MoS2 Field-effect Transistors Research Articles

Asymmetric Chemical Functionalization of Top-Contact Electrodes: Tuning the Charge Injection for High-Performance MoS2 Field-Effect Transistors and Schottky Diodes.

The fabrication of high-performance (opto-)electronic devices based on 2D channel materials requires the optimization of the charge injection at electrode-semiconductor interfaces. While chemical functionalization with chemisorbed self-assembled monolayers has been extensively exploited to adjust the work function of metallic electrodes in bottom-contact devices, such a strategy has not been demonstrated for the top-contact configuration, despite the latter being known to offer enhanced charge-injection characteristics. Here, a novel contact engineering method is developed to functionalize gold electrodes in top-contact field-effect transistors (FETs) via the transfer of chemically pre-modified electrodes. The source and drain Au electrodes of the molybdenum disulfide (MoS2 ) FETs are functionalized with thiolated molecules possessing different dipole moments. While the modification of the electrodes with electron-donating molecules yields a marked improvement of device performance, the asymmetric functionalization of the source and drain electrodes with different molecules with opposed dipole moment enables the fabrication of a high-performance Schottky diode with a rectification ratio of ≈103 . This unprecedented strategy to tune the charge injection in top-contact MoS2 FETs is of general applicability for the fabrication of high-performance (opto-)electronic devices, in which asymmetric charge injection is required, enabling tailoring of the device characteristics on demand.

Ice-assisted electron-beam lithography for MoS2 transistors with extremely low-energy electrons.

Ice-assisted electron-beam lithography (iEBL) by patterning ice with a focused electron-beam has emerged as a green nanofabrication technique for building nanostructures on diverse substrates. However, materials like atomically thin molybdenum disulfide (MoS2), can be easily damaged by electron irradiation. To ensure the performance of devices based on sensitive materials, it is critical to control electron-beam induced radiolysis in iEBL processes. In this paper, we demonstrate that electron-beam patterning with extremely low-energy electrons followed by a heating process can significantly reduce the damage to substrate materials. A thin film of water ice not only acts as a sacrificial layer for patterning but also becomes a protecting layer for the underlying materials. As a result, MoS2 field effect transistors with back-gate configuration and ohmic contacts have been successfully fabricated. Moreover, the presence or absence of such a protecting layer can lead to the retention or destruction of the underlying MoS2, which provides a flexible method for creating electrical insulation or connection on 2D materials.

Exciton-dominant photoluminescence of MoS2 by a functionalized substrate.

Transition metal dichalcogenides (TMDs) have been considered as promising candidates for transparent and flexible optoelectronic devices owing to their large exciton binding energy and strong light-matter interaction. However, monolayer (1L) TMDs exhibited different intensities and spectra of photoluminescence (PL), and the characteristics of their electronic devices also differed in each study. This has been explained in terms of various defects in TMDs, such as vacancies and grain boundaries, and their surroundings, such as dielectric screening and charged impurities, which lead to non-radiative recombination of trions, low quantum yield (QY), and unexpected doping. However, it should be noted that the surface conditions of the substrate are also a critical factor in determining the properties of TMDs located on the substrate. Here, we demonstrate that the optical and electrical properties of 1L MoS2 are strongly influenced by the functionalized substrate. The PL of 1L MoS2 placed on the oxygen plasma-treated SiO2 substrate was highly p-doped owing to the functional groups of -OH on SiO2, resulting in a strong enhancement of PL by approximately 20 times. The PL QY of 1L MoS2 on plasma-treated SiO2 substrate increased by one order of magnitude. Surprisingly, the observed PL spectra show the suppression of non-radiative recombination by trions, thus the exciton-dominant PL led to a prolonged lifetime of MoS2 on the plasma-treated substrate. The MoS2 field-effect transistors fabricated on plasma-treated SiO2 also exhibited a large hysteresis in the transfer curve owing to charge trapping of the functional groups. Our study demonstrates that the functional groups on the substrate strongly affect the characteristics of 1L MoS2, which provides clues as to why MoS2 exfoliated on various substrates always exhibited different properties in previous studies.

Switching of N- and P-Type Doping with Partial Pressure of Oxygen Gas on Few Layers Mos2-Field Effect Transistor

Switching of N- and P-Type Doping with Partial Pressure of Oxygen Gas on Few Layers Mos2-Field Effect Transistor

Defect-engineered room temperature negative differential resistance in monolayer MoS2 transistors.

The negative differential resistance (NDR) effect has been widely investigated for the development of various electronic devices. Apart from traditional semiconductor-based devices, two-dimensional (2D) transition metal dichalcogenide (TMD)-based field-effect transistors (FETs) have also recently exhibited NDR behavior in several of their heterostructures. However, to observe NDR in the form of monolayer MoS2, theoretical prediction has revealed that the material should be more profoundly affected by sulfur (S) vacancy defects. In this work, monolayer MoS2 FETs with a specific amount of S-vacancy defects are fabricated using three approaches, namely chemical treatment (KOH solution), physical treatment (electron beam bombardment), and as-grown MoS2. Based on systematic studies on the correlation of the S-vacancies with both the device's electron transport characteristics and spectroscopic analysis, the NDR has been clearly observed in the defect-engineered monolayer MoS2 FETs with an S-vacancy (VS) amount of ∼5 ± 0.5%. Consequently, stable NDR behavior can be observed at room temperature, and its peak-to-valley ratio can also be effectively modulated via the gate electric field and light intensity. Through these results, it is envisioned that more electronic applications based on defect-engineered layered TMDs will emerge in the near future.

Thickness and Morphology Dependent Electrical Properties of ALD‐Synthesized MoS2 FETs

AbstractMoS2 is a layered 2D semiconductor with thickness‐dependent electrical properties. Often, 6–12 nm of MoS2 are advised to be used as the channel material in field‐effect transistors (FETs) for achieving an optimal device electrical performance. However, this notion is based on exfoliated MoS2 flakes that cannot be employed for large‐area and wafer‐scale applications. In this work, the thickness‐dependent electrical properties of atomic layer deposition (ALD)‐based MoS2 FETs are studied. A two‐step approach is used for the synthesis of MoS2, wherein large‐area and thickness‐controlled MoOx films are initially grown using plasma‐enhanced (PE‐)ALD and subsequently sulfurized in H2S gas. The number of MoOx PE‐ALD cycles is varied systematically to obtain MoS2 films with a thickness range of 1–10 nm. Current–voltage (I–V) characterization of the fabricated MoS2 FETs with various channel thicknesses reveals that ≈1.2 nm MoS2 suffices in attaining the best device electrical performance. Scanning transmission electron microscopy imaging elucidates that the synthetic MoS2 films are polycrystalline and the resultant ≈1.2 nm of MoS2 are not completely continuous. The empty areas in the polycrystalline MoS2 network can serve as locations for side contact formation, leading to substantial improvements in the device metrics fabricated from such ultrathin MoS2 films.

Sensitive and quantitative detection of SARS-CoV-2 antibodies from vaccinated serum by MoS2-field effect transistor

Recently, the coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally with major impact on public health. Novel methods that enable fast and efficient detection of the virus and the associated biomarkers, such as SARS-CoV-2 antibodies, may provide alterative opportunities for early diagnosis, disease status monitoring, and the development of vaccines. Here, we report the fabrication of a functionalized MoS2-field effect transistor (FET) for sensitive and quantitative detection of antibodies against SARS-CoV-2 spike protein receptor binding domain (S-RBD) in vaccinated serum specimens. The device was modified by SARS-CoV-2 S-RBD fusion protein on the surface and enabled rapid detection of SARS-CoV-2 antibodies. In addition, an on-chip calibration method was established for quantitative measurement. Furthermore, this method was applied to measure the levels of S-RBD antibodies in serum specimens from vaccinated donors. The devices showed no response to negative control samples from individuals who did not receive vaccination, suggesting the high specificity of this method. This study illustrated the successful fabrication of S-RBD functionalized MoS2-FET with potential clinical applications to facilitate vaccine development and efficacy evaluation.

Defects Induced Charge Trapping/Detrapping and Hysteresis Phenomenon in MoS2 Field-Effect Transistors: Mechanism Revealed by Anharmonic Marcus Charge Transfer Theory

One critical problem inhibiting the application of MoS2 field-effect transistors (FETs) is the hysteresis in their transfer characteristics, which is typically associated with charge trapping (CT) and charge detrapping (CDT) induced by atomic defects at the MoS2-dielectric interface. Here, we propose a novel atomistic framework to simulate electronic processes across the MoS2-SiO2 interface, demonstrating the distinct CT/CDT behavior of different types of atomic defects and further revealing the defect type(s) that most likely cause hysteresis. An anharmonic approximation of the classical Marcus theory is developed and combined with state-of-the-art density functional theory to calculate the gate bias-dependent CT/CDT rates. All the key electronic quantities are calculated with Heyd-Scuseria-Ernzerhof hybrid functionals. The results show that single Si-dangling bond defects are active electron trapping centers. Single O-dangling bond defects are active hole trapping centers, which are more likely to be responsible for the hysteresis phenomenon due to their significant CT rate and apparent threshold voltage shift. In contrast, double Si-dangling bond defects are not active trap centers. These findings provide fundamental physical insights for understanding the hysteresis behavior of MoS2 FETs and provide vital support for understanding and solving the reliability of nanoscale devices.

Effect of Al2O3 Passive Layer on Stability and Doping of MoS2 Field-Effect Transistor (FET) Biosensors.

Molybdenum disulfide (MoS2) features a band gap of 1.3 eV (indirect) to 1.9 eV (direct). This tunable band gap renders MoS2 a suitable conducting channel for field-effect transistors (FETs). In addition, the highly sensitive surface potential in MoS2 layers allows the feasibility of FET applications in biosensors, where direct immobilization and detection of biological molecules are conducted in wet conditions. In this work, we report, for the first time, the degradation of chemical vapor deposition (CVD) grown MoS2 FET-based sensors in the presence of phosphate buffer and water, which caused false positive response in detection. We conclude the degradation was originated by physical delamination of MoS2 thin films from the SiO2 substrate. The problem was alleviated by coating the sensors with a 30 nm thick aluminum oxide (Al2O3) layer using atomic layer deposition technique (ALD). This passive oxide thin film not only acted as a protecting layer against the device degradation but also induced a strong n-doping onto MoS2, which permitted a facile method of detection in MoS2 FET-based sensors using a low-power mode chemiresistive I-V measurement at zero gate voltage (Vgate = 0 V). Additionally, the oxide layer provided available sites for facile functionalization with bioreceptors. As immunoreaction plays a key role in clinical diagnosis and environmental analysis, our work presented a promising application using such enhanced Al2O3-coated MoS2 chemiresistive biosensors for detection of HIgG with high sensitivity and selectivity. The biosensor was successfully applied to detect HIgG in artificial urine, a complex matrix containing organics and salts.

2D Indium Phosphorus Sulfide (In2 P3 S9 ): An Emerging van der Waals High-k Dielectrics.

2D van der Waals (vdW) semiconductors hold great potentials for more-than-Moore field-effect transistors (FETs), and the efficient utilization of their theoretical performance requires compatible high-k dielectrics to guarantee the high gate coupling efficiency. The deposition of traditional high-k dielectric oxide films on 2D materials usually generates interface concerns, thereby causing the carrier scattering and degeneration of device performance. Here, utilizing a space-confined epitaxy growth approach, the authors successfully obtained air-stable ultrathin indium phosphorus sulfide (In2 P3 S9 ) nanosheets, the thickness of which can be scaled down to monolayer limit (≈0.69nm) due to its layered structure. 2D In2 P3 S9 exhibits excellent insulating properties, with a high dielectric constant (≈24) and large breakdown voltage (≈8.1MVcm-1 ) at room temperature. Serving as gate insulator, ultrathin In2 P3 S9 nanosheet can be integrated into MoS2 FETs with high-quality dielectric/semiconductor interface, thus providing a competitive electrical performance of device with subthreshold swings (SS) down to 88mVdec-1 and a high ON/OFF ratio of 105 . This study proves an important strategy to prepare 2D vdW high-k dielectrics, and greatly facilitates the ongoing research of 2D materials for functional electronics.

Improved performance of MoS2 FET by in situ NH3 doping in ALD Al2O3 dielectric

Since defects such as traps and oxygen vacancies exist in dielectrics, it is difficult to fabricate a high-performance MoS2 field-effect transistor (FET) using atomic layer deposition (ALD) Al2O3 as the gate dielectric layer. In this paper, NH3 in situ doping, a process treatment approach during ALD growth of Al2O3, is used to decrease these defects for better device characteristics. MoS2 FET has been well fabricated with this technique and the effect of different NH3 in situ doping sequences in the growth cycle has been investigated in detail. Compared with counterparts, those devices with NH3 in situ doping demonstrate obvious performance enhancements: I on/I off is improved by one order of magnitude, from 1.33 × 105 to 3.56 × 106, the threshold voltage shifts from –0.74 V to –0.12 V and a small subthreshold swing of 105 mV/dec is achieved. The improved MoS2 FET performance is attributed to nitrogen doping by the introduction of NH3 during the Al2O3 ALD growth process, which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al2O3 layer. Furthermore, the MoS2 FET processed by in situ NH3 doping after the Al and O precursor filling cycles demonstrates the best performance; this may be because the final NH3 doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS2 channel. The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS2 devices.

Effects of N‐Ion Implantation on the Electrical and Photoelectronic Properties of MoS2 Field Effect Transistors

Ion implantation is widely used in the semiconductor industry as an important method of controlling the performance of semiconductor materials. As a 2D material with fantastic physical characteristics, MoS2 has been receiving extensive attention for its potential applications in electronic devices. N element is an impurity objectively existing in semiconductors. It may come from the semiconductor manufacturing process or the environment. Therefore, the effect of N element implantation on the material, electrical, and photoelectronic properties of MoS2 field effect transistor (FET) is reported. The results of Raman and photoluminescence (PL) shows that N‐ion implant caused the expansion of the MoS2 lattice and the disappearance of the characteristic peaks of PL. The prepared MoS2 FET exhibits a slow photoelectric response to 254 nm UV, and a fast photoelectric response to 650 and 532 nm lasers. After ion implant and annealing, the electrical performance and photocurrent of the MoS2 FET are significantly degraded. The research has a guiding role in impurity control in the semiconductor manufacturing process.

(Invited) Where are the Best Insulators for 2D Field-Effect Transistors?

Two-dimensional (2D) semiconductors are very promising for applications in next-generation field-effect transistors (FETs) which could overcome scaling limitations of Si technologies and thus extend the life of Moore’s law. The success at achieving this ambitious goal will depend on the availability of compatible insulators which are always required to separate the gate from the channel. Ideally, these insulators should go along with 2D semiconductors as well as SiO2 goes with Si. However, the research community is mostly focused on 2D semiconductors while not paying enough attention to finding suitable insulators for 2D FETs. In order to shed some light on this problem, here we formulate general requirements for insulators in 2D FETs and discuss the potential of already used and promising materials.The scaling potential of 2D FETs can be fully exploited only if high quality insulators with an equivalent oxide thickness (EOT) below 1nm are available, as required for low subthreshold swings and reduced power consumption. This results in the following requirements for gate insulators: First, dielectric properties have to be good enough to maintain low tunnel and thermionic leakage currents to achieve high on/off current ratios. This implies high dielectric constants, wide band gaps and large band offsets with the channel material. Second, the insulator must form a well-defined interface with the channel, which is primarily required for a high mobility. Third, the number of active insulator defects within a few nanometers from the interface has to be low, in order to reduce charge trapping and thus maintain high stability of device operation. Finally, the insulators have to be electrically stable when scaled and survive electric fields of at least 10MV/cm.Most previously reported 2D FETs employ conventional oxides (e.g. SiO2, HfO2, Al2O3) known from Si technologies. High-k oxides HfO2 and Al2O3 appear to be the most promising, as they in principle satisfy the requirement on low leakage currents. However, they are amorphous when grown in thin layer, thus forming poor-quality interfaces with 2D channels, and contain numerous unavoidable insulator defects which lead to hysteresis and long-term drifts of the gate transfer characteristics. As a result, it appears to be unlikely that these materials can be considered promising for applications in future fully scalable 2D FETs.In the spirit of Si technologies, a possible alternative to conventional oxides could be oxidation of 2D semiconductors to form native oxides, such as MoO3 from MoS2. However, many of these materials have fundamentally narrow bandgaps of 3-4 eV, while some of them are also non-stoichiometric due to the lack of well-adjusted oxidation methods and thus have a limited dielectric stability. Thus, considerable research efforts are still required to understand their potential.Another possible solution is the use of layered 2D insulators. Their main advantage is their crystalline structure which leads to well-defined interface with 2D semiconductors and a low density of insulator defects. However, the most widely used 2D insulator is hexagonal boron nitride (hBN) which has a narrow bandgap (6eV) and a small dielectric constant (less than 5). This makes it difficult to maintain low gate leakage currents for hBN with sub-1nm EOT. Thus, alternative 2D insulators have to be urgently identified and characterized. Among these materials are mica, which outperforms hBN in terms of dielectric properties, and 2D oxide nanosheets. However, considerable processing advances are required to result in the demonstration of real devices.Finally, another interesting option would be the use of ionic crystals, such as epitaxial fluorides (e.g. CaF2, BaF2, and LaF3). Similar to 2D insulators, fluorides ideally contain a small number of defects and form well-defined interfaces with 2D semiconductors. Also, in contrast to hBN, they have good dielectric properties, e.g. a bandgap of 12.1 eV and a dielectric constant of 8.43 for CaF2. Recently, excellent performance of MoS2 FETs with 2nm thick epitaxial CaF2 (0.9nm EOT) has been achieved, which is currently impossible with any other insulator discussed above. Thus, further research on these insulators appears a very promising way for the development of scalable 2D FETs.In summary, the question about the most promising insulators for 2D FETs is still open. However, already now it is clear that successful integration of amorphous oxides into these devices appears problematic. Thus, it can be concluded that high-quality 2D FETs require crystalline insulators. These can be either layered 2D or ionic crystals with chemically inert surfaces, which generally address the fundamental limitations of oxides. Further research on these materials should target those which have the best dielectric properties and can be synthesized using fully scalable methods.

Effect of CVD parameters on large area growth of highly crystalline MoS2 thin flakes

In this study, we presented a report on effect of growth parameters (seeding promoter, growth temperature, Ar gas flow rate) on the formation of MoS2 monolayer. The morphology and structure of as-grown MoS2 were investigated in detail by optical microscopy, atomic force microscopy, Raman and photoluminesence spectroscopy techniques. The results showed that a highly reproducible growth of dense MoS2 triangular flakes with the size of ~35 µm over large area (~1.5x1 cm2) can be obtained by using a optimized parameters. The MoS2 field effect transistors based on the as-grown MoS2 exhibited carrier mobility of 0.5–2 cm2V−1s−1 and On/Off ratio of ~104. Our results can provide a useful information to realize large area, high quality of MoS2 for real electronic applications.

Demonstration of Stochastic Resonance, Population Coding, and Population Voting Using Artificial MoS2 Based Synapses.

Fast detection of weak signals at low energy expenditure is a challenging but inescapable task for the evolutionary success of animals that survive in resource constrained environments. This task is accomplished by the sensory nervous system by exploiting the synergy between three astounding neural phenomena, namely, stochastic resonance (SR), population coding (PC), and population voting (PV). In SR, the constructive role of synaptic noise is exploited for the detection of otherwise invisible signals. In PC, the redundancy in neural population is exploited to reduce the detection latency. Finally, PV ensures unambiguous signal detection even in the presence of excessive noise. Here we adopt a similar strategies and experimentally demonstrate how a population of stochastic artificial neurons based on monolayer MoS2 field effect transistors (FETs) can use an optimum amount of white Gaussian noise and population voting to detect invisible signals at a frugal energy expenditure (∼10s of nano-Joules). Our findings can aid remote sensing in the emerging era of the Internet of things (IoT) that thrive on energy efficiency.

Wafer-scale functional circuits based on two dimensional semiconductors with fabrication optimized by machine learning

Triggered by the pioneering research on graphene, the family of two-dimensional layered materials (2DLMs) has been investigated for more than a decade, and appealing functionalities have been demonstrated. However, there are still challenges inhibiting high-quality growth and circuit-level integration, and results from previous studies are still far from complying with industrial standards. Here, we overcome these challenges by utilizing machine-learning (ML) algorithms to evaluate key process parameters that impact the electrical characteristics of MoS2 top-gated field-effect transistors (FETs). The wafer-scale fabrication processes are then guided by ML combined with grid searching to co-optimize device performance, including mobility, threshold voltage and subthreshold swing. A 62-level SPICE modeling was implemented for MoS2 FETs and further used to construct functional digital, analog, and photodetection circuits. Finally, we present wafer-scale test FET arrays and a 4-bit full adder employing industry-standard design flows and processes. Taken together, these results experimentally validate the application potential of ML-assisted fabrication optimization for beyond-silicon electronic materials.

Comparison of Ionic Liquid and Ion-Gel Top-Gate MoS2 Field-Effect Transistors

Comparison of Ionic Liquid and Ion-Gel Top-Gate MoS₂ Field-Effect Transistors

Large-Area MoS2 via Colloidal Nanosheet Ink for Integrated Memtransistor.

2D transition metal dichalcogenides (TMDs) exhibit intriguing properties for applications in optoelectronics and electronics, among which memtransistors received extensive attention as multifunctional devices. For practical applications of 2D TMDs, large-area fabrication of the materials via reliable processes, which is in trade-off with their quality, has been a long-standing issue. Here, a simple and effective way is proposed to fabricate large-area and high-quality molybdenum disulfide thin films using MoS2 colloidal ink through a spray coating, followed by a postsulfurization process. High-quality MoS2 thin films exhibit excellent optical and electrical properties that can be utilized in field-effect transistors (FETs) and memtransistor arrays. The MoS2 FETs show an average on/off ratio of 5 × 106 and a high electron mobility of 10.34 cm2 V-1 s-1 , which can be understood by the healing of sulfur vacancies, recrystallization, and the removal of the carbon contamination of the MoS2 . These MoS2 -based memtransistors present stable operations with a high switching ratio tuned by back gate and light illumination, which is promising for multiple-levels memory and complex neuromorphic computing. This study demonstrates a new strategy to fabricate 2D TMDs with large-area and high quality for integrated optoelectronic and memory device applications.

Ambipolar conduction and multicolor photosensing behaviors from poly(9,9-di-n-octylfluorenyl-2,7-diyl)-molybdenum disulfide heterointerfaces

Molybdenum disulfide (MoS2) in two-dimensional (2D) transition metal dichalcogenides (TMDs) has attracted attention as a next-generation semiconductor material owing to its intriguing electrical, optical, and mechanical characteristics, which enable its applications in flexible display backplane thin-film transistors, photodetectors, and complementary metal oxide semiconductor (CMOS) digital circuits. However, MoS2 films only have n-type operating characteristics, and p-type conduction in MoS2 devices has rarely been reported owing to their strong n-type semiconducting property. Herein, we demonstrate the p-doping effects in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO)-MoS2 heterointerface. By simply coating PFO on the top of pre-fabricated MoS2 field effect transistors (FETs), the proposed PFO-MoS2 heterointerface devices could be implemented. A positive shift in the threshold voltage and reduction in the on-current were observed in the proposed PFO-MoS2 heterointerface devices, which indicated ambipolar characteristics with p- and n-type charge transport behaviors. More importantly, the multicolor photosensing behaviors by red, green, and blue light with enhanced sensitivity of PFO-MoS2 hetero-interfacial devices were enhanced.

Highly sensitive detection of multiple proteins from single cells by MoS2-FET biosensors

Single-cell analysis of proteins is critical to gain precise information regarding the mechanisms that dictate the heterogeneity in cellular phenotypes and their differential response to internal and external stimuli. However, tools that allow sensitive and easy measurement of proteins in individual cells are still limited. The emerging semiconductor-based bioelectronics may provide a new approach to overcome the challenges in this field, however its utility in single-cell protein analysis has not been explored. In this study, we investigated multiple protein detection in single cells by MoS2 field effect transistors (MoS2-FETs) modified with specific biological probes. First, β-actin antibody was connected to the surface of MoS2-FETs by covalent bonds, and the fabricated device was tested using β-actin solution with concentrations from 10−9 to 10−3 μg/μL. Next, we examined the application of MoS2-FET for protein analysis in complex biological samples, and the device showed electrical signal response to human embryonic kidney cell line HEK293T in a dose-dependent manner. Furthermore, we applied this method to analyze individual liver cancer MHCC-97L cells, targeting four cellular proteins, including β−actin, epidermal growth factor receptor, sirtuin-2, and glyceraldehyde-3-phosphate dehydrogenase. The devices modified with corresponding probes could identify the target proteins and showed cell number-dependent responses. As a proof of principle, we demonstrated sensitive and multiplexed detection of proteins in single cells using MoS2-FETs. The biosensor and this detection method are cost-efficient and user-friendly with broad application prospects in biological studies and clinical diagnosis.