Molybdenum disulfide (MoS2) has emerged as a typical two-dimensional (2D) material with high carrier mobility, excellent optical response and strong light absorption ability. Theoretically 2D PN homojunction could free from lattice mismatch compared with heterojunction and has greater potential in high photodetection performance. In this study, we first clarified the p-type doping effect caused by nitrogen plasma doping by firstprinciples calculations. Then, nitrogen plasma selective doping was realized by toroidal magnetic field, and PNP bipolar junction transistors (BJT) and photodetectors based on monolayer MoS2 lateral homogeneous PN junctions were fabricated. The current gain alpha of the BJT can reach 0.97, and beta can reach 750. The maximum photoresponsivity of the photodetector reaches 125.9 A/W, the maximum external quantum efficiency reaches 2.93 & times; 104%, and the maximum detectivity reaches 2.57 & times; 1012 Jones. This study shows that the plasma doping process is effective, the BJT exhibits typical current amplification characteristics, and the photodetector has good performance. This doping process is compatible with traditional CMOS processes, and it is an ideal choice for fabricating lateral PN homojunctions for application in next-generation electronic and opto-electronic devices with excellent performance.

Two-dimensional (2D) materials exhibit promising applications in flexible electronics and biosensing due to their unique electrical and mechanical properties. Among them, molybdenum disulfide (MoS2), as a typical 2D semiconductor, demonstrates piezoelectric properties in its monolayer state due to the absence of an inversion symmetry center. This study investigates the piezoelectric behaviors of monolayer MoS2 under strain. Studies of metal-semiconductor (MS) and PN junction devices reveal that MoS2 conductivity is modulated by an internal electric field generated by piezoelectric polarization. This electric field regulates the height of the Schottky barrier at electrode contacts, while compressive strain elevates it and tensile strain lowers it. The results of this study on MS devices fabricated on flexible polyethylene terephthalate (PET) substrates further reveal piezoelectric-dominated asymmetric current modulation. This phenomenon is considered to have the potential to improve the sensing performance for lactic acid detection. Consequently, we conducted lactate sensing under tensile conditions, leading to an approximately five times increase in the sensitivity of flexible MS devices toward lactate (0-1 & micro;M) under 0.29% tensile strain conditions. This study provides a feasible approach for exploring highly sensitive wearable biosensors.

The lactic acid biosensor enhances its detection response to lactic acid concentrations ranging from 0 to 1 µM under 0.29% tensile strain, with sensitivity nearly five times higher than in the unstressed state.

Pulsed laser induced synthesis (PLIS) offers a low-temperature, patternable, and in-situ substitutional doping route for two-dimensional transition metal dichalcogenides (2D TMDs), addressing key challenges in fabrication and doping. Here, we demonstrate the substitutional Hf doping of MoS2 thin films via PLIS to achieve stable p-type conduction. To navigate the complex multi-parameter synthesis space, Bayesian optimization (BO) was employed as an efficient tool to identify optimal growth conditions, enabling high crystalline quality and providing an ideal host lattice for substitutional doping. Field-effect transistors (FETs) fabricated from the BO-optimized Hf-doped MoS2 films exhibit p-type performance with an on/off current ratio > 10(4) and a hole mobility of 20 cm(2) V-1 s(-1), which is approximately three times higher than that of the undoped devices. By investigating the doping mechanism through a combination of Density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS), and FET performance (threshold voltage), our analysis yields a heavily acceptor concentration (7.38 & times; 10(16)cm(-3)) and electrically active acceptor concentration (3.17 & times; 10(16)cm(-3)). This work establishes a closed-loop framework integrating in-situ substitutional doping, mechanism analysis, and data-driven process optimization for the tailored synthesis of functional 2D semiconductors.

In this study, high-performance indium gallium tin oxide (IGTO) and nitrogen (N) doped indium tin oxide (ITO) hetero structured bilayer thin-film transistors (TFTs) are prepared by incorporating an N-doped ITO intercalation layer in single-layer IGTO TFTs. The performance of the IGTO/ITO:N bilayer TFTs is significantly improved compared with single-layer IGTO TFTs, with specific indicators including a field-effect mobility of 332.6 cm(2)/Vs a subthreshold swing of 201 mV/dec, a threshold voltage shifts of 0.21 V and -0.45 V under +/- 10 V gate-bias stress. The results show that the performance enhancement is due to the rational design of the bilayer structure, in which the ITO layer functions as a charge-accumulation layer, providing additional electrons. Meanwhile, N doping effectively reduces the oxygen vacancies, thereby decreasing the interfacial trap density, and ultimately enhancing the performance of single-layer IGTO TFTs. Through X-ray photoelectron spectroscopy and low-frequency noise analyses, we further confirmed the positive effects of N doping and bilayer structure on reducing the defective states and enhancing the stability of TFTs. Overall, the strategy presented here is effective for preparing high performance oxide TFTs for potential applications in future optoelectronic displays.

Two-dimensional (2D) semiconductor components have excellent physical attributes, such as excellent mechanical ductility, high mobility, low dielectric constant, and tunable bandgap, which have attracted much attention to the fields of flexible devices, optoelectronic conversion, and microelectronic devices. Additionally, one-dimensional (1D) semiconductor materials with unique physical attributes, such as high surface area and mechanical potency, show great potential in many applications. However, isolated 1D and 2D materials often do not meet the demand for multifunctionality. Therefore, more functionality is achieved by reconstructing new composite structures from 1D and 2D materials, and according to the current study, it has been demonstrated that hybrid dimensional integration yields a significant enhancement in performance and functionality, which is widely promising in the field of constructing novel electronic and optoelectronic nanodevices. In this review, we first briefly introduce the preparation methods of 1D materials, 2D materials, and 1D/2D heterostructures, as well as their advantages and limitations. The applications of 1D/2D heterostructures in photodetectors, gas sensors, pressure and strain sensors, as well as photoelectrical synapses and biosensors are then discussed, along with the opportunities and challenges of their current applications. Finally, the outlook of the emerging field of 1D/2D heterojunction structures is given.

Herein, highly stable nitrogen (N) doped amorphous indium gallium tin oxide (a-IGTO) thinfilm transistors (TFTs) are prepared and the effects of N-doping are investigated. Compared with undoped a-IGTO TFTs, a-IGTO TFTs with 6 min N plasma treatment exhibit superior bias stress stability and a threshold voltages ( $V_{\mathrm {th}}$ ) closer to 0 V with almost no decline in mobility. In particular, the positive/negative bias stress threshold shift of N-doped a-IGTO TFTs is substantially reduced in both dark and light environment. The X-ray photoelectron spectroscopy analysis (XPS) and low frequency noise (LFN) are employed to study the mechanism of N-doping in a-IGTO TFTs. The XPS results indicate that appropriate amount of N-doping could enhance the bias stress stability and control the $V_{\mathrm {th}}$ efficiently by passivating the defects such as oxygen vacancy in a-IGTO films. The LFN results illustrate that the average interfacial trap density could be reduced by N-doping. Overall, the strategy presented here is effective for preparing a-IGTO TFTs with enhanced stability for potential applications in future optoelectronic displays.

Two-dimensional (2D) materials such as MoS2 have high potential for nanoelectronics because of their nanometer thickness and unique electrical properties. In this study, high-performance nanoscale channel MoS2 vertical field-effect transistors (VFETs) are fabricated using a simplified scaling method compatible with current micro/nanofabrication technologies. The obtained MoS2 VFET with 10 nm channel length (L) delivers a high current up to 537 mu A/mu m and an on-off ratio over 3 x 10(7) at room temperature. Meanwhile, a detailed study of the low-frequency noise (LFN) characteristic is carried out for the fabricated nanoscale MoS2 VFETs. The result shows that all of the MoS2 VFETs fit the classical 1/f noise model in the frequency range from 1 to 10(5) Hz and follows the carrier number fluctuation theory. The LFN of MoS2 VFETs also fits well with the 1/L relationship in the nanoscale channel conditions, which indicates the LFN is mainly generated in the channel region. As LFN performance may strongly depend on the characteristic size of the device, the relationships of normalized noise level with device area and volumetric oxide trap density with 1/L are evaluated. The fabrication strategy presented here provides a way to achieve high-performance 2D nanoscale devices with simplified fabrication processes and also lays the foundation for the study of LFN in nanoelectronics.

Two-dimensional transition metal dichalcogenide (TMDC) thin films have been extensively employed in microelectronics research. Molybdenum disulfide (MoS2), as one of prominent candidates of this class, has been applied in photodetectors, integrated electronic devices, gas sensing, and electrochemical catalysis, owing to its extraordinary optoelectronic, chemical, and mechanical properties. Synthesis of MoS2 crystal film is the key to its application. However, the reported technology revealed several drawbacks, containing limited surface area, prolonged high-temperature environment, and unsatisfying crystallinity. In order to enhance the convenience of MoS2 applications, there is a pressing need for optimized fabrication technology, which could be quicker, with a large area, with adequate crystallinity and heat-saving. In this work, we presented an ultraviolet laser-assisted synthesis technology, accomplishing rapid growth (with the growth rate of about 40 mu m s(-1)) of centimeter-scale MoS2 films at room temperature. To achieve this, we self-assembled a displaceable reaction chamber system, coupled with krypton fluoride ultraviolet pulse laser. The laser motion speed and trajectory could be customized in the software, allowing the maskless patterning of crystal films. As application, we exhibited a photodetector with the integration of synthesized MoS2 and lead sulfide colloidal quantum dots (PbS CQDs), displaying broadband photodetection from ultraviolet, visible to near-infrared spectrum (365-1550 nm), with the detectivity of 10(9)-10(10) Jones, and the rising time of 0.2-0.3 s. This work not only demonstrated a high-process-efficiency synthesis of TMDC materials, but also has opened up new opportunities for ultraviolet laser used in optoelectronics.

Junction field effect transistor (JFET) operates by controlling the thickness of depletion layer in channel with a reverse biased pn junction without dielectric issues, leading to high performance in nanoscale. Two-dimensional MoS2 has shown excellent electronic properties in atomic scale. MoS2 is an n-type semiconductor, therefore JFET based on MoS2 either adopts heterogeneous structure or doping of MoS2 needs to be done. Heterogeneous JFET suffers from lattice mismatching and other interface limitations. Homogeneous JFET with stable doping stands out. Herein, we propose a homogeneous JFET with stable doping by toroidal-magnetic-field controlled nitrogen plasma. The gate-channel pn homojunction in JFET exhibits excellent pn diode rectifying behavior with low reverse current. This JFET shows n-channel characteristics, and by improving contact between electrodes and MoS2, 102 improvement in mobility is demonstrated. The ON/OFF ratio reaches 104 in optimized JFETs.

Molybdenum disulfide (MoS2), a typical two-dimensional layered semiconductor material, is widely studied due its excellent electronic properties in atomic scale. In this study, we achieved the growth of large size few-layer MoS2 films by using molybdenum boat with vertical shield at the end to carry MoO3 precursor in the chemical vapor deposition (CVD) system. The optical microscopy reveals the morphology and lateral size of as-grown films. The Raman spectrum testified that the synthesized films are few-layer MoS2 with defects. Metal-oxide-semiconductor field effect transistors (MOSFETs) based on CVD-grown MoS2 are fabricated, presenting n-type transportation with ION/IOFF ratio about 103. The transportation behaviour of MoS2 MOSFETs is changed from n-type to ambipolar by introducing nitrogen plasma into MoS2 films. The electron or hole transportation in MoS2 is controlled by gate-source voltage. The ambipolar MOSFETs show ION/IOFF ratio about 103.

Two-dimensional transition-metal chalcogenide has become one of the most promising materials for miniaturization beyond Moore's law due to its atomic-level thickness and excellent semiconductor properties. The inverter is the most basic logic gate circuit. Using double-temperature zone chemical vapor deposition and oxygen plasma doping technique, we obtained n-type and p-type MoS2 materials and designed an MoS2 CMOS inverter, showing excellent electrical performance. Under the condition of V-dd = 5 V, the peak voltage gain of the inverter is 7.48, the maximum static power consumption is 37.7 nW, the noise margin low is 0.45V(dd), the noise margin high is 0.32V(dd), and the inverter exhibits better V-in-V-out signal matching. After a 42 day duration in an air environment at room temperature, the V-out of the inverter was reduced by only 3.75% in the case of a high level of output voltage, and the low level of output voltage is basically unchanged.

Monolayer MoS(2)possesses good electron mobility, structural flexibility and a direct band gap, enabling it to be a promising candidate for flexible and wearable optoelectronic devices. In this article, the lateral monolayer MoS(2)homojunctions were prepared by a nitrogen plasma selective doping technique. The monolayer MoS(2)thin films were synthesized by chemical vapor deposition and characterized by photoluminescence, atom force microscope and Raman spectroscopy. The electronic and photoelectric properties of the lateral pn and npn homojunctions were discussed. The results showed that the rectifying ratio of the pn homojunction diode is similar to 10(3). As a photodetector of pn homojunction, the optical responsivity is up to 48.5 A W-1, the external quantum efficiency is 11 301%, the detectivity is similar to 10(9)Jones and the response time is 20 ms with the laser of 532 nm and the reverse bias voltage of 10 V. As a bipolar junction transistor of npn homojunction, the amplification coefficient reached similar to 10(2). A controllable plasma doping technique, compatible with traditional CMOS process, is utilized to realize the monolayer MoS(2)based pn and npn homojunctions, and it propels the potential applications of 2D materials in the electronic, optoelectronic devices and circuits.

This paper describes an innovative method known as pulsed laser induced synthesis to quickly and efficiently produce MoS2 films. Additionally, in situ doping of various elements can be realized via a similar process. This indicates that the proposed method will be a key technology contributing to the industrialization of MoS2 films and other TMDCs.

The sharp interface between thep- andn-type two-dimensional semiconductors is of great importance to realize large-scale production of optoelectronic devices based onp-njunction. In this work, we report a lateral MoS(2)p-nhomojunction implemented by area selective nitrogen plasma doping controlled by toroidal magnetic field. Nitrogen plasma was used to modulate MoS(2)thin films from naturallyn-type top-type, and thus form a lateralp-nhomojunction with the remaining part of the pristinen-type MoS2. Characterization using Raman spectroscopy, photoluminescence and atomic force microscope was carried out to identify thep-type doping effect with low surface damage. The optoelectronic properties based on band structure and carrier transport were discussed. At last, the current-voltage characteristics of the homojunction were investigated and a typical rectifying effect was exhibited. Under AM 1.5 G illumination, solar cells based on the lateralp-nhomojunction displayed photovoltaic properties. The controllable doping technique and the realization ofp-njunction without transfer demonstrate the potential for use in various optoelectronic devices.

Monolayer 2H-phase MoS2-based photodetectors exhibit high photon absorption but suffer from low photoresponse, which severely limits their applications in optoelectronic fields. The metallic IT phase of MoS2, while transporting carriers faster, shows negligible response to visible light, which limits its usage in photodetectors. Herein, we propose an ultrafast-response MoS2 based photodetector having a channel that consists of a 2H-MoS2 sensitizing monolayer on top of 1T@2H-MoS2. The 1T@2HMoS(2) layer has a thickness of several nanometers and is a mixture of metallic 1T-MoS2 and semiconducting 2H-MoS2, imparting metal-like properties to the photodetector. Compared with the monolayer 2H-MoS2 photodetector, we observed a drastic increase in the photoresponse of the 2H-MoS2/1T@2H-MoS2 vertically stacked photodetector to a value of 1917 A W-1. Owing to the presence of metallic 1T-MoS2 within the metal-like 1T@2H-MoS2, the performance of the 2H-MoS2/1T@2H-MoS2 vertically stacked photodetector is voltage bias-modulated with an external quantum efficiency (EQE) of up to 448,384% and a specific detectivity of up to similar to 10(11) Jones. The higher carrier density and higher mobility of the 1T@2H-MoS2 layer explain the better bias-modulated performance. In addition, the interface between 2H-MoS2 and 1T@2H-MoS2 ensures fewer dangling bonds and reduced lattice mismatching. Thus, this study presents an exclusive vertically stacked MoS2-based photodetector that lays the foundation for the development of photodetectors exhibiting higher photoresponse.

Molybdenum disulfide (MoS2) is a cutting-edge layer-dependent two dimensional semiconductor which monolayer is direct-bandgap. Nano-scale monolayer MoS2 has big potential in electronics and optoelectronics devices. In this work we reported the progress in growing continuous single layer MoS2 by ambient pressure chemical vapor deposition (APCVD). Scanning electron microscope (SEM), Raman, photoluminescence spectra (PL) and atomic force microscopy (AFM) disclose that as-grown films are large-area monolayer and of high quality. SEM observations also clearly reveal the growth process of these films. Figuring out the growth mechanism grants growth of large scale continuous MoS2, and lays the foundation for wide device applications in the future.

Low damaged doping of two-dimensional (2D) materials proves to be a significant obstacle in realizing fundamental devices such as p-n junction diodes and transistors due to its atom layer thickness. In this work, the defect formation energy and p-type conduction behavior of nitrogen plasma doping are investigated by first principle calculation. Low damaged substitutional p-type doping in MoS2 using low energy nitrogen plasma composed of N+ and N-2(+) is achieved by a novel toroidal magnetic field (TMF). The TMF helps to raise the concentration of N-2(+) ions at low RF power condition. The electrical characteristics of double-layer MoS2 field-effect transistors (FETs) clearly show an efficient p-type doping behavior. Atomic force microscope is applied to verify the slight damage in MoS2. X-ray photoelectron spectroscopy, photoluminescence and Raman spectroscopy confirm the effective p-type doping characteristic with weak damage. These findings provide a low damage technology for efficient carrier modulation of MoS2 and other homogeneous TMDC materials, which overcomes barriers in developing 2D electronic and optoelectronic devices.

P-type transition metal dichalcogenides (TMDCs) field-effect transistor (FET) with high performance is fundamental for the development of 2D electronic and optoelectronic devices. We achieve the effective p-type doping using toroidal-magnetic-field (TMF) controlled oxygen plasma on the six-layer MoS2. The bottom-gated MoS2 FET shows a record current on-off ratio of 107, a hole mobility of 115.2 cm(2) V-1 s(-1) and a subthreshold swing of 137 mV dec(-1) at room temperature. The high performance is attributed to the negligible lattice defects and high substitutional rate through restricting the energy of oxygen ions, which are demonstrated by Raman spectroscopy, photoluminescence spectroscopy and x-ray photoelectron spectroscopy. The excellent p-type conduction is also beneficial from enhancing the ratio of O-2(+) ions in oxygen plasma by the TMF. First-principle calculations validate that O-2(+) ions lead to a shallow acceptor level at 42.16 meV above the valance band maximum and extracting 1.0 electron from MoS2 lattice. These findings provide a scheme for realizing 2D integrated circuit and excellent optoelectronic devices using MoS2 and other homogeneous TMDCs.