is a typical example from the family of TMD materials), has become an excellent platform for studying spintronics due to its novel physical properties, such as direct band gap and strong spin-orbit coupling. Obtaining high spin polarization and achieving controllability of degrees of freedom are fundamental problems in spintronics. In this paper, we construct the monolayer zigzag MoS<sub>2</sub> nanoribbon quantum structure of electrically controlled ferromagnetic electrode to solve this problem. Based on the non-equilibrium Green’s function method, the regulation of the magnetic exchange field and electrostatic barrier on the spin transport in parallel configuration and anti-parallel configuration are studied. It is found that in the parallel structure, spin transport is obviously related to the magnetic exchange field, and 100% spin filtering can occur near the Fermi energy level to obtain pure spin current. When an additional electric field is applied to the middle region, the spin filtering effect is more significant. Therefore, the spin switching effect can be achieved by regulating the incident energy. In addition, it is also found that within a specific energy range, electrons in the parallel configuration are excited to participate in transport, while electrons in the anti-parallel structure are significantly inhibited. Consequently, a noticeable giant magnetoresistance effect can be obtained in this quantum structure. Moreover, it can be seen that the magnetic exchange field strength can effectively modulate the giant magnetoresistance effect. These results provide valuable theoretical references for the development of giant magnetoresistance devices and spin filters based on monolayer zigzag MoS<sub>2</sub> nanoribbons.

Two -dimensional semimetal AlSb monolayer with multiple nodal-loops and extraordinary transport properties under uniaxial strain.

Two-dimensional (2D) nodal-loop semimetal (NLSM) materials have attracted much attention for their high-speed and low-consumption transporting properties as well as their fantastic symmetry protection mechanisms. In this paper, using systematic first-principles calculations, we present an excellent NLSM candidate, a 2D AlSb monolayer, in which the conduction and valence bands cross with each other forming fascinating multiple nodal-loop (NL) states. The NLSM properties of the AlSb monolayer are protected by its glide mirror symmetry, which was confirmed using a symmetry-constrained six-band tight-binding model. The transport properties of the AlSb monolayer under in-plane uniaxial strains are also studied, based on a non-equilibrium Green's function method. It is found that both compressive and tensile strains from -10% to 10% improve the transporting properties of AlSb, and it is interesting to see that flexure configurations are energetically favored when compressive uniaxial strains are applied. Our studies not only provide a novel 2D NLSM candidate with a new symmetry protection mechanism, but also raise the novel possibility for the detection of out-of-plane flexure in 2D semimetal materials.

Tunnel junction sensing of TATP explosive at the single-molecule level.

Triacetone triperoxide (TATP) is a highly potent homemade explosive commonly used in terrorist attacks. Its detection poses a significant challenge due to its volatility, and the lack of portability of current sensing techniques. To address this issue, we propose a novel approach based on single-molecule TATP detection in the air using a device where tunneling current in N-terminated carbon-nanotubes nanogaps is measured. By employing the density functional theory combined with the non-equilibrium Green's function method, we show that current of tens of nanoamperes passes through TATP trapped in the nanogap, with a discrimination ratio of several orders of magnitude even against prevalent indoor volatile organic compounds (VOCs). This high tunneling current through TATP's highest occupied molecular orbital (HOMO) is facilitated by the strong electric field generated by N-C polar bonds at the electrode ends and by the hybridization between TATP and the electrodes, driven by oxygen atoms within the probed molecule. The application of the same principle is discussed for graphene nanogaps and break-junctions.

Magnetic and spin transport properties of a two-dimensional magnetic semiconductor kagome lattice Nb<sub>3</sub>Cl<sub>8</sub> monolayer

Two-dimensional semiconductor materials with intrinsic magnetism have great application prospects in realizing spintronic devices with low power consumption, small size and high efficiency. Some two-dimensional materials with special lattice structures, such as kagome lattice crystals, are favored by researchers because of their novel properties in magnetism and electronic properties. Recently, a new two-dimensional magnetic semiconductor material Nb<sub>3</sub>Cl<sub>8</sub> monolayer with kagome lattice structure was successfully prepared, which provides a new platform for exploring two-dimensional magnetic semiconductor devices with kagome structure. In this work, we study the electronic structure and magnetic anisotropy of Nb<sub>3</sub>Cl<sub>8</sub> monolayer. We also further construct its <i>p-n</i> junction diode and study its spin transport properties by using density functional theory combined with non-equilibrium Green's function method. The results show that the phonon spectrum of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer has no negative frequency, confirming its dynamic stability. The band gap of the spin-down state (1.157 eV) is significantly larger than that of the spin-up state (0.639 eV). The magnetic moment of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer is 0.997 μ<sub>B</sub>, and its easy magnetization axis is in the plane and along the <i>x</i> axis direction based on its energy of magnetic anisotropy. Nb atoms make the main contribution to the magnetic anisotropy. When the strain is applied, the band gap of the spin-down states will decrease, while the band gap of the spin-up state is monotonously decreased from the negative (compress) to positive (tensile) strain. As the strain variable goes from -6% to 6%, the contribution of Nb atoms to the total magnetic moment gradually increases. Moreover, strain causes the easy magnetization axis of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer to flip vertically from in-plane to out-plane. The designed <i>p-n</i> junction diode nanodevice based on Nb<sub>3</sub>Cl<sub>8</sub> monolayer exhibits an obvious rectification effect. In addition, the current in the spin-up state is larger than that in the spin-down state, exhibiting a spin-polarized transport behavior. Moreover, a negative differential resistance (NDR) phenomenon is also observed, which could be used in the NDR devices. These results demonstrate that the Nb<sub>3</sub>Cl<sub>8</sub> monolayer material has great potential application in the next generation of high-performance spintronic devices, and further experimental verification and exploration of this material and related two-dimensional materials are needed.

Design and analysis of a 2D grapheneplus (G+)-based gas sensor for the detection of multiple organic gases.

A new member of the 2D carbon family, grapheneplus (G+), has demonstrated excellent properties, such as Dirac cones and high surface area. In this study, the electronic transport properties of G+, NG+, and BG+ monolayers in which the NG+/BG+ can be obtained by replacing the center sp3 hybrid carbon atoms of the G+ with N/B atoms, were studied and compared using density functional theory and the non-equilibrium Green's function method. The results revealed that G+ is a semi-metal with two Dirac cones, which becomes metallic upon doping with N or B atoms. Based on the electronic structures, the conductivities of the 2D G+, NG+ and BG+-based nanodevices were analyzed deeply. It was found that the currents of all the designed devices increased with increasing the applied bias voltage, showing obvious quasi-linear current-voltage characteristics. IG+ was significantly higher than ING+ and IBG+ at the same bias voltage, and IG+ was almost twice IBG+, indicating that the electron mobility of G+ can be controlled by B/N doping. Additionally, the gas sensitivities of G+, NG+, and BG+-based gas sensors in detecting C2H4, CH2O, CH4O, and CH4 organic gases were studied. All the considered sensors can chemically adsorb C2H4 and CH2O, but there were only weak van der Waals interactions with CH4O and CH4. For chemical adsorption, the gas sensitivities of these sensors were considerably high and steady, and the sensitivity of NG+ to adsorb C2H4 and CH2O was greater as compared to G+ and BG+ at higher bias voltages. Interestingly, the maximum sensitivity difference for BG+ toward C2H4 and CH2O was 17%, which is better as compared to G+ and NG+. The high sensitivity and different response signals of these sensors were analyzed by transmission spectra and scattering state separation at the Fermi level. Gas sensors based on G+ monolayers can effectively detect organic gases such as C2H4 and CH2O, triggering their broad potential application prospects in the field of gas sensing.

Reconfigurable spin tunnel diodes by doping engineering VS2 monolayers.

We propose a reconfigurable spin tunnel diode based on a small spin-gapped semiconductor (non-doped VS2 monolayer) and semi-metallic magnets (doped VS2 monolayer) separated by a thin insulating tunneling barrier (h-BN). By using first-principles calculations assisted by the nonequilibrium Green's function method, we have carried out a comprehensive study of spin-dependent current and spin transport properties while varying the bias. The device exhibited a magnetization-controlled diode-like behavior with forward-allowed current under antiparallel magnetizations and reverse-forbidden current under parallel magnetizations at the two electrodes. The threshold voltage is tunable by the hole doping density of VS2 monolayers. The doping effect on VS2 monolayers indicates that the magnetic moments, the Heisenberg exchange parameters and Curie temperatures can be monotonically reduced by a larger hole doping density. Our study on VS2 heterostructures has presented a simple and practical device strategy with very promising applications in spintronics.

Large magnetoresistance in phosphorus-sulfur compounds (TMPS4) based temperature regulated spin-caloritronic devices

Two-dimensional (2D) transition metal phosphorus-sulfur compounds (TMPS 4 ) have attracted great theoretical and experimental attention because of their broadband modulation and high hole mobility that can be used in nanodevices. Therefore, their Curie temperature and thermal properties deserve further study for applications in electronic devices. The electromagnetic properties and spin transport properties of 2D transition metal phosphorus-sulfur compounds are systematically investigated by density functional theory (DFT) and DFT combined with the nonequilibrium Green's function method. We find that TMPS 4 materials cover almost all spin electronic behaviors, including half-metals, magnetic and nonmagnetic semiconductors, and metals. The simulation results show that the magnetic tunnel junction constructed based on TMPS 4 has a perfect thermal spin filtering effect and a negative differential resistance effect. Especially, we obtain up to 10 10 % thermal colossal magnetoresistance and almost 100% spin polarization, as well as a high current on/off ratio of ∼10 7 . Based on these results, it is proved that TMPS 4 can be a substrate material for the development of high performance for spin-caloritronic and spintronic devices.

Anisotropic thermoelectric properties in hydrogenated nitrogen-doped porous graphene nanosheets.

By using density functional theory calculations combined with the nonequilibrium Green's function method and machine learning, we systematically studied the thermoelectric properties of four kinds of porous graphene nanosheets (PGNS) before and after nitrogen doping. The results show that the thermoelectric performance of porous graphene nanosheets along the armchair or zigzag chiral direction is improved due to the dramatically enhanced power factor caused by nitrogen doping. The calculated ZT values of nitrogen-doped porous graphene nanosheets are boosted by about one order of magnitude compared with those of undoped porous graphene nanosheets at room temperature. More importantly, an anisotropic thermoelectric transport is found in the nitrogen-doped porous graphene nanosheets. The results show that the ZT values of nitrogen-doped porous graphene nanosheets along the zigzag transport direction are nearly 11 times larger than those of them along the armchair transport direction. These results reveal that the thermoelectric properties of porous graphene nanosheets can be well regulated by nitrogen doping, and provide a good theoretical guidance for their application in thermoelectric devices.

Mechanically controllable conductance in carbon nanotube based nanowires.

Carbon nanotubes (CNTs) are considered to be promising candidates for fabricating nanowires, due to their stable quasi-one-dimensional structure. Controlling the electronic transport properties is one of the most vital issues for molecular nanowires. Herein, using density functional theory combined with nonequilibrium Green's function method, we systematically investigate the current evolution of (4, 4) single-walled CNT based nanowires in squashing processes. When the CNTs are squashed by applying different pressure along the radial direction, a negative correlation can be found between the electrical conductance of the nanowire and the pressure. Besides, the response of the nano junction current to pressure is influenced by the squashing direction. Not only does the geometric structure show symmetry breaking in the specific squashing direction, which causes the CNT electrodes to change from conductors to semiconductors, but also obvious π stacking behavior can be witnessed in this squashing direction. More intriguingly, because the current of the nano junction can be completely cut off by squashing the CNTs, a significant switching behavior with the on/off ratio of up to 103 is obtained at low bias voltages. The underlying mechanisms for these phenomena are revealed by the analysis of the band structures, transmission spectra, frontier molecular orbitals and transmission pathways. These electronic transport properties make CNT a promising candidate for realizing conductance controllable nano devices.

Magnetic and spin transport properties of a two-dimensional magnetic semiconductor kagome lattice Nb<sub>3</sub>Cl<sub>8</sub> monolayer

Two-dimensional semiconductor materials with intrinsic magnetism have great application prospects in realizing spintronic devices with low power consumption, small size and high efficiency. Some two-dimensional materials with special lattice structures, such as kagome lattice crystals, are favored by researchers because of their novel properties in magnetism and electronic properties. Recently, a new two-dimensional magnetic semiconductor material Nb<sub>3</sub>Cl<sub>8</sub> monolayer with kagome lattice structure was successfully prepared, which provides a new platform for exploring two-dimensional magnetic semiconductor devices with kagome structure. In this work, we study the electronic structure and magnetic anisotropy of Nb<sub>3</sub>Cl<sub>8</sub> monolayer. We also further construct its <em>p-n</em> junction diode and study its spin transport properties by using density functional theory combined with non-equilibrium Green's function method. The results show that the phonon spectrum of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer has no negative frequency, confirming its dynamic stability. The band gap of the spin-down state (1.157 eV) is significantly larger than that of the spin-up state (0.639 eV). The magnetic moment of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer is 0.997 μ<sub>B</sub>, and its easy magnetization axis is in the plane and along the <em>x</em> axis direction based on its energy of magnetic anisotropy. Nb atoms make the main contribution to the magnetic anisotropy. When the strain is applied, the band gap of the spin-down states will decrease, while the band gap of the spin-up state is monotonously decreased from the negative (compress) to positive (tensile) strain. As the strain variable goes from -6% to 6%, the contribution of Nb atoms to the total magnetic moment gradually increases. Moreover, strain causes the easy magnetization axis of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer to flip vertically from in-plane to out-plane. The designed <em>p-n</em> junction diode nanodevice based on Nb<sub>3</sub>Cl<sub>8</sub> monolayer exhibits an obvious rectification effect. In addition, the current in the spin-up state is larger than that in the spin-down state, exhibiting a spin-polarized transport behavior. Moreover, a negative differential resistance (NDR) phenomenon is also observed, which could be used in the NDR devices. These results demonstrate that the Nb<sub>3</sub>Cl<sub>8</sub> monolayer material has great potential application in the next generation of high-performance spintronic devices, and further experimental verification and exploration of this material and related two-dimensional materials are needed.

Giant tunneling magnetoresistance in in-plane double-barrier magnetic tunnel junctions based on MXene Cr2C.

The discovery of two-dimensional (2D) magnetic materials makes it possible to realize in-plane magnetic tunnel junctions. In this study, the transport characteristics of an in-plane double barrier magnetic tunnel junction (IDB-MTJ) based on Cr2C have been studied by density functional theory combined with the nonequilibrium Green's function method. The results showed its maximum tunneling magnetoresistance ratio (TMR) value reached 6.58 × 1010. Its minimum TMR value (3.86 × 106) was also comparable to those of conventional field effect transistors (FETs). Due to its giant TMR and unique structural characteristics, the IDB-MTJ based on Cr2C has great potential applications in magnetic random access memory (MRAM) and logic computing.

Spin filtering and negative differential resistance in PAQR-ZGNR junctions

The spin transport of a Polyacene quinone radical (PAQR) molecule sandwiched between two ferromagnetic ZGNR electrodes with an even width number of 6 is studied employing the nonequilibrium Green's function method combined with the density functional theory (NEGF-DFT). Lateral symmetry mismatch of wave functions between PAQR and ZGNR may suppress all the transport channels except only one spin-down channel near the chemical potential in the linear regime. A half-metallic behavior with perfect spin filtering efficiency and strong negative differential resistance is expected. Under high bias voltage, the spin filtering efficiency changes from −100% to 90% when other transport channel is involved. Applying an external gate voltage, we can modulate greatly the conductance of the junction. These unique features are insensitive to the length of PAQR chain and suggest great application prospect for PAQR-ZGNR molecule devices.

Enhanced sensing performance of armchair stanene nanoribbons for lung cancer early detection using an electric field.

In this study, we analyze the effect of a uniform external electric field on the sensing behavior of armchair stanene nanoribbons (ASnNRs) for early detection of lung cancer biomarkers. The Density functional theory (DFT) and non-equilibrium Green function (NEGF) methods are used to study the sensing behavior. We use Ez = 0.4 V Å-1 and Ez = -0.4 V Å-1 as vertical electric fields and Ey = 0.08 V Å-1 and Ey = -0.08 V Å-1 as transverse electric fields. Our findings demonstrate that applying an electric field in a negative/positive direction considerably increases/decreases the magnitude of the adsorption energy and the transferred charge. In the presence of Ez = 0.4 V Å-1 and Ey = -0.08 V Å-1, a substantial decrease in current was observed. Furthermore, the current curves become more distinguishable compared to the absence of electric fields. The computed results indicate that the negative direction of the applied electric field enhanced the sensitivity and selectivity of ASnNRs for the detection of lung cancer-related biomarkers. The computed results also show that using Ez = -0.4 V Å-1 reduces the adsorption energy to Eads = -8.89 eV and enhances the sensitivity up to 41.83% for styrene detection, demonstrating an improvement in the sensing performance compared to the situation without an electric field. These findings have practical implications, as they can be used to develop highly sensitive early-detection gas sensors, potentially saving human lives.

Exploring π-π interactions and electron transport in complexes involving a hexacationic host and PAH guest: a promising avenue for molecular devices.

Single isolated molecules and supramolecular host-guest systems, which consist of π-π stacking interactions, are emerging as promising building blocks for creating molecular electronic devices. In this article, we have investigated the noncovalent π-π interaction and intermolecular electron charge transport involved in a series of host-guest complexes formed between a cage-like host (H6+) and polycyclic aromatic hydrocarbon (PAH) guests (G1-G7) using different quantum chemical approaches. The host (H6+) consists of two triscationic π-electron-deficient trispyridiniumtriazine (TPZ3+) units that are bridged face-to-face by three ethylene-triazole-ethylene. Our theoretical calculations show that the perylene and naphthalene inclusion complexes G7⊂H and G1⊂H have the highest and lowest interaction energies, respectively. In addition, energy decomposition analysis (EDA) indicated that the dispersion interaction term, ΔEdisp, significantly contributes to the host-guest interaction and is correlated with the existence of π-π van der Waals interaction. Using the nonequilibrium Greens function (NEGF) method in combination with density functional theory (DFT), the current-voltage (I-V) curves of the complexes were estimated. The conductance values increased when the guests were embedded inside the host cavity. Notably, the complex G7⊂H has the maximum conductance value. Overall, this study provided the electron transport of the PAH inclusion host-guest complex through π-π interaction and provided a direction for the fabrication of future supramolecular molecular devices.

The Schottky barrier and charge transport through the Cu/Al2O3 interface

The charge transport through the interface between metal and semiconductor is important for conductive performance. In this work, we systematically studied the Schottky barrier and charge transport properties of the Cu/Al2O3 interface. Using density functional theory plus the nonequilibrium green function method, a 8.8 eV bandgap of Al2O3 is obtained and the Schottky barrier is calculated for the oxygen and aluminium terminated interfaces. The charge transport properties are found to depend sensitively on the combination of the interfaces. The Schottky barrier and charge transport properties found in the Cu/Al2O3 interface can guide its applications in the field of integrated circuits and metal-ceramic composites.

Spatiotemporal dynamics of voltage-induced resistance transition in the double-exchange model

We present multi-scale dynamical simulations of voltage-induced insulator-to-metal transition in the double exchange model, a canonical example of itinerant magnet and correlated electron systems. By combining nonequilibrium Green's function method with large-scale Landau-Lifshitz-Gilbert dynamics, we show that the transition from an antiferromagnetic insulator to the low-resistance state is initiated by the nucleation of a thin ferromagnetic conducting layer at the anode. The metal-insulator interface separating the two phases is then driven toward the opposite electrode by the voltage stress, giving rise to a growing metallic region. We further show that the initial transformation kinetics is well described by the Kolmogorov-Avrami-Ishibashi model with an effective spatial-dimension that depends on the applied voltage. Implications of our findings for the resistive switching in colossal magnetoresistant materials are also discussed.

Transport properties of As-F-based molecular magnetic tunnel junctions

By combining the density functional theory with non-equilibrium Green's function method, we theoretically design and investigate the spin-dependent transport properties of two molecular magnetic tunnel junctions (MMTJs) with the AsFNRs embedded in zigzag graphene nanoribbons in parallel and antiparallel spin configurations. The findings reveal that the MMTJs have distinct transport characteristics depending upon the orientations of the AsFNRs. Changing the spin configurations leads to two different net spin currents, and the maximal order of the tunneling magnetoresistance magnitude can reach 107%. In addition, a negative differential resistance (NDR) effect is found in our MMTJs. Our findings provide suitable candidates of MMTJs for the future spintronic devices.

Multifunctional 2D g-C4N3/MoS2 vdW Heterostructure-Based Nanodevices: Spin Filtering and Gas Sensing Properties.

Two-dimensional (2D) magnetic materials are the key to the development of the new generation in spintronics technology and engineering multifunctional devices. Herein, the electronic, spin-resolved transmission, and gas sensing properties of the 2D g-C4N3/MoS2 van der Waals (vdW) heterostructure have been investigated by using density functional theory with non-equilibrium Green's function method. First, the g-C4N3/MoS2 vdW heterostructure demonstrates ferromagnetic half-metallicity and superior adsorption capacity for gas molecules. The spin-dependent electronic transport of the g-C4N3/MoS2-based nanodevice is obviously regulated by parallel or anti-parallel spin configuration in electrodes, leading to perfect single-spin conduction behavior with a nearly 100% spin filtering efficiency, a negative differential resistance effect, and other interesting electrical transport phenomena. Moreover, g-C4N3/MoS2 exhibits directional dependency and strong transport anisotropic behavior under bias windows, indicating that the electric current propagates more easily through the vertical direction than the horizontal direction. The physical mechanisms are revealed and analyzed by presenting the bias-dependent transmission spectra in combination with the projected local device density of states. Finally, the g-C4N3/MoS2-based gas sensor is more sensitive to CO, NO, NO2, and NH3 molecules with the chemisorption type. The strong chemical adsorption leads to the formation of electrons on the local scattering center and ultimately affects the transport properties, resulting in the maximum gas sensitivity reaching 6.45 for NO at the bias of 0.8 V. This work not only reveals that the g-C4N3/MoS2 vdW heterostructure with high anisotropy, perfect spin filtering, and outstanding gas sensitivity is a promising 2D material but also provides an insight into the further application in futuristic electronic nanodevices.